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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package jsr166y; |
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import java.util.concurrent.*; |
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import java.util.ArrayList; |
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import java.util.Arrays; |
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import java.util.Collection; |
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import java.util.Collections; |
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import java.util.List; |
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import java.util.concurrent.locks.Condition; |
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import java.util.Random; |
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import java.util.concurrent.AbstractExecutorService; |
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import java.util.concurrent.Callable; |
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import java.util.concurrent.ExecutorService; |
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import java.util.concurrent.Future; |
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import java.util.concurrent.RejectedExecutionException; |
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import java.util.concurrent.RunnableFuture; |
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import java.util.concurrent.TimeUnit; |
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import java.util.concurrent.atomic.AtomicInteger; |
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import java.util.concurrent.locks.LockSupport; |
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import java.util.concurrent.locks.ReentrantLock; |
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import java.util.concurrent.atomic.AtomicInteger; |
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import java.util.concurrent.atomic.AtomicLong; |
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import java.util.concurrent.locks.Condition; |
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|
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/** |
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* An {@link ExecutorService} for running {@link ForkJoinTask}s. A |
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* ForkJoinPool provides the entry point for submissions from |
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* non-ForkJoinTasks, as well as management and monitoring operations. |
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* Normally a single ForkJoinPool is used for a large number of |
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* submitted tasks. Otherwise, use would not usually outweigh the |
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* construction and bookkeeping overhead of creating a large set of |
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* threads. |
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* An {@link ExecutorService} for running {@link ForkJoinTask}s. |
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* A {@code ForkJoinPool} provides the entry point for submissions |
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* from non-{@code ForkJoinTask} clients, as well as management and |
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* monitoring operations. |
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* |
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* <p>ForkJoinPools differ from other kinds of Executors mainly in |
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* that they provide <em>work-stealing</em>: all threads in the pool |
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* attempt to find and execute subtasks created by other active tasks |
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* (eventually blocking if none exist). This makes them efficient when |
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* most tasks spawn other subtasks (as do most ForkJoinTasks), as well |
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* as the mixed execution of some plain Runnable- or Callable- based |
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* activities along with ForkJoinTasks. When setting |
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* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for |
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* use with fine-grained tasks that are never joined. Otherwise, other |
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* ExecutorService implementations are typically more appropriate |
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* choices. |
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* <p>A {@code ForkJoinPool} differs from other kinds of {@link |
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* ExecutorService} mainly by virtue of employing |
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* <em>work-stealing</em>: all threads in the pool attempt to find and |
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* execute subtasks created by other active tasks (eventually blocking |
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* waiting for work if none exist). This enables efficient processing |
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* when most tasks spawn other subtasks (as do most {@code |
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* ForkJoinTask}s). When setting <em>asyncMode</em> to true in |
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* constructors, {@code ForkJoinPool}s may also be appropriate for use |
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* with event-style tasks that are never joined. |
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* |
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* <p>A ForkJoinPool may be constructed with a given parallelism level |
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* (target pool size), which it attempts to maintain by dynamically |
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* adding, suspending, or resuming threads, even if some tasks are |
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* waiting to join others. However, no such adjustments are performed |
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* in the face of blocked IO or other unmanaged synchronization. The |
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* nested {@code ManagedBlocker} interface enables extension of |
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* the kinds of synchronization accommodated. The target parallelism |
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* level may also be changed dynamically ({@code setParallelism}) |
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* and thread construction can be limited using methods |
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* {@code setMaximumPoolSize} and/or |
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* {@code setMaintainsParallelism}. |
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* <p>A {@code ForkJoinPool} is constructed with a given target |
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* parallelism level; by default, equal to the number of available |
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* processors. The pool attempts to maintain enough active (or |
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* available) threads by dynamically adding, suspending, or resuming |
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* internal worker threads, even if some tasks are stalled waiting to |
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* join others. However, no such adjustments are guaranteed in the |
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* face of blocked IO or other unmanaged synchronization. The nested |
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* {@link ManagedBlocker} interface enables extension of the kinds of |
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* synchronization accommodated. |
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* |
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* <p>In addition to execution and lifecycle control methods, this |
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* class provides status check methods (for example |
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* {@code getStealCount}) that are intended to aid in developing, |
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* {@link #getStealCount}) that are intended to aid in developing, |
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* tuning, and monitoring fork/join applications. Also, method |
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* {@code toString} returns indications of pool state in a |
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* {@link #toString} returns indications of pool state in a |
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* convenient form for informal monitoring. |
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* |
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* <p> As is the case with other ExecutorServices, there are three |
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* main task execution methods summarized in the following |
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* table. These are designed to be used by clients not already engaged |
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* in fork/join computations in the current pool. The main forms of |
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* these methods accept instances of {@code ForkJoinTask}, but |
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* overloaded forms also allow mixed execution of plain {@code |
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* Runnable}- or {@code Callable}- based activities as well. However, |
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* tasks that are already executing in a pool should normally |
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* <em>NOT</em> use these pool execution methods, but instead use the |
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* within-computation forms listed in the table. |
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* |
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* <table BORDER CELLPADDING=3 CELLSPACING=1> |
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* <tr> |
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* <td></td> |
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* <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td> |
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* <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td> |
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* </tr> |
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* <tr> |
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* <td> <b>Arrange async execution</td> |
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* <td> {@link #execute(ForkJoinTask)}</td> |
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* <td> {@link ForkJoinTask#fork}</td> |
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* </tr> |
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* <tr> |
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* <td> <b>Await and obtain result</td> |
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* <td> {@link #invoke(ForkJoinTask)}</td> |
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* <td> {@link ForkJoinTask#invoke}</td> |
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* </tr> |
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* <tr> |
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* <td> <b>Arrange exec and obtain Future</td> |
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* <td> {@link #submit(ForkJoinTask)}</td> |
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* <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td> |
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* </tr> |
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* </table> |
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* |
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* <p><b>Sample Usage.</b> Normally a single {@code ForkJoinPool} is |
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* used for all parallel task execution in a program or subsystem. |
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* Otherwise, use would not usually outweigh the construction and |
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* bookkeeping overhead of creating a large set of threads. For |
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* example, a common pool could be used for the {@code SortTasks} |
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* illustrated in {@link RecursiveAction}. Because {@code |
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* ForkJoinPool} uses threads in {@linkplain java.lang.Thread#isDaemon |
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* daemon} mode, there is typically no need to explicitly {@link |
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* #shutdown} such a pool upon program exit. |
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* |
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* <pre> {@code |
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* static final ForkJoinPool mainPool = new ForkJoinPool(); |
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* ... |
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* public void sort(long[] array) { |
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* mainPool.invoke(new SortTask(array, 0, array.length)); |
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* }}</pre> |
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* |
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* <p><b>Implementation notes</b>: This implementation restricts the |
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* maximum number of running threads to 32767. Attempts to create |
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* pools with greater than the maximum result in |
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* IllegalArgumentExceptions. |
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* pools with greater than the maximum number result in |
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* {@code IllegalArgumentException}. |
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* |
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* <p>This implementation rejects submitted tasks (that is, by throwing |
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* {@link RejectedExecutionException}) only when the pool is shut down |
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* or internal resources have been exhausted. |
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* |
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* @since 1.7 |
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* @author Doug Lea |
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public class ForkJoinPool extends AbstractExecutorService { |
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/* |
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* See the extended comments interspersed below for design, |
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* rationale, and walkthroughs. |
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*/ |
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|
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/** Mask for packing and unpacking shorts */ |
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private static final int shortMask = 0xffff; |
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|
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/** Max pool size -- must be a power of two minus 1 */ |
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private static final int MAX_THREADS = 0x7FFF; |
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|
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/** |
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* Factory for creating new ForkJoinWorkerThreads. A |
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* ForkJoinWorkerThreadFactory must be defined and used for |
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* ForkJoinWorkerThread subclasses that extend base functionality |
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* or initialize threads with different contexts. |
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* Implementation Overview |
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* |
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* This class provides the central bookkeeping and control for a |
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* set of worker threads: Submissions from non-FJ threads enter |
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* into a submission queue. Workers take these tasks and typically |
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* split them into subtasks that may be stolen by other workers. |
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* Preference rules give first priority to processing tasks from |
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* their own queues (LIFO or FIFO, depending on mode), then to |
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* randomized FIFO steals of tasks in other worker queues, and |
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* lastly to new submissions. |
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* |
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* The main throughput advantages of work-stealing stem from |
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* decentralized control -- workers mostly take tasks from |
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* themselves or each other. We cannot negate this in the |
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* implementation of other management responsibilities. The main |
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* tactic for avoiding bottlenecks is packing nearly all |
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* essentially atomic control state into a single 64bit volatile |
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* variable ("ctl"). This variable is read on the order of 10-100 |
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* times as often as it is modified (always via CAS). (There is |
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* some additional control state, for example variable "shutdown" |
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* for which we can cope with uncoordinated updates.) This |
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* streamlines synchronization and control at the expense of messy |
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* constructions needed to repack status bits upon updates. |
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* Updates tend not to contend with each other except during |
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* bursts while submitted tasks begin or end. In some cases when |
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* they do contend, threads can instead do something else |
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* (usually, scan for tasks) until contention subsides. |
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* |
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* To enable packing, we restrict maximum parallelism to (1<<15)-1 |
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* (which is far in excess of normal operating range) to allow |
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* ids, counts, and their negations (used for thresholding) to fit |
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* into 16bit fields. |
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* |
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* Recording Workers. Workers are recorded in the "workers" array |
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* that is created upon pool construction and expanded if (rarely) |
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* necessary. This is an array as opposed to some other data |
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* structure to support index-based random steals by workers. |
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* Updates to the array recording new workers and unrecording |
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* terminated ones are protected from each other by a seqLock |
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* (scanGuard) but the array is otherwise concurrently readable, |
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* and accessed directly by workers. To simplify index-based |
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* operations, the array size is always a power of two, and all |
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* readers must tolerate null slots. To avoid flailing during |
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* start-up, the array is presized to hold twice #parallelism |
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* workers (which is unlikely to need further resizing during |
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* execution). But to avoid dealing with so many null slots, |
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* variable scanGuard includes a mask for the nearest power of two |
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* that contains all current workers. All worker thread creation |
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* is on-demand, triggered by task submissions, replacement of |
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* terminated workers, and/or compensation for blocked |
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* workers. However, all other support code is set up to work with |
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* other policies. To ensure that we do not hold on to worker |
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* references that would prevent GC, ALL accesses to workers are |
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* via indices into the workers array (which is one source of some |
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* of the messy code constructions here). In essence, the workers |
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* array serves as a weak reference mechanism. Thus for example |
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* the wait queue field of ctl stores worker indices, not worker |
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* references. Access to the workers in associated methods (for |
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* example signalWork) must both index-check and null-check the |
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* IDs. All such accesses ignore bad IDs by returning out early |
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* from what they are doing, since this can only be associated |
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* with termination, in which case it is OK to give up. |
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* |
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* All uses of the workers array, as well as queue arrays, check |
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* that the array is non-null (even if previously non-null). This |
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* allows nulling during termination, which is currently not |
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* necessary, but remains an option for resource-revocation-based |
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* shutdown schemes. |
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* |
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* Wait Queuing. Unlike HPC work-stealing frameworks, we cannot |
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* let workers spin indefinitely scanning for tasks when none can |
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* be found immediately, and we cannot start/resume workers unless |
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* there appear to be tasks available. On the other hand, we must |
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* quickly prod them into action when new tasks are submitted or |
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* generated. We park/unpark workers after placing in an event |
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* wait queue when they cannot find work. This "queue" is actually |
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* a simple Treiber stack, headed by the "id" field of ctl, plus a |
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* 15bit counter value to both wake up waiters (by advancing their |
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* count) and avoid ABA effects. Successors are held in worker |
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* field "nextWait". Queuing deals with several intrinsic races, |
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* mainly that a task-producing thread can miss seeing (and |
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* signalling) another thread that gave up looking for work but |
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* has not yet entered the wait queue. We solve this by requiring |
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* a full sweep of all workers both before (in scan()) and after |
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* (in tryAwaitWork()) a newly waiting worker is added to the wait |
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* queue. During a rescan, the worker might release some other |
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* queued worker rather than itself, which has the same net |
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* effect. Because enqueued workers may actually be rescanning |
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* rather than waiting, we set and clear the "parked" field of |
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* ForkJoinWorkerThread to reduce unnecessary calls to unpark. |
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* (Use of the parked field requires a secondary recheck to avoid |
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* missed signals.) |
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* |
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* Signalling. We create or wake up workers only when there |
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* appears to be at least one task they might be able to find and |
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* execute. When a submission is added or another worker adds a |
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* task to a queue that previously had two or fewer tasks, they |
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* signal waiting workers (or trigger creation of new ones if |
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* fewer than the given parallelism level -- see signalWork). |
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* These primary signals are buttressed by signals during rescans |
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* as well as those performed when a worker steals a task and |
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* notices that there are more tasks too; together these cover the |
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* signals needed in cases when more than two tasks are pushed |
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* but untaken. |
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* |
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* Trimming workers. To release resources after periods of lack of |
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* use, a worker starting to wait when the pool is quiescent will |
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* time out and terminate if the pool has remained quiescent for |
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* SHRINK_RATE nanosecs. This will slowly propagate, eventually |
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* terminating all workers after long periods of non-use. |
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* |
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* Submissions. External submissions are maintained in an |
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* array-based queue that is structured identically to |
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* ForkJoinWorkerThread queues except for the use of |
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* submissionLock in method addSubmission. Unlike the case for |
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* worker queues, multiple external threads can add new |
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* submissions, so adding requires a lock. |
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* |
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* Compensation. Beyond work-stealing support and lifecycle |
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* control, the main responsibility of this framework is to take |
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* actions when one worker is waiting to join a task stolen (or |
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* always held by) another. Because we are multiplexing many |
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* tasks on to a pool of workers, we can't just let them block (as |
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* in Thread.join). We also cannot just reassign the joiner's |
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* run-time stack with another and replace it later, which would |
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* be a form of "continuation", that even if possible is not |
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* necessarily a good idea since we sometimes need both an |
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* unblocked task and its continuation to progress. Instead we |
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* combine two tactics: |
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* |
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* Helping: Arranging for the joiner to execute some task that it |
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* would be running if the steal had not occurred. Method |
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* ForkJoinWorkerThread.joinTask tracks joining->stealing |
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* links to try to find such a task. |
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* |
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* Compensating: Unless there are already enough live threads, |
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* method tryPreBlock() may create or re-activate a spare |
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* thread to compensate for blocked joiners until they |
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* unblock. |
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* |
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* The ManagedBlocker extension API can't use helping so relies |
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* only on compensation in method awaitBlocker. |
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* |
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* It is impossible to keep exactly the target parallelism number |
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* of threads running at any given time. Determining the |
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* existence of conservatively safe helping targets, the |
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* availability of already-created spares, and the apparent need |
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* to create new spares are all racy and require heuristic |
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* guidance, so we rely on multiple retries of each. Currently, |
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* in keeping with on-demand signalling policy, we compensate only |
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* if blocking would leave less than one active (non-waiting, |
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* non-blocked) worker. Additionally, to avoid some false alarms |
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* due to GC, lagging counters, system activity, etc, compensated |
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* blocking for joins is only attempted after rechecks stabilize |
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* (retries are interspersed with Thread.yield, for good |
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* citizenship). The variable blockedCount, incremented before |
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* blocking and decremented after, is sometimes needed to |
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* distinguish cases of waiting for work vs blocking on joins or |
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* other managed sync. Both cases are equivalent for most pool |
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* control, so we can update non-atomically. (Additionally, |
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* contention on blockedCount alleviates some contention on ctl). |
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* |
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* Shutdown and Termination. A call to shutdownNow atomically sets |
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* the ctl stop bit and then (non-atomically) sets each workers |
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* "terminate" status, cancels all unprocessed tasks, and wakes up |
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* all waiting workers. Detecting whether termination should |
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* commence after a non-abrupt shutdown() call requires more work |
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* and bookkeeping. We need consensus about quiescence (i.e., that |
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* there is no more work) which is reflected in active counts so |
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* long as there are no current blockers, as well as possible |
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* re-evaluations during independent changes in blocking or |
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* quiescing workers. |
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* |
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* Style notes: There is a lot of representation-level coupling |
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* among classes ForkJoinPool, ForkJoinWorkerThread, and |
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* ForkJoinTask. Most fields of ForkJoinWorkerThread maintain |
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* data structures managed by ForkJoinPool, so are directly |
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* accessed. Conversely we allow access to "workers" array by |
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* workers, and direct access to ForkJoinTask.status by both |
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* ForkJoinPool and ForkJoinWorkerThread. There is little point |
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* trying to reduce this, since any associated future changes in |
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* representations will need to be accompanied by algorithmic |
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* changes anyway. All together, these low-level implementation |
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* choices produce as much as a factor of 4 performance |
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* improvement compared to naive implementations, and enable the |
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* processing of billions of tasks per second, at the expense of |
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* some ugliness. |
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* |
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* Methods signalWork() and scan() are the main bottlenecks so are |
315 |
> |
* especially heavily micro-optimized/mangled. There are lots of |
316 |
> |
* inline assignments (of form "while ((local = field) != 0)") |
317 |
> |
* which are usually the simplest way to ensure the required read |
318 |
> |
* orderings (which are sometimes critical). This leads to a |
319 |
> |
* "C"-like style of listing declarations of these locals at the |
320 |
> |
* heads of methods or blocks. There are several occurrences of |
321 |
> |
* the unusual "do {} while (!cas...)" which is the simplest way |
322 |
> |
* to force an update of a CAS'ed variable. There are also other |
323 |
> |
* coding oddities that help some methods perform reasonably even |
324 |
> |
* when interpreted (not compiled). |
325 |
> |
* |
326 |
> |
* The order of declarations in this file is: (1) declarations of |
327 |
> |
* statics (2) fields (along with constants used when unpacking |
328 |
> |
* some of them), listed in an order that tends to reduce |
329 |
> |
* contention among them a bit under most JVMs. (3) internal |
330 |
> |
* control methods (4) callbacks and other support for |
331 |
> |
* ForkJoinTask and ForkJoinWorkerThread classes, (5) exported |
332 |
> |
* methods (plus a few little helpers). (6) static block |
333 |
> |
* initializing all statics in a minimally dependent order. |
334 |
> |
*/ |
335 |
> |
|
336 |
> |
/** |
337 |
> |
* Factory for creating new {@link ForkJoinWorkerThread}s. |
338 |
> |
* A {@code ForkJoinWorkerThreadFactory} must be defined and used |
339 |
> |
* for {@code ForkJoinWorkerThread} subclasses that extend base |
340 |
> |
* functionality or initialize threads with different contexts. |
341 |
|
*/ |
342 |
|
public static interface ForkJoinWorkerThreadFactory { |
343 |
|
/** |
344 |
|
* Returns a new worker thread operating in the given pool. |
345 |
|
* |
346 |
|
* @param pool the pool this thread works in |
347 |
< |
* @throws NullPointerException if pool is null |
347 |
> |
* @throws NullPointerException if the pool is null |
348 |
|
*/ |
349 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool); |
350 |
|
} |
353 |
|
* Default ForkJoinWorkerThreadFactory implementation; creates a |
354 |
|
* new ForkJoinWorkerThread. |
355 |
|
*/ |
356 |
< |
static class DefaultForkJoinWorkerThreadFactory |
356 |
> |
static class DefaultForkJoinWorkerThreadFactory |
357 |
|
implements ForkJoinWorkerThreadFactory { |
358 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool) { |
359 |
< |
try { |
107 |
< |
return new ForkJoinWorkerThread(pool); |
108 |
< |
} catch (OutOfMemoryError oom) { |
109 |
< |
return null; |
110 |
< |
} |
359 |
> |
return new ForkJoinWorkerThread(pool); |
360 |
|
} |
361 |
|
} |
362 |
|
|
365 |
|
* overridden in ForkJoinPool constructors. |
366 |
|
*/ |
367 |
|
public static final ForkJoinWorkerThreadFactory |
368 |
< |
defaultForkJoinWorkerThreadFactory = |
120 |
< |
new DefaultForkJoinWorkerThreadFactory(); |
368 |
> |
defaultForkJoinWorkerThreadFactory; |
369 |
|
|
370 |
|
/** |
371 |
|
* Permission required for callers of methods that may start or |
372 |
|
* kill threads. |
373 |
|
*/ |
374 |
< |
private static final RuntimePermission modifyThreadPermission = |
127 |
< |
new RuntimePermission("modifyThread"); |
374 |
> |
private static final RuntimePermission modifyThreadPermission; |
375 |
|
|
376 |
|
/** |
377 |
|
* If there is a security manager, makes sure caller has |
386 |
|
/** |
387 |
|
* Generator for assigning sequence numbers as pool names. |
388 |
|
*/ |
389 |
< |
private static final AtomicInteger poolNumberGenerator = |
143 |
< |
new AtomicInteger(); |
389 |
> |
private static final AtomicInteger poolNumberGenerator; |
390 |
|
|
391 |
|
/** |
392 |
< |
* Array holding all worker threads in the pool. Initialized upon |
393 |
< |
* first use. Array size must be a power of two. Updates and |
394 |
< |
* replacements are protected by workerLock, but it is always kept |
395 |
< |
* in a consistent enough state to be randomly accessed without |
396 |
< |
* locking by workers performing work-stealing. |
392 |
> |
* Generator for initial random seeds for worker victim |
393 |
> |
* selection. This is used only to create initial seeds. Random |
394 |
> |
* steals use a cheaper xorshift generator per steal attempt. We |
395 |
> |
* don't expect much contention on seedGenerator, so just use a |
396 |
> |
* plain Random. |
397 |
|
*/ |
398 |
< |
volatile ForkJoinWorkerThread[] workers; |
398 |
> |
static final Random workerSeedGenerator; |
399 |
|
|
400 |
|
/** |
401 |
< |
* Lock protecting access to workers. |
401 |
> |
* Array holding all worker threads in the pool. Initialized upon |
402 |
> |
* construction. Array size must be a power of two. Updates and |
403 |
> |
* replacements are protected by scanGuard, but the array is |
404 |
> |
* always kept in a consistent enough state to be randomly |
405 |
> |
* accessed without locking by workers performing work-stealing, |
406 |
> |
* as well as other traversal-based methods in this class, so long |
407 |
> |
* as reads memory-acquire by first reading ctl. All readers must |
408 |
> |
* tolerate that some array slots may be null. |
409 |
|
*/ |
410 |
< |
private final ReentrantLock workerLock; |
410 |
> |
ForkJoinWorkerThread[] workers; |
411 |
|
|
412 |
|
/** |
413 |
< |
* Condition for awaitTermination. |
413 |
> |
* Initial size for submission queue array. Must be a power of |
414 |
> |
* two. In many applications, these always stay small so we use a |
415 |
> |
* small initial cap. |
416 |
|
*/ |
417 |
< |
private final Condition termination; |
417 |
> |
private static final int INITIAL_QUEUE_CAPACITY = 8; |
418 |
> |
|
419 |
> |
/** |
420 |
> |
* Maximum size for submission queue array. Must be a power of two |
421 |
> |
* less than or equal to 1 << (31 - width of array entry) to |
422 |
> |
* ensure lack of index wraparound, but is capped at a lower |
423 |
> |
* value to help users trap runaway computations. |
424 |
> |
*/ |
425 |
> |
private static final int MAXIMUM_QUEUE_CAPACITY = 1 << 24; // 16M |
426 |
|
|
427 |
|
/** |
428 |
< |
* The uncaught exception handler used when any worker |
166 |
< |
* abruptly terminates |
428 |
> |
* Array serving as submission queue. Initialized upon construction. |
429 |
|
*/ |
430 |
< |
private Thread.UncaughtExceptionHandler ueh; |
430 |
> |
private ForkJoinTask<?>[] submissionQueue; |
431 |
> |
|
432 |
> |
/** |
433 |
> |
* Lock protecting submissions array for addSubmission |
434 |
> |
*/ |
435 |
> |
private final ReentrantLock submissionLock; |
436 |
> |
|
437 |
> |
/** |
438 |
> |
* Condition for awaitTermination, using submissionLock for |
439 |
> |
* convenience. |
440 |
> |
*/ |
441 |
> |
private final Condition termination; |
442 |
|
|
443 |
|
/** |
444 |
|
* Creation factory for worker threads. |
446 |
|
private final ForkJoinWorkerThreadFactory factory; |
447 |
|
|
448 |
|
/** |
449 |
< |
* Head of stack of threads that were created to maintain |
450 |
< |
* parallelism when other threads blocked, but have since |
178 |
< |
* suspended when the parallelism level rose. |
449 |
> |
* The uncaught exception handler used when any worker abruptly |
450 |
> |
* terminates. |
451 |
|
*/ |
452 |
< |
private volatile WaitQueueNode spareStack; |
452 |
> |
final Thread.UncaughtExceptionHandler ueh; |
453 |
|
|
454 |
|
/** |
455 |
< |
* Sum of per-thread steal counts, updated only when threads are |
184 |
< |
* idle or terminating. |
455 |
> |
* Prefix for assigning names to worker threads |
456 |
|
*/ |
457 |
< |
private final AtomicLong stealCount; |
457 |
> |
private final String workerNamePrefix; |
458 |
|
|
459 |
|
/** |
460 |
< |
* Queue for external submissions. |
460 |
> |
* Sum of per-thread steal counts, updated only when threads are |
461 |
> |
* idle or terminating. |
462 |
|
*/ |
463 |
< |
private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue; |
463 |
> |
private volatile long stealCount; |
464 |
|
|
465 |
|
/** |
466 |
< |
* Head of Treiber stack for barrier sync. See below for explanation. |
466 |
> |
* Main pool control -- a long packed with: |
467 |
> |
* AC: Number of active running workers minus target parallelism (16 bits) |
468 |
> |
* TC: Number of total workers minus target parallelism (16bits) |
469 |
> |
* ST: true if pool is terminating (1 bit) |
470 |
> |
* EC: the wait count of top waiting thread (15 bits) |
471 |
> |
* ID: ~poolIndex of top of Treiber stack of waiting threads (16 bits) |
472 |
> |
* |
473 |
> |
* When convenient, we can extract the upper 32 bits of counts and |
474 |
> |
* the lower 32 bits of queue state, u = (int)(ctl >>> 32) and e = |
475 |
> |
* (int)ctl. The ec field is never accessed alone, but always |
476 |
> |
* together with id and st. The offsets of counts by the target |
477 |
> |
* parallelism and the positionings of fields makes it possible to |
478 |
> |
* perform the most common checks via sign tests of fields: When |
479 |
> |
* ac is negative, there are not enough active workers, when tc is |
480 |
> |
* negative, there are not enough total workers, when id is |
481 |
> |
* negative, there is at least one waiting worker, and when e is |
482 |
> |
* negative, the pool is terminating. To deal with these possibly |
483 |
> |
* negative fields, we use casts in and out of "short" and/or |
484 |
> |
* signed shifts to maintain signedness. |
485 |
|
*/ |
486 |
< |
private volatile WaitQueueNode syncStack; |
486 |
> |
volatile long ctl; |
487 |
> |
|
488 |
> |
// bit positions/shifts for fields |
489 |
> |
private static final int AC_SHIFT = 48; |
490 |
> |
private static final int TC_SHIFT = 32; |
491 |
> |
private static final int ST_SHIFT = 31; |
492 |
> |
private static final int EC_SHIFT = 16; |
493 |
> |
|
494 |
> |
// bounds |
495 |
> |
private static final int MAX_ID = 0x7fff; // max poolIndex |
496 |
> |
private static final int SMASK = 0xffff; // mask short bits |
497 |
> |
private static final int SHORT_SIGN = 1 << 15; |
498 |
> |
private static final int INT_SIGN = 1 << 31; |
499 |
> |
|
500 |
> |
// masks |
501 |
> |
private static final long STOP_BIT = 0x0001L << ST_SHIFT; |
502 |
> |
private static final long AC_MASK = ((long)SMASK) << AC_SHIFT; |
503 |
> |
private static final long TC_MASK = ((long)SMASK) << TC_SHIFT; |
504 |
> |
|
505 |
> |
// units for incrementing and decrementing |
506 |
> |
private static final long TC_UNIT = 1L << TC_SHIFT; |
507 |
> |
private static final long AC_UNIT = 1L << AC_SHIFT; |
508 |
> |
|
509 |
> |
// masks and units for dealing with u = (int)(ctl >>> 32) |
510 |
> |
private static final int UAC_SHIFT = AC_SHIFT - 32; |
511 |
> |
private static final int UTC_SHIFT = TC_SHIFT - 32; |
512 |
> |
private static final int UAC_MASK = SMASK << UAC_SHIFT; |
513 |
> |
private static final int UTC_MASK = SMASK << UTC_SHIFT; |
514 |
> |
private static final int UAC_UNIT = 1 << UAC_SHIFT; |
515 |
> |
private static final int UTC_UNIT = 1 << UTC_SHIFT; |
516 |
> |
|
517 |
> |
// masks and units for dealing with e = (int)ctl |
518 |
> |
private static final int E_MASK = 0x7fffffff; // no STOP_BIT |
519 |
> |
private static final int EC_UNIT = 1 << EC_SHIFT; |
520 |
|
|
521 |
|
/** |
522 |
< |
* The count for event barrier |
522 |
> |
* The target parallelism level. |
523 |
|
*/ |
524 |
< |
private volatile long eventCount; |
524 |
> |
final int parallelism; |
525 |
|
|
526 |
|
/** |
527 |
< |
* Pool number, just for assigning useful names to worker threads |
527 |
> |
* Index (mod submission queue length) of next element to take |
528 |
> |
* from submission queue. Usage is identical to that for |
529 |
> |
* per-worker queues -- see ForkJoinWorkerThread internal |
530 |
> |
* documentation. |
531 |
|
*/ |
532 |
< |
private final int poolNumber; |
532 |
> |
volatile int queueBase; |
533 |
|
|
534 |
|
/** |
535 |
< |
* The maximum allowed pool size |
535 |
> |
* Index (mod submission queue length) of next element to add |
536 |
> |
* in submission queue. Usage is identical to that for |
537 |
> |
* per-worker queues -- see ForkJoinWorkerThread internal |
538 |
> |
* documentation. |
539 |
|
*/ |
540 |
< |
private volatile int maxPoolSize; |
540 |
> |
int queueTop; |
541 |
|
|
542 |
|
/** |
543 |
< |
* The desired parallelism level, updated only under workerLock. |
543 |
> |
* True when shutdown() has been called. |
544 |
|
*/ |
545 |
< |
private volatile int parallelism; |
545 |
> |
volatile boolean shutdown; |
546 |
|
|
547 |
|
/** |
548 |
|
* True if use local fifo, not default lifo, for local polling |
549 |
+ |
* Read by, and replicated by ForkJoinWorkerThreads |
550 |
|
*/ |
551 |
< |
private volatile boolean locallyFifo; |
551 |
> |
final boolean locallyFifo; |
552 |
|
|
553 |
|
/** |
554 |
< |
* Holds number of total (i.e., created and not yet terminated) |
555 |
< |
* and running (i.e., not blocked on joins or other managed sync) |
556 |
< |
* threads, packed into one int to ensure consistent snapshot when |
227 |
< |
* making decisions about creating and suspending spare |
228 |
< |
* threads. Updated only by CAS. Note: CASes in |
229 |
< |
* updateRunningCount and preJoin assume that running active count |
230 |
< |
* is in low word, so need to be modified if this changes. |
554 |
> |
* The number of threads in ForkJoinWorkerThreads.helpQuiescePool. |
555 |
> |
* When non-zero, suppresses automatic shutdown when active |
556 |
> |
* counts become zero. |
557 |
|
*/ |
558 |
< |
private volatile int workerCounts; |
558 |
> |
volatile int quiescerCount; |
559 |
|
|
560 |
< |
private static int totalCountOf(int s) { return s >>> 16; } |
561 |
< |
private static int runningCountOf(int s) { return s & shortMask; } |
562 |
< |
private static int workerCountsFor(int t, int r) { return (t << 16) + r; } |
560 |
> |
/** |
561 |
> |
* The number of threads blocked in join. |
562 |
> |
*/ |
563 |
> |
volatile int blockedCount; |
564 |
|
|
565 |
|
/** |
566 |
< |
* Adds delta (which may be negative) to running count. This must |
240 |
< |
* be called before (with negative arg) and after (with positive) |
241 |
< |
* any managed synchronization (i.e., mainly, joins). |
242 |
< |
* |
243 |
< |
* @param delta the number to add |
566 |
> |
* Counter for worker Thread names (unrelated to their poolIndex) |
567 |
|
*/ |
568 |
< |
final void updateRunningCount(int delta) { |
246 |
< |
int s; |
247 |
< |
do {} while (!casWorkerCounts(s = workerCounts, s + delta)); |
248 |
< |
} |
568 |
> |
private volatile int nextWorkerNumber; |
569 |
|
|
570 |
|
/** |
571 |
< |
* Adds delta (which may be negative) to both total and running |
252 |
< |
* count. This must be called upon creation and termination of |
253 |
< |
* worker threads. |
254 |
< |
* |
255 |
< |
* @param delta the number to add |
571 |
> |
* The index for the next created worker. Accessed under scanGuard. |
572 |
|
*/ |
573 |
< |
private void updateWorkerCount(int delta) { |
258 |
< |
int d = delta + (delta << 16); // add to both lo and hi parts |
259 |
< |
int s; |
260 |
< |
do {} while (!casWorkerCounts(s = workerCounts, s + d)); |
261 |
< |
} |
573 |
> |
private int nextWorkerIndex; |
574 |
|
|
575 |
|
/** |
576 |
< |
* Lifecycle control. High word contains runState, low word |
577 |
< |
* contains the number of workers that are (probably) executing |
578 |
< |
* tasks. This value is atomically incremented before a worker |
579 |
< |
* gets a task to run, and decremented when worker has no tasks |
580 |
< |
* and cannot find any. These two fields are bundled together to |
581 |
< |
* support correct termination triggering. Note: activeCount |
582 |
< |
* CAS'es cheat by assuming active count is in low word, so need |
583 |
< |
* to be modified if this changes |
576 |
> |
* SeqLock and index masking for updates to workers array. Locked |
577 |
> |
* when SG_UNIT is set. Unlocking clears bit by adding |
578 |
> |
* SG_UNIT. Staleness of read-only operations can be checked by |
579 |
> |
* comparing scanGuard to value before the reads. The low 16 bits |
580 |
> |
* (i.e, anding with SMASK) hold (the smallest power of two |
581 |
> |
* covering all worker indices, minus one, and is used to avoid |
582 |
> |
* dealing with large numbers of null slots when the workers array |
583 |
> |
* is overallocated. |
584 |
|
*/ |
585 |
< |
private volatile int runControl; |
585 |
> |
volatile int scanGuard; |
586 |
|
|
587 |
< |
// RunState values. Order among values matters |
276 |
< |
private static final int RUNNING = 0; |
277 |
< |
private static final int SHUTDOWN = 1; |
278 |
< |
private static final int TERMINATING = 2; |
279 |
< |
private static final int TERMINATED = 3; |
587 |
> |
private static final int SG_UNIT = 1 << 16; |
588 |
|
|
589 |
< |
private static int runStateOf(int c) { return c >>> 16; } |
590 |
< |
private static int activeCountOf(int c) { return c & shortMask; } |
591 |
< |
private static int runControlFor(int r, int a) { return (r << 16) + a; } |
589 |
> |
/** |
590 |
> |
* The wakeup interval (in nanoseconds) for a worker waiting for a |
591 |
> |
* task when the pool is quiescent to instead try to shrink the |
592 |
> |
* number of workers. The exact value does not matter too |
593 |
> |
* much. It must be short enough to release resources during |
594 |
> |
* sustained periods of idleness, but not so short that threads |
595 |
> |
* are continually re-created. |
596 |
> |
*/ |
597 |
> |
private static final long SHRINK_RATE = |
598 |
> |
4L * 1000L * 1000L * 1000L; // 4 seconds |
599 |
|
|
600 |
|
/** |
601 |
< |
* Tries incrementing active count; fails on contention. |
602 |
< |
* Called by workers before/during executing tasks. |
601 |
> |
* Top-level loop for worker threads: On each step: if the |
602 |
> |
* previous step swept through all queues and found no tasks, or |
603 |
> |
* there are excess threads, then possibly blocks. Otherwise, |
604 |
> |
* scans for and, if found, executes a task. Returns when pool |
605 |
> |
* and/or worker terminate. |
606 |
|
* |
607 |
< |
* @return true on success |
607 |
> |
* @param w the worker |
608 |
|
*/ |
609 |
< |
final boolean tryIncrementActiveCount() { |
610 |
< |
int c = runControl; |
611 |
< |
return casRunControl(c, c+1); |
609 |
> |
final void work(ForkJoinWorkerThread w) { |
610 |
> |
boolean swept = false; // true on empty scans |
611 |
> |
long c; |
612 |
> |
while (!w.terminate && (int)(c = ctl) >= 0) { |
613 |
> |
int a; // active count |
614 |
> |
if (!swept && (a = (int)(c >> AC_SHIFT)) <= 0) |
615 |
> |
swept = scan(w, a); |
616 |
> |
else if (tryAwaitWork(w, c)) |
617 |
> |
swept = false; |
618 |
> |
} |
619 |
|
} |
620 |
|
|
621 |
+ |
// Signalling |
622 |
+ |
|
623 |
|
/** |
624 |
< |
* Tries decrementing active count; fails on contention. |
298 |
< |
* Possibly triggers termination on success. |
299 |
< |
* Called by workers when they can't find tasks. |
300 |
< |
* |
301 |
< |
* @return true on success |
624 |
> |
* Wakes up or creates a worker. |
625 |
|
*/ |
626 |
< |
final boolean tryDecrementActiveCount() { |
627 |
< |
int c = runControl; |
628 |
< |
int nextc = c - 1; |
629 |
< |
if (!casRunControl(c, nextc)) |
630 |
< |
return false; |
631 |
< |
if (canTerminateOnShutdown(nextc)) |
632 |
< |
terminateOnShutdown(); |
633 |
< |
return true; |
626 |
> |
final void signalWork() { |
627 |
> |
/* |
628 |
> |
* The while condition is true if: (there is are too few total |
629 |
> |
* workers OR there is at least one waiter) AND (there are too |
630 |
> |
* few active workers OR the pool is terminating). The value |
631 |
> |
* of e distinguishes the remaining cases: zero (no waiters) |
632 |
> |
* for create, negative if terminating (in which case do |
633 |
> |
* nothing), else release a waiter. The secondary checks for |
634 |
> |
* release (non-null array etc) can fail if the pool begins |
635 |
> |
* terminating after the test, and don't impose any added cost |
636 |
> |
* because JVMs must perform null and bounds checks anyway. |
637 |
> |
*/ |
638 |
> |
long c; int e, u; |
639 |
> |
while ((((e = (int)(c = ctl)) | (u = (int)(c >>> 32))) & |
640 |
> |
(INT_SIGN|SHORT_SIGN)) == (INT_SIGN|SHORT_SIGN) && e >= 0) { |
641 |
> |
if (e > 0) { // release a waiting worker |
642 |
> |
int i; ForkJoinWorkerThread w; ForkJoinWorkerThread[] ws; |
643 |
> |
if ((ws = workers) == null || |
644 |
> |
(i = ~e & SMASK) >= ws.length || |
645 |
> |
(w = ws[i]) == null) |
646 |
> |
break; |
647 |
> |
long nc = (((long)(w.nextWait & E_MASK)) | |
648 |
> |
((long)(u + UAC_UNIT) << 32)); |
649 |
> |
if (w.eventCount == e && |
650 |
> |
UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
651 |
> |
w.eventCount = (e + EC_UNIT) & E_MASK; |
652 |
> |
if (w.parked) |
653 |
> |
UNSAFE.unpark(w); |
654 |
> |
break; |
655 |
> |
} |
656 |
> |
} |
657 |
> |
else if (UNSAFE.compareAndSwapLong |
658 |
> |
(this, ctlOffset, c, |
659 |
> |
(long)(((u + UTC_UNIT) & UTC_MASK) | |
660 |
> |
((u + UAC_UNIT) & UAC_MASK)) << 32)) { |
661 |
> |
addWorker(); |
662 |
> |
break; |
663 |
> |
} |
664 |
> |
} |
665 |
|
} |
666 |
|
|
667 |
|
/** |
668 |
< |
* Returns true if argument represents zero active count and |
669 |
< |
* nonzero runstate, which is the triggering condition for |
670 |
< |
* terminating on shutdown. |
668 |
> |
* Variant of signalWork to help release waiters on rescans. |
669 |
> |
* Tries once to release a waiter if active count < 0. |
670 |
> |
* |
671 |
> |
* @return false if failed due to contention, else true |
672 |
|
*/ |
673 |
< |
private static boolean canTerminateOnShutdown(int c) { |
674 |
< |
// i.e. least bit is nonzero runState bit |
675 |
< |
return ((c & -c) >>> 16) != 0; |
673 |
> |
private boolean tryReleaseWaiter() { |
674 |
> |
long c; int e, i; ForkJoinWorkerThread w; ForkJoinWorkerThread[] ws; |
675 |
> |
if ((e = (int)(c = ctl)) > 0 && |
676 |
> |
(int)(c >> AC_SHIFT) < 0 && |
677 |
> |
(ws = workers) != null && |
678 |
> |
(i = ~e & SMASK) < ws.length && |
679 |
> |
(w = ws[i]) != null) { |
680 |
> |
long nc = ((long)(w.nextWait & E_MASK) | |
681 |
> |
((c + AC_UNIT) & (AC_MASK|TC_MASK))); |
682 |
> |
if (w.eventCount != e || |
683 |
> |
!UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) |
684 |
> |
return false; |
685 |
> |
w.eventCount = (e + EC_UNIT) & E_MASK; |
686 |
> |
if (w.parked) |
687 |
> |
UNSAFE.unpark(w); |
688 |
> |
} |
689 |
> |
return true; |
690 |
|
} |
691 |
|
|
692 |
+ |
// Scanning for tasks |
693 |
+ |
|
694 |
|
/** |
695 |
< |
* Transition run state to at least the given state. Return true |
696 |
< |
* if not already at least given state. |
695 |
> |
* Scans for and, if found, executes one task. Scans start at a |
696 |
> |
* random index of workers array, and randomly select the first |
697 |
> |
* (2*#workers)-1 probes, and then, if all empty, resort to 2 |
698 |
> |
* circular sweeps, which is necessary to check quiescence. and |
699 |
> |
* taking a submission only if no stealable tasks were found. The |
700 |
> |
* steal code inside the loop is a specialized form of |
701 |
> |
* ForkJoinWorkerThread.deqTask, followed bookkeeping to support |
702 |
> |
* helpJoinTask and signal propagation. The code for submission |
703 |
> |
* queues is almost identical. On each steal, the worker completes |
704 |
> |
* not only the task, but also all local tasks that this task may |
705 |
> |
* have generated. On detecting staleness or contention when |
706 |
> |
* trying to take a task, this method returns without finishing |
707 |
> |
* sweep, which allows global state rechecks before retry. |
708 |
> |
* |
709 |
> |
* @param w the worker |
710 |
> |
* @param a the number of active workers |
711 |
> |
* @return true if swept all queues without finding a task |
712 |
|
*/ |
713 |
< |
private boolean transitionRunStateTo(int state) { |
714 |
< |
for (;;) { |
715 |
< |
int c = runControl; |
716 |
< |
if (runStateOf(c) >= state) |
713 |
> |
private boolean scan(ForkJoinWorkerThread w, int a) { |
714 |
> |
int g = scanGuard; // mask 0 avoids useless scans if only one active |
715 |
> |
int m = (parallelism == 1 - a && blockedCount == 0) ? 0 : g & SMASK; |
716 |
> |
ForkJoinWorkerThread[] ws = workers; |
717 |
> |
if (ws == null || ws.length <= m) // staleness check |
718 |
> |
return false; |
719 |
> |
for (int r = w.seed, k = r, j = -(m + m); j <= m + m; ++j) { |
720 |
> |
ForkJoinTask<?> t; ForkJoinTask<?>[] q; int b, i; |
721 |
> |
ForkJoinWorkerThread v = ws[k & m]; |
722 |
> |
if (v != null && (b = v.queueBase) != v.queueTop && |
723 |
> |
(q = v.queue) != null && (i = (q.length - 1) & b) >= 0) { |
724 |
> |
long u = (i << ASHIFT) + ABASE; |
725 |
> |
if ((t = q[i]) != null && v.queueBase == b && |
726 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
727 |
> |
int d = (v.queueBase = b + 1) - v.queueTop; |
728 |
> |
v.stealHint = w.poolIndex; |
729 |
> |
if (d != 0) |
730 |
> |
signalWork(); // propagate if nonempty |
731 |
> |
w.execTask(t); |
732 |
> |
} |
733 |
> |
r ^= r << 13; r ^= r >>> 17; w.seed = r ^ (r << 5); |
734 |
> |
return false; // store next seed |
735 |
> |
} |
736 |
> |
else if (j < 0) { // xorshift |
737 |
> |
r ^= r << 13; r ^= r >>> 17; k = r ^= r << 5; |
738 |
> |
} |
739 |
> |
else |
740 |
> |
++k; |
741 |
> |
} |
742 |
> |
if (scanGuard != g) // staleness check |
743 |
> |
return false; |
744 |
> |
else { // try to take submission |
745 |
> |
ForkJoinTask<?> t; ForkJoinTask<?>[] q; int b, i; |
746 |
> |
if ((b = queueBase) != queueTop && |
747 |
> |
(q = submissionQueue) != null && |
748 |
> |
(i = (q.length - 1) & b) >= 0) { |
749 |
> |
long u = (i << ASHIFT) + ABASE; |
750 |
> |
if ((t = q[i]) != null && queueBase == b && |
751 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
752 |
> |
queueBase = b + 1; |
753 |
> |
w.execTask(t); |
754 |
> |
} |
755 |
|
return false; |
756 |
< |
if (casRunControl(c, runControlFor(state, activeCountOf(c)))) |
756 |
> |
} |
757 |
> |
return true; // all queues empty |
758 |
> |
} |
759 |
> |
} |
760 |
> |
|
761 |
> |
/** |
762 |
> |
* Tries to enqueue worker w in wait queue and await change in |
763 |
> |
* worker's eventCount. If the pool is quiescent and there is |
764 |
> |
* more than one worker, possibly terminates worker upon exit. |
765 |
> |
* Otherwise, before blocking, rescans queues to avoid missed |
766 |
> |
* signals. Upon finding work, releases at least one worker |
767 |
> |
* (which may be the current worker). Rescans restart upon |
768 |
> |
* detected staleness or failure to release due to |
769 |
> |
* contention. Note the unusual conventions about Thread.interrupt |
770 |
> |
* here and elsewhere: Because interrupts are used solely to alert |
771 |
> |
* threads to check termination, which is checked here anyway, we |
772 |
> |
* clear status (using Thread.interrupted) before any call to |
773 |
> |
* park, so that park does not immediately return due to status |
774 |
> |
* being set via some other unrelated call to interrupt in user |
775 |
> |
* code. |
776 |
> |
* |
777 |
> |
* @param w the calling worker |
778 |
> |
* @param c the ctl value on entry |
779 |
> |
* @return true if waited or another thread was released upon enq |
780 |
> |
*/ |
781 |
> |
private boolean tryAwaitWork(ForkJoinWorkerThread w, long c) { |
782 |
> |
int v = w.eventCount; |
783 |
> |
w.nextWait = (int)c; // w's successor record |
784 |
> |
long nc = (long)(v & E_MASK) | ((c - AC_UNIT) & (AC_MASK|TC_MASK)); |
785 |
> |
if (ctl != c || !UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
786 |
> |
long d = ctl; // return true if lost to a deq, to force scan |
787 |
> |
return (int)d != (int)c && ((d - c) & AC_MASK) >= 0L; |
788 |
> |
} |
789 |
> |
for (int sc = w.stealCount; sc != 0;) { // accumulate stealCount |
790 |
> |
long s = stealCount; |
791 |
> |
if (UNSAFE.compareAndSwapLong(this, stealCountOffset, s, s + sc)) |
792 |
> |
sc = w.stealCount = 0; |
793 |
> |
else if (w.eventCount != v) |
794 |
> |
return true; // update next time |
795 |
> |
} |
796 |
> |
if ((!shutdown || !tryTerminate(false)) && |
797 |
> |
(int)c != 0 && parallelism + (int)(nc >> AC_SHIFT) == 0 && |
798 |
> |
blockedCount == 0 && quiescerCount == 0) |
799 |
> |
idleAwaitWork(w, nc, c, v); // quiescent |
800 |
> |
for (boolean rescanned = false;;) { |
801 |
> |
if (w.eventCount != v) |
802 |
|
return true; |
803 |
+ |
if (!rescanned) { |
804 |
+ |
int g = scanGuard, m = g & SMASK; |
805 |
+ |
ForkJoinWorkerThread[] ws = workers; |
806 |
+ |
if (ws != null && m < ws.length) { |
807 |
+ |
rescanned = true; |
808 |
+ |
for (int i = 0; i <= m; ++i) { |
809 |
+ |
ForkJoinWorkerThread u = ws[i]; |
810 |
+ |
if (u != null) { |
811 |
+ |
if (u.queueBase != u.queueTop && |
812 |
+ |
!tryReleaseWaiter()) |
813 |
+ |
rescanned = false; // contended |
814 |
+ |
if (w.eventCount != v) |
815 |
+ |
return true; |
816 |
+ |
} |
817 |
+ |
} |
818 |
+ |
} |
819 |
+ |
if (scanGuard != g || // stale |
820 |
+ |
(queueBase != queueTop && !tryReleaseWaiter())) |
821 |
+ |
rescanned = false; |
822 |
+ |
if (!rescanned) |
823 |
+ |
Thread.yield(); // reduce contention |
824 |
+ |
else |
825 |
+ |
Thread.interrupted(); // clear before park |
826 |
+ |
} |
827 |
+ |
else { |
828 |
+ |
w.parked = true; // must recheck |
829 |
+ |
if (w.eventCount != v) { |
830 |
+ |
w.parked = false; |
831 |
+ |
return true; |
832 |
+ |
} |
833 |
+ |
LockSupport.park(this); |
834 |
+ |
rescanned = w.parked = false; |
835 |
+ |
} |
836 |
|
} |
837 |
|
} |
838 |
|
|
839 |
|
/** |
840 |
< |
* Controls whether to add spares to maintain parallelism |
841 |
< |
*/ |
842 |
< |
private volatile boolean maintainsParallelism; |
840 |
> |
* If inactivating worker w has caused pool to become |
841 |
> |
* quiescent, check for pool termination, and wait for event |
842 |
> |
* for up to SHRINK_RATE nanosecs (rescans are unnecessary in |
843 |
> |
* this case because quiescence reflects consensus about lack |
844 |
> |
* of work). On timeout, if ctl has not changed, terminate the |
845 |
> |
* worker. Upon its termination (see deregisterWorker), it may |
846 |
> |
* wake up another worker to possibly repeat this process. |
847 |
> |
* |
848 |
> |
* @param w the calling worker |
849 |
> |
* @param currentCtl the ctl value after enqueuing w |
850 |
> |
* @param prevCtl the ctl value if w terminated |
851 |
> |
* @param v the eventCount w awaits change |
852 |
> |
*/ |
853 |
> |
private void idleAwaitWork(ForkJoinWorkerThread w, long currentCtl, |
854 |
> |
long prevCtl, int v) { |
855 |
> |
if (w.eventCount == v) { |
856 |
> |
if (shutdown) |
857 |
> |
tryTerminate(false); |
858 |
> |
ForkJoinTask.helpExpungeStaleExceptions(); // help clean weak refs |
859 |
> |
while (ctl == currentCtl) { |
860 |
> |
long startTime = System.nanoTime(); |
861 |
> |
w.parked = true; |
862 |
> |
if (w.eventCount == v) // must recheck |
863 |
> |
LockSupport.parkNanos(this, SHRINK_RATE); |
864 |
> |
w.parked = false; |
865 |
> |
if (w.eventCount != v) |
866 |
> |
break; |
867 |
> |
else if (System.nanoTime() - startTime < |
868 |
> |
SHRINK_RATE - (SHRINK_RATE / 10)) // timing slop |
869 |
> |
Thread.interrupted(); // spurious wakeup |
870 |
> |
else if (UNSAFE.compareAndSwapLong(this, ctlOffset, |
871 |
> |
currentCtl, prevCtl)) { |
872 |
> |
w.terminate = true; // restore previous |
873 |
> |
w.eventCount = ((int)currentCtl + EC_UNIT) & E_MASK; |
874 |
> |
break; |
875 |
> |
} |
876 |
> |
} |
877 |
> |
} |
878 |
> |
} |
879 |
|
|
880 |
< |
// Constructors |
880 |
> |
// Submissions |
881 |
|
|
882 |
|
/** |
883 |
< |
* Creates a ForkJoinPool with a pool size equal to the number of |
884 |
< |
* processors available on the system, using the default |
347 |
< |
* ForkJoinWorkerThreadFactory. |
883 |
> |
* Enqueues the given task in the submissionQueue. Same idea as |
884 |
> |
* ForkJoinWorkerThread.pushTask except for use of submissionLock. |
885 |
|
* |
886 |
< |
* @throws SecurityException if a security manager exists and |
350 |
< |
* the caller is not permitted to modify threads |
351 |
< |
* because it does not hold {@link |
352 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
886 |
> |
* @param t the task |
887 |
|
*/ |
888 |
< |
public ForkJoinPool() { |
889 |
< |
this(Runtime.getRuntime().availableProcessors(), |
890 |
< |
defaultForkJoinWorkerThreadFactory); |
888 |
> |
private void addSubmission(ForkJoinTask<?> t) { |
889 |
> |
final ReentrantLock lock = this.submissionLock; |
890 |
> |
lock.lock(); |
891 |
> |
try { |
892 |
> |
ForkJoinTask<?>[] q; int s, m; |
893 |
> |
if ((q = submissionQueue) != null) { // ignore if queue removed |
894 |
> |
long u = (((s = queueTop) & (m = q.length-1)) << ASHIFT)+ABASE; |
895 |
> |
UNSAFE.putOrderedObject(q, u, t); |
896 |
> |
queueTop = s + 1; |
897 |
> |
if (s - queueBase == m) |
898 |
> |
growSubmissionQueue(); |
899 |
> |
} |
900 |
> |
} finally { |
901 |
> |
lock.unlock(); |
902 |
> |
} |
903 |
> |
signalWork(); |
904 |
|
} |
905 |
|
|
906 |
+ |
// (pollSubmission is defined below with exported methods) |
907 |
+ |
|
908 |
|
/** |
909 |
< |
* Creates a ForkJoinPool with the indicated parallelism level |
910 |
< |
* threads and using the default ForkJoinWorkerThreadFactory. |
362 |
< |
* |
363 |
< |
* @param parallelism the number of worker threads |
364 |
< |
* @throws IllegalArgumentException if parallelism less than or |
365 |
< |
* equal to zero |
366 |
< |
* @throws SecurityException if a security manager exists and |
367 |
< |
* the caller is not permitted to modify threads |
368 |
< |
* because it does not hold {@link |
369 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
909 |
> |
* Creates or doubles submissionQueue array. |
910 |
> |
* Basically identical to ForkJoinWorkerThread version. |
911 |
|
*/ |
912 |
< |
public ForkJoinPool(int parallelism) { |
913 |
< |
this(parallelism, defaultForkJoinWorkerThreadFactory); |
912 |
> |
private void growSubmissionQueue() { |
913 |
> |
ForkJoinTask<?>[] oldQ = submissionQueue; |
914 |
> |
int size = oldQ != null ? oldQ.length << 1 : INITIAL_QUEUE_CAPACITY; |
915 |
> |
if (size > MAXIMUM_QUEUE_CAPACITY) |
916 |
> |
throw new RejectedExecutionException("Queue capacity exceeded"); |
917 |
> |
if (size < INITIAL_QUEUE_CAPACITY) |
918 |
> |
size = INITIAL_QUEUE_CAPACITY; |
919 |
> |
ForkJoinTask<?>[] q = submissionQueue = new ForkJoinTask<?>[size]; |
920 |
> |
int mask = size - 1; |
921 |
> |
int top = queueTop; |
922 |
> |
int oldMask; |
923 |
> |
if (oldQ != null && (oldMask = oldQ.length - 1) >= 0) { |
924 |
> |
for (int b = queueBase; b != top; ++b) { |
925 |
> |
long u = ((b & oldMask) << ASHIFT) + ABASE; |
926 |
> |
Object x = UNSAFE.getObjectVolatile(oldQ, u); |
927 |
> |
if (x != null && UNSAFE.compareAndSwapObject(oldQ, u, x, null)) |
928 |
> |
UNSAFE.putObjectVolatile |
929 |
> |
(q, ((b & mask) << ASHIFT) + ABASE, x); |
930 |
> |
} |
931 |
> |
} |
932 |
> |
} |
933 |
> |
|
934 |
> |
// Blocking support |
935 |
> |
|
936 |
> |
/** |
937 |
> |
* Tries to increment blockedCount, decrement active count |
938 |
> |
* (sometimes implicitly) and possibly release or create a |
939 |
> |
* compensating worker in preparation for blocking. Fails |
940 |
> |
* on contention or termination. |
941 |
> |
* |
942 |
> |
* @return true if the caller can block, else should recheck and retry |
943 |
> |
*/ |
944 |
> |
private boolean tryPreBlock() { |
945 |
> |
int b = blockedCount; |
946 |
> |
if (UNSAFE.compareAndSwapInt(this, blockedCountOffset, b, b + 1)) { |
947 |
> |
int pc = parallelism; |
948 |
> |
do { |
949 |
> |
ForkJoinWorkerThread[] ws; ForkJoinWorkerThread w; |
950 |
> |
int e, ac, tc, i; |
951 |
> |
long c = ctl; |
952 |
> |
int u = (int)(c >>> 32); |
953 |
> |
if ((e = (int)c) < 0) { |
954 |
> |
// skip -- terminating |
955 |
> |
} |
956 |
> |
else if ((ac = (u >> UAC_SHIFT)) <= 0 && e != 0 && |
957 |
> |
(ws = workers) != null && |
958 |
> |
(i = ~e & SMASK) < ws.length && |
959 |
> |
(w = ws[i]) != null) { |
960 |
> |
long nc = ((long)(w.nextWait & E_MASK) | |
961 |
> |
(c & (AC_MASK|TC_MASK))); |
962 |
> |
if (w.eventCount == e && |
963 |
> |
UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
964 |
> |
w.eventCount = (e + EC_UNIT) & E_MASK; |
965 |
> |
if (w.parked) |
966 |
> |
UNSAFE.unpark(w); |
967 |
> |
return true; // release an idle worker |
968 |
> |
} |
969 |
> |
} |
970 |
> |
else if ((tc = (short)(u >>> UTC_SHIFT)) >= 0 && ac + pc > 1) { |
971 |
> |
long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK); |
972 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) |
973 |
> |
return true; // no compensation needed |
974 |
> |
} |
975 |
> |
else if (tc + pc < MAX_ID) { |
976 |
> |
long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK); |
977 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
978 |
> |
addWorker(); |
979 |
> |
return true; // create a replacement |
980 |
> |
} |
981 |
> |
} |
982 |
> |
// try to back out on any failure and let caller retry |
983 |
> |
} while (!UNSAFE.compareAndSwapInt(this, blockedCountOffset, |
984 |
> |
b = blockedCount, b - 1)); |
985 |
> |
} |
986 |
> |
return false; |
987 |
|
} |
988 |
|
|
989 |
|
/** |
990 |
< |
* Creates a ForkJoinPool with parallelism equal to the number of |
377 |
< |
* processors available on the system and using the given |
378 |
< |
* ForkJoinWorkerThreadFactory. |
379 |
< |
* |
380 |
< |
* @param factory the factory for creating new threads |
381 |
< |
* @throws NullPointerException if factory is null |
382 |
< |
* @throws SecurityException if a security manager exists and |
383 |
< |
* the caller is not permitted to modify threads |
384 |
< |
* because it does not hold {@link |
385 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
990 |
> |
* Decrements blockedCount and increments active count. |
991 |
|
*/ |
992 |
< |
public ForkJoinPool(ForkJoinWorkerThreadFactory factory) { |
993 |
< |
this(Runtime.getRuntime().availableProcessors(), factory); |
992 |
> |
private void postBlock() { |
993 |
> |
long c; |
994 |
> |
do {} while (!UNSAFE.compareAndSwapLong(this, ctlOffset, // no mask |
995 |
> |
c = ctl, c + AC_UNIT)); |
996 |
> |
int b; |
997 |
> |
do {} while (!UNSAFE.compareAndSwapInt(this, blockedCountOffset, |
998 |
> |
b = blockedCount, b - 1)); |
999 |
|
} |
1000 |
|
|
1001 |
|
/** |
1002 |
< |
* Creates a ForkJoinPool with the given parallelism and factory. |
1002 |
> |
* Possibly blocks waiting for the given task to complete, or |
1003 |
> |
* cancels the task if terminating. Fails to wait if contended. |
1004 |
|
* |
1005 |
< |
* @param parallelism the targeted number of worker threads |
395 |
< |
* @param factory the factory for creating new threads |
396 |
< |
* @throws IllegalArgumentException if parallelism less than or |
397 |
< |
* equal to zero, or greater than implementation limit |
398 |
< |
* @throws NullPointerException if factory is null |
399 |
< |
* @throws SecurityException if a security manager exists and |
400 |
< |
* the caller is not permitted to modify threads |
401 |
< |
* because it does not hold {@link |
402 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1005 |
> |
* @param joinMe the task |
1006 |
|
*/ |
1007 |
< |
public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) { |
1008 |
< |
if (parallelism <= 0 || parallelism > MAX_THREADS) |
1009 |
< |
throw new IllegalArgumentException(); |
1010 |
< |
if (factory == null) |
1011 |
< |
throw new NullPointerException(); |
1012 |
< |
checkPermission(); |
1013 |
< |
this.factory = factory; |
1014 |
< |
this.parallelism = parallelism; |
1015 |
< |
this.maxPoolSize = MAX_THREADS; |
1016 |
< |
this.maintainsParallelism = true; |
414 |
< |
this.poolNumber = poolNumberGenerator.incrementAndGet(); |
415 |
< |
this.workerLock = new ReentrantLock(); |
416 |
< |
this.termination = workerLock.newCondition(); |
417 |
< |
this.stealCount = new AtomicLong(); |
418 |
< |
this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>(); |
419 |
< |
// worker array and workers are lazily constructed |
1007 |
> |
final void tryAwaitJoin(ForkJoinTask<?> joinMe) { |
1008 |
> |
Thread.interrupted(); // clear interrupts before checking termination |
1009 |
> |
if (joinMe.status >= 0) { |
1010 |
> |
if (tryPreBlock()) { |
1011 |
> |
joinMe.tryAwaitDone(0L); |
1012 |
> |
postBlock(); |
1013 |
> |
} |
1014 |
> |
else if ((ctl & STOP_BIT) != 0L) |
1015 |
> |
joinMe.cancelIgnoringExceptions(); |
1016 |
> |
} |
1017 |
|
} |
1018 |
|
|
1019 |
|
/** |
1020 |
< |
* Creates a new worker thread using factory. |
1020 |
> |
* Possibly blocks the given worker waiting for joinMe to |
1021 |
> |
* complete or timeout. |
1022 |
|
* |
1023 |
< |
* @param index the index to assign worker |
1024 |
< |
* @return new worker, or null of factory failed |
1023 |
> |
* @param joinMe the task |
1024 |
> |
* @param millis the wait time for underlying Object.wait |
1025 |
|
*/ |
1026 |
< |
private ForkJoinWorkerThread createWorker(int index) { |
1027 |
< |
Thread.UncaughtExceptionHandler h = ueh; |
1028 |
< |
ForkJoinWorkerThread w = factory.newThread(this); |
1029 |
< |
if (w != null) { |
1030 |
< |
w.poolIndex = index; |
1031 |
< |
w.setDaemon(true); |
1032 |
< |
w.setAsyncMode(locallyFifo); |
1033 |
< |
w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index); |
1034 |
< |
if (h != null) |
1035 |
< |
w.setUncaughtExceptionHandler(h); |
1026 |
> |
final void timedAwaitJoin(ForkJoinTask<?> joinMe, long nanos) { |
1027 |
> |
while (joinMe.status >= 0) { |
1028 |
> |
Thread.interrupted(); |
1029 |
> |
if ((ctl & STOP_BIT) != 0L) { |
1030 |
> |
joinMe.cancelIgnoringExceptions(); |
1031 |
> |
break; |
1032 |
> |
} |
1033 |
> |
if (tryPreBlock()) { |
1034 |
> |
long last = System.nanoTime(); |
1035 |
> |
while (joinMe.status >= 0) { |
1036 |
> |
long millis = TimeUnit.NANOSECONDS.toMillis(nanos); |
1037 |
> |
if (millis <= 0) |
1038 |
> |
break; |
1039 |
> |
joinMe.tryAwaitDone(millis); |
1040 |
> |
if (joinMe.status < 0) |
1041 |
> |
break; |
1042 |
> |
if ((ctl & STOP_BIT) != 0L) { |
1043 |
> |
joinMe.cancelIgnoringExceptions(); |
1044 |
> |
break; |
1045 |
> |
} |
1046 |
> |
long now = System.nanoTime(); |
1047 |
> |
nanos -= now - last; |
1048 |
> |
last = now; |
1049 |
> |
} |
1050 |
> |
postBlock(); |
1051 |
> |
break; |
1052 |
> |
} |
1053 |
|
} |
439 |
– |
return w; |
1054 |
|
} |
1055 |
|
|
1056 |
|
/** |
1057 |
< |
* Returns a good size for worker array given pool size. |
444 |
< |
* Currently requires size to be a power of two. |
1057 |
> |
* If necessary, compensates for blocker, and blocks. |
1058 |
|
*/ |
1059 |
< |
private static int arraySizeFor(int poolSize) { |
1060 |
< |
return (poolSize <= 1) ? 1 : |
1061 |
< |
(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1))); |
1059 |
> |
private void awaitBlocker(ManagedBlocker blocker) |
1060 |
> |
throws InterruptedException { |
1061 |
> |
while (!blocker.isReleasable()) { |
1062 |
> |
if (tryPreBlock()) { |
1063 |
> |
try { |
1064 |
> |
do {} while (!blocker.isReleasable() && !blocker.block()); |
1065 |
> |
} finally { |
1066 |
> |
postBlock(); |
1067 |
> |
} |
1068 |
> |
break; |
1069 |
> |
} |
1070 |
> |
} |
1071 |
|
} |
1072 |
|
|
1073 |
+ |
// Creating, registering and deregistring workers |
1074 |
+ |
|
1075 |
|
/** |
1076 |
< |
* Creates or resizes array if necessary to hold newLength. |
1077 |
< |
* Call only under exclusion. |
454 |
< |
* |
455 |
< |
* @return the array |
1076 |
> |
* Tries to create and start a worker; minimally rolls back counts |
1077 |
> |
* on failure. |
1078 |
|
*/ |
1079 |
< |
private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) { |
1080 |
< |
ForkJoinWorkerThread[] ws = workers; |
1081 |
< |
if (ws == null) |
1082 |
< |
return workers = new ForkJoinWorkerThread[arraySizeFor(newLength)]; |
1083 |
< |
else if (newLength > ws.length) |
1084 |
< |
return workers = Arrays.copyOf(ws, arraySizeFor(newLength)); |
1079 |
> |
private void addWorker() { |
1080 |
> |
Throwable ex = null; |
1081 |
> |
ForkJoinWorkerThread t = null; |
1082 |
> |
try { |
1083 |
> |
t = factory.newThread(this); |
1084 |
> |
} catch (Throwable e) { |
1085 |
> |
ex = e; |
1086 |
> |
} |
1087 |
> |
if (t == null) { // null or exceptional factory return |
1088 |
> |
long c; // adjust counts |
1089 |
> |
do {} while (!UNSAFE.compareAndSwapLong |
1090 |
> |
(this, ctlOffset, c = ctl, |
1091 |
> |
(((c - AC_UNIT) & AC_MASK) | |
1092 |
> |
((c - TC_UNIT) & TC_MASK) | |
1093 |
> |
(c & ~(AC_MASK|TC_MASK))))); |
1094 |
> |
// Propagate exception if originating from an external caller |
1095 |
> |
if (!tryTerminate(false) && ex != null && |
1096 |
> |
!(Thread.currentThread() instanceof ForkJoinWorkerThread)) |
1097 |
> |
UNSAFE.throwException(ex); |
1098 |
> |
} |
1099 |
|
else |
1100 |
< |
return ws; |
1100 |
> |
t.start(); |
1101 |
|
} |
1102 |
|
|
1103 |
|
/** |
1104 |
< |
* Tries to shrink workers into smaller array after one or more terminate. |
1104 |
> |
* Callback from ForkJoinWorkerThread constructor to assign a |
1105 |
> |
* public name |
1106 |
|
*/ |
1107 |
< |
private void tryShrinkWorkerArray() { |
1108 |
< |
ForkJoinWorkerThread[] ws = workers; |
1109 |
< |
if (ws != null) { |
1110 |
< |
int len = ws.length; |
1111 |
< |
int last = len - 1; |
475 |
< |
while (last >= 0 && ws[last] == null) |
476 |
< |
--last; |
477 |
< |
int newLength = arraySizeFor(last+1); |
478 |
< |
if (newLength < len) |
479 |
< |
workers = Arrays.copyOf(ws, newLength); |
1107 |
> |
final String nextWorkerName() { |
1108 |
> |
for (int n;;) { |
1109 |
> |
if (UNSAFE.compareAndSwapInt(this, nextWorkerNumberOffset, |
1110 |
> |
n = nextWorkerNumber, ++n)) |
1111 |
> |
return workerNamePrefix + n; |
1112 |
|
} |
1113 |
|
} |
1114 |
|
|
1115 |
|
/** |
1116 |
< |
* Initializes workers if necessary. |
1116 |
> |
* Callback from ForkJoinWorkerThread constructor to |
1117 |
> |
* determine its poolIndex and record in workers array. |
1118 |
> |
* |
1119 |
> |
* @param w the worker |
1120 |
> |
* @return the worker's pool index |
1121 |
|
*/ |
1122 |
< |
final void ensureWorkerInitialization() { |
1123 |
< |
ForkJoinWorkerThread[] ws = workers; |
1124 |
< |
if (ws == null) { |
1125 |
< |
final ReentrantLock lock = this.workerLock; |
1126 |
< |
lock.lock(); |
1127 |
< |
try { |
1128 |
< |
ws = workers; |
1129 |
< |
if (ws == null) { |
1130 |
< |
int ps = parallelism; |
1131 |
< |
ws = ensureWorkerArrayCapacity(ps); |
1132 |
< |
for (int i = 0; i < ps; ++i) { |
1133 |
< |
ForkJoinWorkerThread w = createWorker(i); |
1134 |
< |
if (w != null) { |
1135 |
< |
ws[i] = w; |
1136 |
< |
w.start(); |
1137 |
< |
updateWorkerCount(1); |
1122 |
> |
final int registerWorker(ForkJoinWorkerThread w) { |
1123 |
> |
/* |
1124 |
> |
* In the typical case, a new worker acquires the lock, uses |
1125 |
> |
* next available index and returns quickly. Since we should |
1126 |
> |
* not block callers (ultimately from signalWork or |
1127 |
> |
* tryPreBlock) waiting for the lock needed to do this, we |
1128 |
> |
* instead help release other workers while waiting for the |
1129 |
> |
* lock. |
1130 |
> |
*/ |
1131 |
> |
for (int g;;) { |
1132 |
> |
ForkJoinWorkerThread[] ws; |
1133 |
> |
if (((g = scanGuard) & SG_UNIT) == 0 && |
1134 |
> |
UNSAFE.compareAndSwapInt(this, scanGuardOffset, |
1135 |
> |
g, g | SG_UNIT)) { |
1136 |
> |
int k = nextWorkerIndex; |
1137 |
> |
try { |
1138 |
> |
if ((ws = workers) != null) { // ignore on shutdown |
1139 |
> |
int n = ws.length; |
1140 |
> |
if (k < 0 || k >= n || ws[k] != null) { |
1141 |
> |
for (k = 0; k < n && ws[k] != null; ++k) |
1142 |
> |
; |
1143 |
> |
if (k == n) |
1144 |
> |
ws = workers = Arrays.copyOf(ws, n << 1); |
1145 |
|
} |
1146 |
+ |
ws[k] = w; |
1147 |
+ |
nextWorkerIndex = k + 1; |
1148 |
+ |
int m = g & SMASK; |
1149 |
+ |
g = (k > m) ? ((m << 1) + 1) & SMASK : g + (SG_UNIT<<1); |
1150 |
+ |
} |
1151 |
+ |
} finally { |
1152 |
+ |
scanGuard = g; |
1153 |
+ |
} |
1154 |
+ |
return k; |
1155 |
+ |
} |
1156 |
+ |
else if ((ws = workers) != null) { // help release others |
1157 |
+ |
for (ForkJoinWorkerThread u : ws) { |
1158 |
+ |
if (u != null && u.queueBase != u.queueTop) { |
1159 |
+ |
if (tryReleaseWaiter()) |
1160 |
+ |
break; |
1161 |
|
} |
1162 |
|
} |
1163 |
+ |
} |
1164 |
+ |
} |
1165 |
+ |
} |
1166 |
+ |
|
1167 |
+ |
/** |
1168 |
+ |
* Final callback from terminating worker. Removes record of |
1169 |
+ |
* worker from array, and adjusts counts. If pool is shutting |
1170 |
+ |
* down, tries to complete termination. |
1171 |
+ |
* |
1172 |
+ |
* @param w the worker |
1173 |
+ |
*/ |
1174 |
+ |
final void deregisterWorker(ForkJoinWorkerThread w, Throwable ex) { |
1175 |
+ |
int idx = w.poolIndex; |
1176 |
+ |
int sc = w.stealCount; |
1177 |
+ |
int steps = 0; |
1178 |
+ |
// Remove from array, adjust worker counts and collect steal count. |
1179 |
+ |
// We can intermix failed removes or adjusts with steal updates |
1180 |
+ |
do { |
1181 |
+ |
long s, c; |
1182 |
+ |
int g; |
1183 |
+ |
if (steps == 0 && ((g = scanGuard) & SG_UNIT) == 0 && |
1184 |
+ |
UNSAFE.compareAndSwapInt(this, scanGuardOffset, |
1185 |
+ |
g, g |= SG_UNIT)) { |
1186 |
+ |
ForkJoinWorkerThread[] ws = workers; |
1187 |
+ |
if (ws != null && idx >= 0 && |
1188 |
+ |
idx < ws.length && ws[idx] == w) |
1189 |
+ |
ws[idx] = null; // verify |
1190 |
+ |
nextWorkerIndex = idx; |
1191 |
+ |
scanGuard = g + SG_UNIT; |
1192 |
+ |
steps = 1; |
1193 |
+ |
} |
1194 |
+ |
if (steps == 1 && |
1195 |
+ |
UNSAFE.compareAndSwapLong(this, ctlOffset, c = ctl, |
1196 |
+ |
(((c - AC_UNIT) & AC_MASK) | |
1197 |
+ |
((c - TC_UNIT) & TC_MASK) | |
1198 |
+ |
(c & ~(AC_MASK|TC_MASK))))) |
1199 |
+ |
steps = 2; |
1200 |
+ |
if (sc != 0 && |
1201 |
+ |
UNSAFE.compareAndSwapLong(this, stealCountOffset, |
1202 |
+ |
s = stealCount, s + sc)) |
1203 |
+ |
sc = 0; |
1204 |
+ |
} while (steps != 2 || sc != 0); |
1205 |
+ |
if (!tryTerminate(false)) { |
1206 |
+ |
if (ex != null) // possibly replace if died abnormally |
1207 |
+ |
signalWork(); |
1208 |
+ |
else |
1209 |
+ |
tryReleaseWaiter(); |
1210 |
+ |
} |
1211 |
+ |
} |
1212 |
+ |
|
1213 |
+ |
// Shutdown and termination |
1214 |
+ |
|
1215 |
+ |
/** |
1216 |
+ |
* Possibly initiates and/or completes termination. |
1217 |
+ |
* |
1218 |
+ |
* @param now if true, unconditionally terminate, else only |
1219 |
+ |
* if shutdown and empty queue and no active workers |
1220 |
+ |
* @return true if now terminating or terminated |
1221 |
+ |
*/ |
1222 |
+ |
private boolean tryTerminate(boolean now) { |
1223 |
+ |
long c; |
1224 |
+ |
while (((c = ctl) & STOP_BIT) == 0) { |
1225 |
+ |
if (!now) { |
1226 |
+ |
if ((int)(c >> AC_SHIFT) != -parallelism) |
1227 |
+ |
return false; |
1228 |
+ |
if (!shutdown || blockedCount != 0 || quiescerCount != 0 || |
1229 |
+ |
queueBase != queueTop) { |
1230 |
+ |
if (ctl == c) // staleness check |
1231 |
+ |
return false; |
1232 |
+ |
continue; |
1233 |
+ |
} |
1234 |
+ |
} |
1235 |
+ |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, c | STOP_BIT)) |
1236 |
+ |
startTerminating(); |
1237 |
+ |
} |
1238 |
+ |
if ((short)(c >>> TC_SHIFT) == -parallelism) { // signal when 0 workers |
1239 |
+ |
final ReentrantLock lock = this.submissionLock; |
1240 |
+ |
lock.lock(); |
1241 |
+ |
try { |
1242 |
+ |
termination.signalAll(); |
1243 |
|
} finally { |
1244 |
|
lock.unlock(); |
1245 |
|
} |
1246 |
|
} |
1247 |
+ |
return true; |
1248 |
|
} |
1249 |
|
|
1250 |
|
/** |
1251 |
< |
* Worker creation and startup for threads added via setParallelism. |
1252 |
< |
*/ |
1253 |
< |
private void createAndStartAddedWorkers() { |
1254 |
< |
resumeAllSpares(); // Allow spares to convert to nonspare |
1255 |
< |
int ps = parallelism; |
1256 |
< |
ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps); |
1257 |
< |
int len = ws.length; |
1258 |
< |
// Sweep through slots, to keep lowest indices most populated |
1259 |
< |
int k = 0; |
1260 |
< |
while (k < len) { |
1261 |
< |
if (ws[k] != null) { |
1262 |
< |
++k; |
1263 |
< |
continue; |
1251 |
> |
* Runs up to three passes through workers: (0) Setting |
1252 |
> |
* termination status for each worker, followed by wakeups up to |
1253 |
> |
* queued workers; (1) helping cancel tasks; (2) interrupting |
1254 |
> |
* lagging threads (likely in external tasks, but possibly also |
1255 |
> |
* blocked in joins). Each pass repeats previous steps because of |
1256 |
> |
* potential lagging thread creation. |
1257 |
> |
*/ |
1258 |
> |
private void startTerminating() { |
1259 |
> |
cancelSubmissions(); |
1260 |
> |
for (int pass = 0; pass < 3; ++pass) { |
1261 |
> |
ForkJoinWorkerThread[] ws = workers; |
1262 |
> |
if (ws != null) { |
1263 |
> |
for (ForkJoinWorkerThread w : ws) { |
1264 |
> |
if (w != null) { |
1265 |
> |
w.terminate = true; |
1266 |
> |
if (pass > 0) { |
1267 |
> |
w.cancelTasks(); |
1268 |
> |
if (pass > 1 && !w.isInterrupted()) { |
1269 |
> |
try { |
1270 |
> |
w.interrupt(); |
1271 |
> |
} catch (SecurityException ignore) { |
1272 |
> |
} |
1273 |
> |
} |
1274 |
> |
} |
1275 |
> |
} |
1276 |
> |
} |
1277 |
> |
terminateWaiters(); |
1278 |
|
} |
1279 |
< |
int s = workerCounts; |
1280 |
< |
int tc = totalCountOf(s); |
1281 |
< |
int rc = runningCountOf(s); |
1282 |
< |
if (rc >= ps || tc >= ps) |
1283 |
< |
break; |
1284 |
< |
if (casWorkerCounts (s, workerCountsFor(tc+1, rc+1))) { |
1285 |
< |
ForkJoinWorkerThread w = createWorker(k); |
1286 |
< |
if (w != null) { |
1287 |
< |
ws[k++] = w; |
1288 |
< |
w.start(); |
1279 |
> |
} |
1280 |
> |
} |
1281 |
> |
|
1282 |
> |
/** |
1283 |
> |
* Polls and cancels all submissions. Called only during termination. |
1284 |
> |
*/ |
1285 |
> |
private void cancelSubmissions() { |
1286 |
> |
while (queueBase != queueTop) { |
1287 |
> |
ForkJoinTask<?> task = pollSubmission(); |
1288 |
> |
if (task != null) { |
1289 |
> |
try { |
1290 |
> |
task.cancel(false); |
1291 |
> |
} catch (Throwable ignore) { |
1292 |
|
} |
1293 |
< |
else { |
1294 |
< |
updateWorkerCount(-1); // back out on failed creation |
1295 |
< |
break; |
1293 |
> |
} |
1294 |
> |
} |
1295 |
> |
} |
1296 |
> |
|
1297 |
> |
/** |
1298 |
> |
* Tries to set the termination status of waiting workers, and |
1299 |
> |
* then wakes them up (after which they will terminate). |
1300 |
> |
*/ |
1301 |
> |
private void terminateWaiters() { |
1302 |
> |
ForkJoinWorkerThread[] ws = workers; |
1303 |
> |
if (ws != null) { |
1304 |
> |
ForkJoinWorkerThread w; long c; int i, e; |
1305 |
> |
int n = ws.length; |
1306 |
> |
while ((i = ~(e = (int)(c = ctl)) & SMASK) < n && |
1307 |
> |
(w = ws[i]) != null && w.eventCount == (e & E_MASK)) { |
1308 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, |
1309 |
> |
(long)(w.nextWait & E_MASK) | |
1310 |
> |
((c + AC_UNIT) & AC_MASK) | |
1311 |
> |
(c & (TC_MASK|STOP_BIT)))) { |
1312 |
> |
w.terminate = true; |
1313 |
> |
w.eventCount = e + EC_UNIT; |
1314 |
> |
if (w.parked) |
1315 |
> |
UNSAFE.unpark(w); |
1316 |
|
} |
1317 |
|
} |
1318 |
|
} |
1319 |
|
} |
1320 |
|
|
1321 |
< |
// Execution methods |
1321 |
> |
// misc ForkJoinWorkerThread support |
1322 |
|
|
1323 |
|
/** |
1324 |
< |
* Common code for execute, invoke and submit |
1324 |
> |
* Increment or decrement quiescerCount. Needed only to prevent |
1325 |
> |
* triggering shutdown if a worker is transiently inactive while |
1326 |
> |
* checking quiescence. |
1327 |
> |
* |
1328 |
> |
* @param delta 1 for increment, -1 for decrement |
1329 |
|
*/ |
1330 |
< |
private <T> void doSubmit(ForkJoinTask<T> task) { |
1331 |
< |
if (task == null) |
1330 |
> |
final void addQuiescerCount(int delta) { |
1331 |
> |
int c; |
1332 |
> |
do {} while (!UNSAFE.compareAndSwapInt(this, quiescerCountOffset, |
1333 |
> |
c = quiescerCount, c + delta)); |
1334 |
> |
} |
1335 |
> |
|
1336 |
> |
/** |
1337 |
> |
* Directly increment or decrement active count without |
1338 |
> |
* queuing. This method is used to transiently assert inactivation |
1339 |
> |
* while checking quiescence. |
1340 |
> |
* |
1341 |
> |
* @param delta 1 for increment, -1 for decrement |
1342 |
> |
*/ |
1343 |
> |
final void addActiveCount(int delta) { |
1344 |
> |
long d = delta < 0 ? -AC_UNIT : AC_UNIT; |
1345 |
> |
long c; |
1346 |
> |
do {} while (!UNSAFE.compareAndSwapLong(this, ctlOffset, c = ctl, |
1347 |
> |
((c + d) & AC_MASK) | |
1348 |
> |
(c & ~AC_MASK))); |
1349 |
> |
} |
1350 |
> |
|
1351 |
> |
/** |
1352 |
> |
* Returns the approximate (non-atomic) number of idle threads per |
1353 |
> |
* active thread. |
1354 |
> |
*/ |
1355 |
> |
final int idlePerActive() { |
1356 |
> |
// Approximate at powers of two for small values, saturate past 4 |
1357 |
> |
int p = parallelism; |
1358 |
> |
int a = p + (int)(ctl >> AC_SHIFT); |
1359 |
> |
return (a > (p >>>= 1) ? 0 : |
1360 |
> |
a > (p >>>= 1) ? 1 : |
1361 |
> |
a > (p >>>= 1) ? 2 : |
1362 |
> |
a > (p >>>= 1) ? 4 : |
1363 |
> |
8); |
1364 |
> |
} |
1365 |
> |
|
1366 |
> |
// Exported methods |
1367 |
> |
|
1368 |
> |
// Constructors |
1369 |
> |
|
1370 |
> |
/** |
1371 |
> |
* Creates a {@code ForkJoinPool} with parallelism equal to {@link |
1372 |
> |
* java.lang.Runtime#availableProcessors}, using the {@linkplain |
1373 |
> |
* #defaultForkJoinWorkerThreadFactory default thread factory}, |
1374 |
> |
* no UncaughtExceptionHandler, and non-async LIFO processing mode. |
1375 |
> |
* |
1376 |
> |
* @throws SecurityException if a security manager exists and |
1377 |
> |
* the caller is not permitted to modify threads |
1378 |
> |
* because it does not hold {@link |
1379 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1380 |
> |
*/ |
1381 |
> |
public ForkJoinPool() { |
1382 |
> |
this(Runtime.getRuntime().availableProcessors(), |
1383 |
> |
defaultForkJoinWorkerThreadFactory, null, false); |
1384 |
> |
} |
1385 |
> |
|
1386 |
> |
/** |
1387 |
> |
* Creates a {@code ForkJoinPool} with the indicated parallelism |
1388 |
> |
* level, the {@linkplain |
1389 |
> |
* #defaultForkJoinWorkerThreadFactory default thread factory}, |
1390 |
> |
* no UncaughtExceptionHandler, and non-async LIFO processing mode. |
1391 |
> |
* |
1392 |
> |
* @param parallelism the parallelism level |
1393 |
> |
* @throws IllegalArgumentException if parallelism less than or |
1394 |
> |
* equal to zero, or greater than implementation limit |
1395 |
> |
* @throws SecurityException if a security manager exists and |
1396 |
> |
* the caller is not permitted to modify threads |
1397 |
> |
* because it does not hold {@link |
1398 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1399 |
> |
*/ |
1400 |
> |
public ForkJoinPool(int parallelism) { |
1401 |
> |
this(parallelism, defaultForkJoinWorkerThreadFactory, null, false); |
1402 |
> |
} |
1403 |
> |
|
1404 |
> |
/** |
1405 |
> |
* Creates a {@code ForkJoinPool} with the given parameters. |
1406 |
> |
* |
1407 |
> |
* @param parallelism the parallelism level. For default value, |
1408 |
> |
* use {@link java.lang.Runtime#availableProcessors}. |
1409 |
> |
* @param factory the factory for creating new threads. For default value, |
1410 |
> |
* use {@link #defaultForkJoinWorkerThreadFactory}. |
1411 |
> |
* @param handler the handler for internal worker threads that |
1412 |
> |
* terminate due to unrecoverable errors encountered while executing |
1413 |
> |
* tasks. For default value, use {@code null}. |
1414 |
> |
* @param asyncMode if true, |
1415 |
> |
* establishes local first-in-first-out scheduling mode for forked |
1416 |
> |
* tasks that are never joined. This mode may be more appropriate |
1417 |
> |
* than default locally stack-based mode in applications in which |
1418 |
> |
* worker threads only process event-style asynchronous tasks. |
1419 |
> |
* For default value, use {@code false}. |
1420 |
> |
* @throws IllegalArgumentException if parallelism less than or |
1421 |
> |
* equal to zero, or greater than implementation limit |
1422 |
> |
* @throws NullPointerException if the factory is null |
1423 |
> |
* @throws SecurityException if a security manager exists and |
1424 |
> |
* the caller is not permitted to modify threads |
1425 |
> |
* because it does not hold {@link |
1426 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1427 |
> |
*/ |
1428 |
> |
public ForkJoinPool(int parallelism, |
1429 |
> |
ForkJoinWorkerThreadFactory factory, |
1430 |
> |
Thread.UncaughtExceptionHandler handler, |
1431 |
> |
boolean asyncMode) { |
1432 |
> |
checkPermission(); |
1433 |
> |
if (factory == null) |
1434 |
|
throw new NullPointerException(); |
1435 |
< |
if (isShutdown()) |
1436 |
< |
throw new RejectedExecutionException(); |
1437 |
< |
if (workers == null) |
1438 |
< |
ensureWorkerInitialization(); |
1439 |
< |
submissionQueue.offer(task); |
1440 |
< |
signalIdleWorkers(); |
1435 |
> |
if (parallelism <= 0 || parallelism > MAX_ID) |
1436 |
> |
throw new IllegalArgumentException(); |
1437 |
> |
this.parallelism = parallelism; |
1438 |
> |
this.factory = factory; |
1439 |
> |
this.ueh = handler; |
1440 |
> |
this.locallyFifo = asyncMode; |
1441 |
> |
long np = (long)(-parallelism); // offset ctl counts |
1442 |
> |
this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK); |
1443 |
> |
this.submissionQueue = new ForkJoinTask<?>[INITIAL_QUEUE_CAPACITY]; |
1444 |
> |
// initialize workers array with room for 2*parallelism if possible |
1445 |
> |
int n = parallelism << 1; |
1446 |
> |
if (n >= MAX_ID) |
1447 |
> |
n = MAX_ID; |
1448 |
> |
else { // See Hackers Delight, sec 3.2, where n < (1 << 16) |
1449 |
> |
n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; |
1450 |
> |
} |
1451 |
> |
workers = new ForkJoinWorkerThread[n + 1]; |
1452 |
> |
this.submissionLock = new ReentrantLock(); |
1453 |
> |
this.termination = submissionLock.newCondition(); |
1454 |
> |
StringBuilder sb = new StringBuilder("ForkJoinPool-"); |
1455 |
> |
sb.append(poolNumberGenerator.incrementAndGet()); |
1456 |
> |
sb.append("-worker-"); |
1457 |
> |
this.workerNamePrefix = sb.toString(); |
1458 |
|
} |
1459 |
|
|
1460 |
+ |
// Execution methods |
1461 |
+ |
|
1462 |
|
/** |
1463 |
|
* Performs the given task, returning its result upon completion. |
1464 |
+ |
* If the computation encounters an unchecked Exception or Error, |
1465 |
+ |
* it is rethrown as the outcome of this invocation. Rethrown |
1466 |
+ |
* exceptions behave in the same way as regular exceptions, but, |
1467 |
+ |
* when possible, contain stack traces (as displayed for example |
1468 |
+ |
* using {@code ex.printStackTrace()}) of both the current thread |
1469 |
+ |
* as well as the thread actually encountering the exception; |
1470 |
+ |
* minimally only the latter. |
1471 |
|
* |
1472 |
|
* @param task the task |
1473 |
|
* @return the task's result |
1474 |
< |
* @throws NullPointerException if task is null |
1475 |
< |
* @throws RejectedExecutionException if pool is shut down |
1474 |
> |
* @throws NullPointerException if the task is null |
1475 |
> |
* @throws RejectedExecutionException if the task cannot be |
1476 |
> |
* scheduled for execution |
1477 |
|
*/ |
1478 |
|
public <T> T invoke(ForkJoinTask<T> task) { |
1479 |
< |
doSubmit(task); |
1480 |
< |
return task.join(); |
1479 |
> |
Thread t = Thread.currentThread(); |
1480 |
> |
if (task == null) |
1481 |
> |
throw new NullPointerException(); |
1482 |
> |
if (shutdown) |
1483 |
> |
throw new RejectedExecutionException(); |
1484 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
1485 |
> |
((ForkJoinWorkerThread)t).pool == this) |
1486 |
> |
return task.invoke(); // bypass submit if in same pool |
1487 |
> |
else { |
1488 |
> |
addSubmission(task); |
1489 |
> |
return task.join(); |
1490 |
> |
} |
1491 |
> |
} |
1492 |
> |
|
1493 |
> |
/** |
1494 |
> |
* Unless terminating, forks task if within an ongoing FJ |
1495 |
> |
* computation in the current pool, else submits as external task. |
1496 |
> |
*/ |
1497 |
> |
private <T> void forkOrSubmit(ForkJoinTask<T> task) { |
1498 |
> |
ForkJoinWorkerThread w; |
1499 |
> |
Thread t = Thread.currentThread(); |
1500 |
> |
if (shutdown) |
1501 |
> |
throw new RejectedExecutionException(); |
1502 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
1503 |
> |
(w = (ForkJoinWorkerThread)t).pool == this) |
1504 |
> |
w.pushTask(task); |
1505 |
> |
else |
1506 |
> |
addSubmission(task); |
1507 |
|
} |
1508 |
|
|
1509 |
|
/** |
1510 |
|
* Arranges for (asynchronous) execution of the given task. |
1511 |
|
* |
1512 |
|
* @param task the task |
1513 |
< |
* @throws NullPointerException if task is null |
1514 |
< |
* @throws RejectedExecutionException if pool is shut down |
1513 |
> |
* @throws NullPointerException if the task is null |
1514 |
> |
* @throws RejectedExecutionException if the task cannot be |
1515 |
> |
* scheduled for execution |
1516 |
|
*/ |
1517 |
< |
public <T> void execute(ForkJoinTask<T> task) { |
1518 |
< |
doSubmit(task); |
1517 |
> |
public void execute(ForkJoinTask<?> task) { |
1518 |
> |
if (task == null) |
1519 |
> |
throw new NullPointerException(); |
1520 |
> |
forkOrSubmit(task); |
1521 |
|
} |
1522 |
|
|
1523 |
|
// AbstractExecutorService methods |
1524 |
|
|
1525 |
+ |
/** |
1526 |
+ |
* @throws NullPointerException if the task is null |
1527 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1528 |
+ |
* scheduled for execution |
1529 |
+ |
*/ |
1530 |
|
public void execute(Runnable task) { |
1531 |
+ |
if (task == null) |
1532 |
+ |
throw new NullPointerException(); |
1533 |
|
ForkJoinTask<?> job; |
1534 |
< |
if (task instanceof AdaptedCallable) // avoid re-wrap |
1535 |
< |
job = (AdaptedCallable<?>)task; |
591 |
< |
else if (task instanceof AdaptedRunnable) |
592 |
< |
job = (AdaptedRunnable<?>)task; |
593 |
< |
else |
594 |
< |
job = new AdaptedRunnable<Void>(task, null); |
595 |
< |
doSubmit(job); |
596 |
< |
} |
597 |
< |
|
598 |
< |
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
599 |
< |
ForkJoinTask<T> job = new AdaptedCallable<T>(task); |
600 |
< |
doSubmit(job); |
601 |
< |
return job; |
602 |
< |
} |
603 |
< |
|
604 |
< |
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
605 |
< |
ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result); |
606 |
< |
doSubmit(job); |
607 |
< |
return job; |
608 |
< |
} |
609 |
< |
|
610 |
< |
public ForkJoinTask<?> submit(Runnable task) { |
611 |
< |
ForkJoinTask<?> job; |
612 |
< |
if (task instanceof AdaptedCallable) // avoid re-wrap |
613 |
< |
job = (AdaptedCallable<?>)task; |
614 |
< |
else if (task instanceof AdaptedRunnable) |
615 |
< |
job = (AdaptedRunnable<?>)task; |
1534 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
1535 |
> |
job = (ForkJoinTask<?>) task; |
1536 |
|
else |
1537 |
< |
job = new AdaptedRunnable<Void>(task, null); |
1538 |
< |
doSubmit(job); |
619 |
< |
return job; |
1537 |
> |
job = ForkJoinTask.adapt(task, null); |
1538 |
> |
forkOrSubmit(job); |
1539 |
|
} |
1540 |
|
|
1541 |
|
/** |
1543 |
|
* |
1544 |
|
* @param task the task to submit |
1545 |
|
* @return the task |
1546 |
+ |
* @throws NullPointerException if the task is null |
1547 |
|
* @throws RejectedExecutionException if the task cannot be |
1548 |
|
* scheduled for execution |
629 |
– |
* @throws NullPointerException if the task is null |
1549 |
|
*/ |
1550 |
|
public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) { |
1551 |
< |
doSubmit(task); |
1551 |
> |
if (task == null) |
1552 |
> |
throw new NullPointerException(); |
1553 |
> |
forkOrSubmit(task); |
1554 |
|
return task; |
1555 |
|
} |
1556 |
|
|
1557 |
|
/** |
1558 |
< |
* Adaptor for Runnables. This implements RunnableFuture |
1559 |
< |
* to be compliant with AbstractExecutorService constraints. |
1558 |
> |
* @throws NullPointerException if the task is null |
1559 |
> |
* @throws RejectedExecutionException if the task cannot be |
1560 |
> |
* scheduled for execution |
1561 |
|
*/ |
1562 |
< |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1563 |
< |
implements RunnableFuture<T> { |
1564 |
< |
final Runnable runnable; |
1565 |
< |
final T resultOnCompletion; |
1566 |
< |
T result; |
1567 |
< |
AdaptedRunnable(Runnable runnable, T result) { |
646 |
< |
if (runnable == null) throw new NullPointerException(); |
647 |
< |
this.runnable = runnable; |
648 |
< |
this.resultOnCompletion = result; |
649 |
< |
} |
650 |
< |
public T getRawResult() { return result; } |
651 |
< |
public void setRawResult(T v) { result = v; } |
652 |
< |
public boolean exec() { |
653 |
< |
runnable.run(); |
654 |
< |
result = resultOnCompletion; |
655 |
< |
return true; |
656 |
< |
} |
657 |
< |
public void run() { invoke(); } |
658 |
< |
private static final long serialVersionUID = 5232453952276885070L; |
1562 |
> |
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
1563 |
> |
if (task == null) |
1564 |
> |
throw new NullPointerException(); |
1565 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task); |
1566 |
> |
forkOrSubmit(job); |
1567 |
> |
return job; |
1568 |
|
} |
1569 |
|
|
1570 |
|
/** |
1571 |
< |
* Adaptor for Callables |
1572 |
< |
*/ |
1573 |
< |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1574 |
< |
implements RunnableFuture<T> { |
1575 |
< |
final Callable<T> callable; |
1576 |
< |
T result; |
1577 |
< |
AdaptedCallable(Callable<T> callable) { |
1578 |
< |
if (callable == null) throw new NullPointerException(); |
1579 |
< |
this.callable = callable; |
1580 |
< |
} |
672 |
< |
public T getRawResult() { return result; } |
673 |
< |
public void setRawResult(T v) { result = v; } |
674 |
< |
public boolean exec() { |
675 |
< |
try { |
676 |
< |
result = callable.call(); |
677 |
< |
return true; |
678 |
< |
} catch (Error err) { |
679 |
< |
throw err; |
680 |
< |
} catch (RuntimeException rex) { |
681 |
< |
throw rex; |
682 |
< |
} catch (Exception ex) { |
683 |
< |
throw new RuntimeException(ex); |
684 |
< |
} |
685 |
< |
} |
686 |
< |
public void run() { invoke(); } |
687 |
< |
private static final long serialVersionUID = 2838392045355241008L; |
1571 |
> |
* @throws NullPointerException if the task is null |
1572 |
> |
* @throws RejectedExecutionException if the task cannot be |
1573 |
> |
* scheduled for execution |
1574 |
> |
*/ |
1575 |
> |
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
1576 |
> |
if (task == null) |
1577 |
> |
throw new NullPointerException(); |
1578 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task, result); |
1579 |
> |
forkOrSubmit(job); |
1580 |
> |
return job; |
1581 |
|
} |
1582 |
|
|
1583 |
+ |
/** |
1584 |
+ |
* @throws NullPointerException if the task is null |
1585 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1586 |
+ |
* scheduled for execution |
1587 |
+ |
*/ |
1588 |
+ |
public ForkJoinTask<?> submit(Runnable task) { |
1589 |
+ |
if (task == null) |
1590 |
+ |
throw new NullPointerException(); |
1591 |
+ |
ForkJoinTask<?> job; |
1592 |
+ |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
1593 |
+ |
job = (ForkJoinTask<?>) task; |
1594 |
+ |
else |
1595 |
+ |
job = ForkJoinTask.adapt(task, null); |
1596 |
+ |
forkOrSubmit(job); |
1597 |
+ |
return job; |
1598 |
+ |
} |
1599 |
+ |
|
1600 |
+ |
/** |
1601 |
+ |
* @throws NullPointerException {@inheritDoc} |
1602 |
+ |
* @throws RejectedExecutionException {@inheritDoc} |
1603 |
+ |
*/ |
1604 |
|
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { |
1605 |
|
ArrayList<ForkJoinTask<T>> forkJoinTasks = |
1606 |
|
new ArrayList<ForkJoinTask<T>>(tasks.size()); |
1607 |
|
for (Callable<T> task : tasks) |
1608 |
< |
forkJoinTasks.add(new AdaptedCallable<T>(task)); |
1608 |
> |
forkJoinTasks.add(ForkJoinTask.adapt(task)); |
1609 |
|
invoke(new InvokeAll<T>(forkJoinTasks)); |
1610 |
|
|
1611 |
|
@SuppressWarnings({"unchecked", "rawtypes"}) |
1612 |
< |
List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks; |
1612 |
> |
List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks; |
1613 |
|
return futures; |
1614 |
|
} |
1615 |
|
|
1623 |
|
private static final long serialVersionUID = -7914297376763021607L; |
1624 |
|
} |
1625 |
|
|
712 |
– |
// Configuration and status settings and queries |
713 |
– |
|
1626 |
|
/** |
1627 |
|
* Returns the factory used for constructing new workers. |
1628 |
|
* |
1636 |
|
* Returns the handler for internal worker threads that terminate |
1637 |
|
* due to unrecoverable errors encountered while executing tasks. |
1638 |
|
* |
1639 |
< |
* @return the handler, or null if none |
1639 |
> |
* @return the handler, or {@code null} if none |
1640 |
|
*/ |
1641 |
|
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
1642 |
< |
Thread.UncaughtExceptionHandler h; |
731 |
< |
final ReentrantLock lock = this.workerLock; |
732 |
< |
lock.lock(); |
733 |
< |
try { |
734 |
< |
h = ueh; |
735 |
< |
} finally { |
736 |
< |
lock.unlock(); |
737 |
< |
} |
738 |
< |
return h; |
1642 |
> |
return ueh; |
1643 |
|
} |
1644 |
|
|
1645 |
|
/** |
1646 |
< |
* Sets the handler for internal worker threads that terminate due |
743 |
< |
* to unrecoverable errors encountered while executing tasks. |
744 |
< |
* Unless set, the current default or ThreadGroup handler is used |
745 |
< |
* as handler. |
1646 |
> |
* Returns the targeted parallelism level of this pool. |
1647 |
|
* |
1648 |
< |
* @param h the new handler |
748 |
< |
* @return the old handler, or null if none |
749 |
< |
* @throws SecurityException if a security manager exists and |
750 |
< |
* the caller is not permitted to modify threads |
751 |
< |
* because it does not hold {@link |
752 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
753 |
< |
*/ |
754 |
< |
public Thread.UncaughtExceptionHandler |
755 |
< |
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) { |
756 |
< |
checkPermission(); |
757 |
< |
Thread.UncaughtExceptionHandler old = null; |
758 |
< |
final ReentrantLock lock = this.workerLock; |
759 |
< |
lock.lock(); |
760 |
< |
try { |
761 |
< |
old = ueh; |
762 |
< |
ueh = h; |
763 |
< |
ForkJoinWorkerThread[] ws = workers; |
764 |
< |
if (ws != null) { |
765 |
< |
for (int i = 0; i < ws.length; ++i) { |
766 |
< |
ForkJoinWorkerThread w = ws[i]; |
767 |
< |
if (w != null) |
768 |
< |
w.setUncaughtExceptionHandler(h); |
769 |
< |
} |
770 |
< |
} |
771 |
< |
} finally { |
772 |
< |
lock.unlock(); |
773 |
< |
} |
774 |
< |
return old; |
775 |
< |
} |
776 |
< |
|
777 |
< |
|
778 |
< |
/** |
779 |
< |
* Sets the target parallelism level of this pool. |
780 |
< |
* |
781 |
< |
* @param parallelism the target parallelism |
782 |
< |
* @throws IllegalArgumentException if parallelism less than or |
783 |
< |
* equal to zero or greater than maximum size bounds |
784 |
< |
* @throws SecurityException if a security manager exists and |
785 |
< |
* the caller is not permitted to modify threads |
786 |
< |
* because it does not hold {@link |
787 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
788 |
< |
*/ |
789 |
< |
public void setParallelism(int parallelism) { |
790 |
< |
checkPermission(); |
791 |
< |
if (parallelism <= 0 || parallelism > maxPoolSize) |
792 |
< |
throw new IllegalArgumentException(); |
793 |
< |
final ReentrantLock lock = this.workerLock; |
794 |
< |
lock.lock(); |
795 |
< |
try { |
796 |
< |
if (!isTerminating()) { |
797 |
< |
int p = this.parallelism; |
798 |
< |
this.parallelism = parallelism; |
799 |
< |
if (parallelism > p) |
800 |
< |
createAndStartAddedWorkers(); |
801 |
< |
else |
802 |
< |
trimSpares(); |
803 |
< |
} |
804 |
< |
} finally { |
805 |
< |
lock.unlock(); |
806 |
< |
} |
807 |
< |
signalIdleWorkers(); |
808 |
< |
} |
809 |
< |
|
810 |
< |
/** |
811 |
< |
* Returns the targeted number of worker threads in this pool. |
812 |
< |
* |
813 |
< |
* @return the targeted number of worker threads in this pool |
1648 |
> |
* @return the targeted parallelism level of this pool |
1649 |
|
*/ |
1650 |
|
public int getParallelism() { |
1651 |
|
return parallelism; |
1653 |
|
|
1654 |
|
/** |
1655 |
|
* Returns the number of worker threads that have started but not |
1656 |
< |
* yet terminated. This result returned by this method may differ |
1657 |
< |
* from {@code getParallelism} when threads are created to |
1656 |
> |
* yet terminated. The result returned by this method may differ |
1657 |
> |
* from {@link #getParallelism} when threads are created to |
1658 |
|
* maintain parallelism when others are cooperatively blocked. |
1659 |
|
* |
1660 |
|
* @return the number of worker threads |
1661 |
|
*/ |
1662 |
|
public int getPoolSize() { |
1663 |
< |
return totalCountOf(workerCounts); |
829 |
< |
} |
830 |
< |
|
831 |
< |
/** |
832 |
< |
* Returns the maximum number of threads allowed to exist in the |
833 |
< |
* pool, even if there are insufficient unblocked running threads. |
834 |
< |
* |
835 |
< |
* @return the maximum |
836 |
< |
*/ |
837 |
< |
public int getMaximumPoolSize() { |
838 |
< |
return maxPoolSize; |
839 |
< |
} |
840 |
< |
|
841 |
< |
/** |
842 |
< |
* Sets the maximum number of threads allowed to exist in the |
843 |
< |
* pool, even if there are insufficient unblocked running threads. |
844 |
< |
* Setting this value has no effect on current pool size. It |
845 |
< |
* controls construction of new threads. |
846 |
< |
* |
847 |
< |
* @throws IllegalArgumentException if negative or greater then |
848 |
< |
* internal implementation limit |
849 |
< |
*/ |
850 |
< |
public void setMaximumPoolSize(int newMax) { |
851 |
< |
if (newMax < 0 || newMax > MAX_THREADS) |
852 |
< |
throw new IllegalArgumentException(); |
853 |
< |
maxPoolSize = newMax; |
854 |
< |
} |
855 |
< |
|
856 |
< |
|
857 |
< |
/** |
858 |
< |
* Returns true if this pool dynamically maintains its target |
859 |
< |
* parallelism level. If false, new threads are added only to |
860 |
< |
* avoid possible starvation. |
861 |
< |
* This setting is by default true. |
862 |
< |
* |
863 |
< |
* @return true if maintains parallelism |
864 |
< |
*/ |
865 |
< |
public boolean getMaintainsParallelism() { |
866 |
< |
return maintainsParallelism; |
867 |
< |
} |
868 |
< |
|
869 |
< |
/** |
870 |
< |
* Sets whether this pool dynamically maintains its target |
871 |
< |
* parallelism level. If false, new threads are added only to |
872 |
< |
* avoid possible starvation. |
873 |
< |
* |
874 |
< |
* @param enable true to maintains parallelism |
875 |
< |
*/ |
876 |
< |
public void setMaintainsParallelism(boolean enable) { |
877 |
< |
maintainsParallelism = enable; |
878 |
< |
} |
879 |
< |
|
880 |
< |
/** |
881 |
< |
* Establishes local first-in-first-out scheduling mode for forked |
882 |
< |
* tasks that are never joined. This mode may be more appropriate |
883 |
< |
* than default locally stack-based mode in applications in which |
884 |
< |
* worker threads only process asynchronous tasks. This method is |
885 |
< |
* designed to be invoked only when pool is quiescent, and |
886 |
< |
* typically only before any tasks are submitted. The effects of |
887 |
< |
* invocations at other times may be unpredictable. |
888 |
< |
* |
889 |
< |
* @param async if true, use locally FIFO scheduling |
890 |
< |
* @return the previous mode |
891 |
< |
*/ |
892 |
< |
public boolean setAsyncMode(boolean async) { |
893 |
< |
boolean oldMode = locallyFifo; |
894 |
< |
locallyFifo = async; |
895 |
< |
ForkJoinWorkerThread[] ws = workers; |
896 |
< |
if (ws != null) { |
897 |
< |
for (int i = 0; i < ws.length; ++i) { |
898 |
< |
ForkJoinWorkerThread t = ws[i]; |
899 |
< |
if (t != null) |
900 |
< |
t.setAsyncMode(async); |
901 |
< |
} |
902 |
< |
} |
903 |
< |
return oldMode; |
1663 |
> |
return parallelism + (short)(ctl >>> TC_SHIFT); |
1664 |
|
} |
1665 |
|
|
1666 |
|
/** |
1667 |
< |
* Returns true if this pool uses local first-in-first-out |
1667 |
> |
* Returns {@code true} if this pool uses local first-in-first-out |
1668 |
|
* scheduling mode for forked tasks that are never joined. |
1669 |
|
* |
1670 |
< |
* @return true if this pool uses async mode |
1670 |
> |
* @return {@code true} if this pool uses async mode |
1671 |
|
*/ |
1672 |
|
public boolean getAsyncMode() { |
1673 |
|
return locallyFifo; |
1676 |
|
/** |
1677 |
|
* Returns an estimate of the number of worker threads that are |
1678 |
|
* not blocked waiting to join tasks or for other managed |
1679 |
< |
* synchronization. |
1679 |
> |
* synchronization. This method may overestimate the |
1680 |
> |
* number of running threads. |
1681 |
|
* |
1682 |
|
* @return the number of worker threads |
1683 |
|
*/ |
1684 |
|
public int getRunningThreadCount() { |
1685 |
< |
return runningCountOf(workerCounts); |
1685 |
> |
int r = parallelism + (int)(ctl >> AC_SHIFT); |
1686 |
> |
return (r <= 0) ? 0 : r; // suppress momentarily negative values |
1687 |
|
} |
1688 |
|
|
1689 |
|
/** |
1694 |
|
* @return the number of active threads |
1695 |
|
*/ |
1696 |
|
public int getActiveThreadCount() { |
1697 |
< |
return activeCountOf(runControl); |
1697 |
> |
int r = parallelism + (int)(ctl >> AC_SHIFT) + blockedCount; |
1698 |
> |
return (r <= 0) ? 0 : r; // suppress momentarily negative values |
1699 |
|
} |
1700 |
|
|
1701 |
|
/** |
1702 |
< |
* Returns an estimate of the number of threads that are currently |
1703 |
< |
* idle waiting for tasks. This method may underestimate the |
1704 |
< |
* number of idle threads. |
1702 |
> |
* Returns {@code true} if all worker threads are currently idle. |
1703 |
> |
* An idle worker is one that cannot obtain a task to execute |
1704 |
> |
* because none are available to steal from other threads, and |
1705 |
> |
* there are no pending submissions to the pool. This method is |
1706 |
> |
* conservative; it might not return {@code true} immediately upon |
1707 |
> |
* idleness of all threads, but will eventually become true if |
1708 |
> |
* threads remain inactive. |
1709 |
|
* |
1710 |
< |
* @return the number of idle threads |
944 |
< |
*/ |
945 |
< |
final int getIdleThreadCount() { |
946 |
< |
int c = runningCountOf(workerCounts) - activeCountOf(runControl); |
947 |
< |
return (c <= 0) ? 0 : c; |
948 |
< |
} |
949 |
< |
|
950 |
< |
/** |
951 |
< |
* Returns true if all worker threads are currently idle. An idle |
952 |
< |
* worker is one that cannot obtain a task to execute because none |
953 |
< |
* are available to steal from other threads, and there are no |
954 |
< |
* pending submissions to the pool. This method is conservative; |
955 |
< |
* it might not return true immediately upon idleness of all |
956 |
< |
* threads, but will eventually become true if threads remain |
957 |
< |
* inactive. |
958 |
< |
* |
959 |
< |
* @return true if all threads are currently idle |
1710 |
> |
* @return {@code true} if all threads are currently idle |
1711 |
|
*/ |
1712 |
|
public boolean isQuiescent() { |
1713 |
< |
return activeCountOf(runControl) == 0; |
1713 |
> |
return parallelism + (int)(ctl >> AC_SHIFT) + blockedCount == 0; |
1714 |
|
} |
1715 |
|
|
1716 |
|
/** |
1725 |
|
* @return the number of steals |
1726 |
|
*/ |
1727 |
|
public long getStealCount() { |
1728 |
< |
return stealCount.get(); |
978 |
< |
} |
979 |
< |
|
980 |
< |
/** |
981 |
< |
* Accumulates steal count from a worker. |
982 |
< |
* Call only when worker known to be idle. |
983 |
< |
*/ |
984 |
< |
private void updateStealCount(ForkJoinWorkerThread w) { |
985 |
< |
int sc = w.getAndClearStealCount(); |
986 |
< |
if (sc != 0) |
987 |
< |
stealCount.addAndGet(sc); |
1728 |
> |
return stealCount; |
1729 |
|
} |
1730 |
|
|
1731 |
|
/** |
1740 |
|
*/ |
1741 |
|
public long getQueuedTaskCount() { |
1742 |
|
long count = 0; |
1743 |
< |
ForkJoinWorkerThread[] ws = workers; |
1744 |
< |
if (ws != null) { |
1745 |
< |
for (int i = 0; i < ws.length; ++i) { |
1746 |
< |
ForkJoinWorkerThread t = ws[i]; |
1747 |
< |
if (t != null) |
1748 |
< |
count += t.getQueueSize(); |
1008 |
< |
} |
1743 |
> |
ForkJoinWorkerThread[] ws; |
1744 |
> |
if ((short)(ctl >>> TC_SHIFT) > -parallelism && |
1745 |
> |
(ws = workers) != null) { |
1746 |
> |
for (ForkJoinWorkerThread w : ws) |
1747 |
> |
if (w != null) |
1748 |
> |
count -= w.queueBase - w.queueTop; // must read base first |
1749 |
|
} |
1750 |
|
return count; |
1751 |
|
} |
1752 |
|
|
1753 |
|
/** |
1754 |
< |
* Returns an estimate of the number tasks submitted to this pool |
1755 |
< |
* that have not yet begun executing. This method takes time |
1756 |
< |
* proportional to the number of submissions. |
1754 |
> |
* Returns an estimate of the number of tasks submitted to this |
1755 |
> |
* pool that have not yet begun executing. This method may take |
1756 |
> |
* time proportional to the number of submissions. |
1757 |
|
* |
1758 |
|
* @return the number of queued submissions |
1759 |
|
*/ |
1760 |
|
public int getQueuedSubmissionCount() { |
1761 |
< |
return submissionQueue.size(); |
1761 |
> |
return -queueBase + queueTop; |
1762 |
|
} |
1763 |
|
|
1764 |
|
/** |
1765 |
< |
* Returns true if there are any tasks submitted to this pool |
1766 |
< |
* that have not yet begun executing. |
1765 |
> |
* Returns {@code true} if there are any tasks submitted to this |
1766 |
> |
* pool that have not yet begun executing. |
1767 |
|
* |
1768 |
|
* @return {@code true} if there are any queued submissions |
1769 |
|
*/ |
1770 |
|
public boolean hasQueuedSubmissions() { |
1771 |
< |
return !submissionQueue.isEmpty(); |
1771 |
> |
return queueBase != queueTop; |
1772 |
|
} |
1773 |
|
|
1774 |
|
/** |
1776 |
|
* available. This method may be useful in extensions to this |
1777 |
|
* class that re-assign work in systems with multiple pools. |
1778 |
|
* |
1779 |
< |
* @return the next submission, or null if none |
1779 |
> |
* @return the next submission, or {@code null} if none |
1780 |
|
*/ |
1781 |
|
protected ForkJoinTask<?> pollSubmission() { |
1782 |
< |
return submissionQueue.poll(); |
1782 |
> |
ForkJoinTask<?> t; ForkJoinTask<?>[] q; int b, i; |
1783 |
> |
while ((b = queueBase) != queueTop && |
1784 |
> |
(q = submissionQueue) != null && |
1785 |
> |
(i = (q.length - 1) & b) >= 0) { |
1786 |
> |
long u = (i << ASHIFT) + ABASE; |
1787 |
> |
if ((t = q[i]) != null && |
1788 |
> |
queueBase == b && |
1789 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
1790 |
> |
queueBase = b + 1; |
1791 |
> |
return t; |
1792 |
> |
} |
1793 |
> |
} |
1794 |
> |
return null; |
1795 |
|
} |
1796 |
|
|
1797 |
|
/** |
1798 |
|
* Removes all available unexecuted submitted and forked tasks |
1799 |
|
* from scheduling queues and adds them to the given collection, |
1800 |
|
* without altering their execution status. These may include |
1801 |
< |
* artificially generated or wrapped tasks. This method is designed |
1802 |
< |
* to be invoked only when the pool is known to be |
1801 |
> |
* artificially generated or wrapped tasks. This method is |
1802 |
> |
* designed to be invoked only when the pool is known to be |
1803 |
|
* quiescent. Invocations at other times may not remove all |
1804 |
|
* tasks. A failure encountered while attempting to add elements |
1805 |
|
* to collection {@code c} may result in elements being in |
1811 |
|
* @param c the collection to transfer elements into |
1812 |
|
* @return the number of elements transferred |
1813 |
|
*/ |
1814 |
< |
protected int drainTasksTo(Collection<ForkJoinTask<?>> c) { |
1815 |
< |
int n = submissionQueue.drainTo(c); |
1816 |
< |
ForkJoinWorkerThread[] ws = workers; |
1817 |
< |
if (ws != null) { |
1818 |
< |
for (int i = 0; i < ws.length; ++i) { |
1819 |
< |
ForkJoinWorkerThread w = ws[i]; |
1820 |
< |
if (w != null) |
1069 |
< |
n += w.drainTasksTo(c); |
1814 |
> |
protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) { |
1815 |
> |
int count = 0; |
1816 |
> |
while (queueBase != queueTop) { |
1817 |
> |
ForkJoinTask<?> t = pollSubmission(); |
1818 |
> |
if (t != null) { |
1819 |
> |
c.add(t); |
1820 |
> |
++count; |
1821 |
|
} |
1822 |
|
} |
1823 |
< |
return n; |
1823 |
> |
ForkJoinWorkerThread[] ws; |
1824 |
> |
if ((short)(ctl >>> TC_SHIFT) > -parallelism && |
1825 |
> |
(ws = workers) != null) { |
1826 |
> |
for (ForkJoinWorkerThread w : ws) |
1827 |
> |
if (w != null) |
1828 |
> |
count += w.drainTasksTo(c); |
1829 |
> |
} |
1830 |
> |
return count; |
1831 |
|
} |
1832 |
|
|
1833 |
|
/** |
1838 |
|
* @return a string identifying this pool, as well as its state |
1839 |
|
*/ |
1840 |
|
public String toString() { |
1083 |
– |
int ps = parallelism; |
1084 |
– |
int wc = workerCounts; |
1085 |
– |
int rc = runControl; |
1841 |
|
long st = getStealCount(); |
1842 |
|
long qt = getQueuedTaskCount(); |
1843 |
|
long qs = getQueuedSubmissionCount(); |
1844 |
+ |
int pc = parallelism; |
1845 |
+ |
long c = ctl; |
1846 |
+ |
int tc = pc + (short)(c >>> TC_SHIFT); |
1847 |
+ |
int rc = pc + (int)(c >> AC_SHIFT); |
1848 |
+ |
if (rc < 0) // ignore transient negative |
1849 |
+ |
rc = 0; |
1850 |
+ |
int ac = rc + blockedCount; |
1851 |
+ |
String level; |
1852 |
+ |
if ((c & STOP_BIT) != 0) |
1853 |
+ |
level = (tc == 0) ? "Terminated" : "Terminating"; |
1854 |
+ |
else |
1855 |
+ |
level = shutdown ? "Shutting down" : "Running"; |
1856 |
|
return super.toString() + |
1857 |
< |
"[" + runStateToString(runStateOf(rc)) + |
1858 |
< |
", parallelism = " + ps + |
1859 |
< |
", size = " + totalCountOf(wc) + |
1860 |
< |
", active = " + activeCountOf(rc) + |
1861 |
< |
", running = " + runningCountOf(wc) + |
1857 |
> |
"[" + level + |
1858 |
> |
", parallelism = " + pc + |
1859 |
> |
", size = " + tc + |
1860 |
> |
", active = " + ac + |
1861 |
> |
", running = " + rc + |
1862 |
|
", steals = " + st + |
1863 |
|
", tasks = " + qt + |
1864 |
|
", submissions = " + qs + |
1865 |
|
"]"; |
1866 |
|
} |
1867 |
|
|
1101 |
– |
private static String runStateToString(int rs) { |
1102 |
– |
switch(rs) { |
1103 |
– |
case RUNNING: return "Running"; |
1104 |
– |
case SHUTDOWN: return "Shutting down"; |
1105 |
– |
case TERMINATING: return "Terminating"; |
1106 |
– |
case TERMINATED: return "Terminated"; |
1107 |
– |
default: throw new Error("Unknown run state"); |
1108 |
– |
} |
1109 |
– |
} |
1110 |
– |
|
1111 |
– |
// lifecycle control |
1112 |
– |
|
1868 |
|
/** |
1869 |
|
* Initiates an orderly shutdown in which previously submitted |
1870 |
|
* tasks are executed, but no new tasks will be accepted. |
1879 |
|
*/ |
1880 |
|
public void shutdown() { |
1881 |
|
checkPermission(); |
1882 |
< |
transitionRunStateTo(SHUTDOWN); |
1883 |
< |
if (canTerminateOnShutdown(runControl)) |
1129 |
< |
terminateOnShutdown(); |
1882 |
> |
shutdown = true; |
1883 |
> |
tryTerminate(false); |
1884 |
|
} |
1885 |
|
|
1886 |
|
/** |
1887 |
< |
* Attempts to stop all actively executing tasks, and cancels all |
1888 |
< |
* waiting tasks. Tasks that are in the process of being |
1889 |
< |
* submitted or executed concurrently during the course of this |
1890 |
< |
* method may or may not be rejected. Unlike some other executors, |
1891 |
< |
* this method cancels rather than collects non-executed tasks |
1892 |
< |
* upon termination, so always returns an empty list. However, you |
1893 |
< |
* can use method {@code drainTasksTo} before invoking this |
1894 |
< |
* method to transfer unexecuted tasks to another collection. |
1887 |
> |
* Attempts to cancel and/or stop all tasks, and reject all |
1888 |
> |
* subsequently submitted tasks. Tasks that are in the process of |
1889 |
> |
* being submitted or executed concurrently during the course of |
1890 |
> |
* this method may or may not be rejected. This method cancels |
1891 |
> |
* both existing and unexecuted tasks, in order to permit |
1892 |
> |
* termination in the presence of task dependencies. So the method |
1893 |
> |
* always returns an empty list (unlike the case for some other |
1894 |
> |
* Executors). |
1895 |
|
* |
1896 |
|
* @return an empty list |
1897 |
|
* @throws SecurityException if a security manager exists and |
1901 |
|
*/ |
1902 |
|
public List<Runnable> shutdownNow() { |
1903 |
|
checkPermission(); |
1904 |
< |
terminate(); |
1904 |
> |
shutdown = true; |
1905 |
> |
tryTerminate(true); |
1906 |
|
return Collections.emptyList(); |
1907 |
|
} |
1908 |
|
|
1912 |
|
* @return {@code true} if all tasks have completed following shut down |
1913 |
|
*/ |
1914 |
|
public boolean isTerminated() { |
1915 |
< |
return runStateOf(runControl) == TERMINATED; |
1915 |
> |
long c = ctl; |
1916 |
> |
return ((c & STOP_BIT) != 0L && |
1917 |
> |
(short)(c >>> TC_SHIFT) == -parallelism); |
1918 |
|
} |
1919 |
|
|
1920 |
|
/** |
1921 |
|
* Returns {@code true} if the process of termination has |
1922 |
< |
* commenced but possibly not yet completed. |
1922 |
> |
* commenced but not yet completed. This method may be useful for |
1923 |
> |
* debugging. A return of {@code true} reported a sufficient |
1924 |
> |
* period after shutdown may indicate that submitted tasks have |
1925 |
> |
* ignored or suppressed interruption, or are waiting for IO, |
1926 |
> |
* causing this executor not to properly terminate. (See the |
1927 |
> |
* advisory notes for class {@link ForkJoinTask} stating that |
1928 |
> |
* tasks should not normally entail blocking operations. But if |
1929 |
> |
* they do, they must abort them on interrupt.) |
1930 |
|
* |
1931 |
< |
* @return {@code true} if terminating |
1931 |
> |
* @return {@code true} if terminating but not yet terminated |
1932 |
|
*/ |
1933 |
|
public boolean isTerminating() { |
1934 |
< |
return runStateOf(runControl) >= TERMINATING; |
1934 |
> |
long c = ctl; |
1935 |
> |
return ((c & STOP_BIT) != 0L && |
1936 |
> |
(short)(c >>> TC_SHIFT) != -parallelism); |
1937 |
> |
} |
1938 |
> |
|
1939 |
> |
/** |
1940 |
> |
* Returns true if terminating or terminated. Used by ForkJoinWorkerThread. |
1941 |
> |
*/ |
1942 |
> |
final boolean isAtLeastTerminating() { |
1943 |
> |
return (ctl & STOP_BIT) != 0L; |
1944 |
|
} |
1945 |
|
|
1946 |
|
/** |
1949 |
|
* @return {@code true} if this pool has been shut down |
1950 |
|
*/ |
1951 |
|
public boolean isShutdown() { |
1952 |
< |
return runStateOf(runControl) >= SHUTDOWN; |
1952 |
> |
return shutdown; |
1953 |
|
} |
1954 |
|
|
1955 |
|
/** |
1966 |
|
public boolean awaitTermination(long timeout, TimeUnit unit) |
1967 |
|
throws InterruptedException { |
1968 |
|
long nanos = unit.toNanos(timeout); |
1969 |
< |
final ReentrantLock lock = this.workerLock; |
1969 |
> |
final ReentrantLock lock = this.submissionLock; |
1970 |
|
lock.lock(); |
1971 |
|
try { |
1972 |
|
for (;;) { |
1981 |
|
} |
1982 |
|
} |
1983 |
|
|
1211 |
– |
// Shutdown and termination support |
1212 |
– |
|
1213 |
– |
/** |
1214 |
– |
* Callback from terminating worker. Nulls out the corresponding |
1215 |
– |
* workers slot, and if terminating, tries to terminate; else |
1216 |
– |
* tries to shrink workers array. |
1217 |
– |
* |
1218 |
– |
* @param w the worker |
1219 |
– |
*/ |
1220 |
– |
final void workerTerminated(ForkJoinWorkerThread w) { |
1221 |
– |
updateStealCount(w); |
1222 |
– |
updateWorkerCount(-1); |
1223 |
– |
final ReentrantLock lock = this.workerLock; |
1224 |
– |
lock.lock(); |
1225 |
– |
try { |
1226 |
– |
ForkJoinWorkerThread[] ws = workers; |
1227 |
– |
if (ws != null) { |
1228 |
– |
int idx = w.poolIndex; |
1229 |
– |
if (idx >= 0 && idx < ws.length && ws[idx] == w) |
1230 |
– |
ws[idx] = null; |
1231 |
– |
if (totalCountOf(workerCounts) == 0) { |
1232 |
– |
terminate(); // no-op if already terminating |
1233 |
– |
transitionRunStateTo(TERMINATED); |
1234 |
– |
termination.signalAll(); |
1235 |
– |
} |
1236 |
– |
else if (!isTerminating()) { |
1237 |
– |
tryShrinkWorkerArray(); |
1238 |
– |
tryResumeSpare(true); // allow replacement |
1239 |
– |
} |
1240 |
– |
} |
1241 |
– |
} finally { |
1242 |
– |
lock.unlock(); |
1243 |
– |
} |
1244 |
– |
signalIdleWorkers(); |
1245 |
– |
} |
1246 |
– |
|
1247 |
– |
/** |
1248 |
– |
* Initiates termination. |
1249 |
– |
*/ |
1250 |
– |
private void terminate() { |
1251 |
– |
if (transitionRunStateTo(TERMINATING)) { |
1252 |
– |
stopAllWorkers(); |
1253 |
– |
resumeAllSpares(); |
1254 |
– |
signalIdleWorkers(); |
1255 |
– |
cancelQueuedSubmissions(); |
1256 |
– |
cancelQueuedWorkerTasks(); |
1257 |
– |
interruptUnterminatedWorkers(); |
1258 |
– |
signalIdleWorkers(); // resignal after interrupt |
1259 |
– |
} |
1260 |
– |
} |
1261 |
– |
|
1262 |
– |
/** |
1263 |
– |
* Possibly terminates when on shutdown state. |
1264 |
– |
*/ |
1265 |
– |
private void terminateOnShutdown() { |
1266 |
– |
if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl)) |
1267 |
– |
terminate(); |
1268 |
– |
} |
1269 |
– |
|
1270 |
– |
/** |
1271 |
– |
* Clears out and cancels submissions. |
1272 |
– |
*/ |
1273 |
– |
private void cancelQueuedSubmissions() { |
1274 |
– |
ForkJoinTask<?> task; |
1275 |
– |
while ((task = pollSubmission()) != null) |
1276 |
– |
task.cancel(false); |
1277 |
– |
} |
1278 |
– |
|
1279 |
– |
/** |
1280 |
– |
* Cleans out worker queues. |
1281 |
– |
*/ |
1282 |
– |
private void cancelQueuedWorkerTasks() { |
1283 |
– |
final ReentrantLock lock = this.workerLock; |
1284 |
– |
lock.lock(); |
1285 |
– |
try { |
1286 |
– |
ForkJoinWorkerThread[] ws = workers; |
1287 |
– |
if (ws != null) { |
1288 |
– |
for (int i = 0; i < ws.length; ++i) { |
1289 |
– |
ForkJoinWorkerThread t = ws[i]; |
1290 |
– |
if (t != null) |
1291 |
– |
t.cancelTasks(); |
1292 |
– |
} |
1293 |
– |
} |
1294 |
– |
} finally { |
1295 |
– |
lock.unlock(); |
1296 |
– |
} |
1297 |
– |
} |
1298 |
– |
|
1299 |
– |
/** |
1300 |
– |
* Sets each worker's status to terminating. Requires lock to avoid |
1301 |
– |
* conflicts with add/remove. |
1302 |
– |
*/ |
1303 |
– |
private void stopAllWorkers() { |
1304 |
– |
final ReentrantLock lock = this.workerLock; |
1305 |
– |
lock.lock(); |
1306 |
– |
try { |
1307 |
– |
ForkJoinWorkerThread[] ws = workers; |
1308 |
– |
if (ws != null) { |
1309 |
– |
for (int i = 0; i < ws.length; ++i) { |
1310 |
– |
ForkJoinWorkerThread t = ws[i]; |
1311 |
– |
if (t != null) |
1312 |
– |
t.shutdownNow(); |
1313 |
– |
} |
1314 |
– |
} |
1315 |
– |
} finally { |
1316 |
– |
lock.unlock(); |
1317 |
– |
} |
1318 |
– |
} |
1319 |
– |
|
1320 |
– |
/** |
1321 |
– |
* Interrupts all unterminated workers. This is not required for |
1322 |
– |
* sake of internal control, but may help unstick user code during |
1323 |
– |
* shutdown. |
1324 |
– |
*/ |
1325 |
– |
private void interruptUnterminatedWorkers() { |
1326 |
– |
final ReentrantLock lock = this.workerLock; |
1327 |
– |
lock.lock(); |
1328 |
– |
try { |
1329 |
– |
ForkJoinWorkerThread[] ws = workers; |
1330 |
– |
if (ws != null) { |
1331 |
– |
for (int i = 0; i < ws.length; ++i) { |
1332 |
– |
ForkJoinWorkerThread t = ws[i]; |
1333 |
– |
if (t != null && !t.isTerminated()) { |
1334 |
– |
try { |
1335 |
– |
t.interrupt(); |
1336 |
– |
} catch (SecurityException ignore) { |
1337 |
– |
} |
1338 |
– |
} |
1339 |
– |
} |
1340 |
– |
} |
1341 |
– |
} finally { |
1342 |
– |
lock.unlock(); |
1343 |
– |
} |
1344 |
– |
} |
1345 |
– |
|
1346 |
– |
|
1347 |
– |
/* |
1348 |
– |
* Nodes for event barrier to manage idle threads. Queue nodes |
1349 |
– |
* are basic Treiber stack nodes, also used for spare stack. |
1350 |
– |
* |
1351 |
– |
* The event barrier has an event count and a wait queue (actually |
1352 |
– |
* a Treiber stack). Workers are enabled to look for work when |
1353 |
– |
* the eventCount is incremented. If they fail to find work, they |
1354 |
– |
* may wait for next count. Upon release, threads help others wake |
1355 |
– |
* up. |
1356 |
– |
* |
1357 |
– |
* Synchronization events occur only in enough contexts to |
1358 |
– |
* maintain overall liveness: |
1359 |
– |
* |
1360 |
– |
* - Submission of a new task to the pool |
1361 |
– |
* - Resizes or other changes to the workers array |
1362 |
– |
* - pool termination |
1363 |
– |
* - A worker pushing a task on an empty queue |
1364 |
– |
* |
1365 |
– |
* The case of pushing a task occurs often enough, and is heavy |
1366 |
– |
* enough compared to simple stack pushes, to require special |
1367 |
– |
* handling: Method signalWork returns without advancing count if |
1368 |
– |
* the queue appears to be empty. This would ordinarily result in |
1369 |
– |
* races causing some queued waiters not to be woken up. To avoid |
1370 |
– |
* this, the first worker enqueued in method sync (see |
1371 |
– |
* syncIsReleasable) rescans for tasks after being enqueued, and |
1372 |
– |
* helps signal if any are found. This works well because the |
1373 |
– |
* worker has nothing better to do, and so might as well help |
1374 |
– |
* alleviate the overhead and contention on the threads actually |
1375 |
– |
* doing work. Also, since event counts increments on task |
1376 |
– |
* availability exist to maintain liveness (rather than to force |
1377 |
– |
* refreshes etc), it is OK for callers to exit early if |
1378 |
– |
* contending with another signaller. |
1379 |
– |
*/ |
1380 |
– |
static final class WaitQueueNode { |
1381 |
– |
WaitQueueNode next; // only written before enqueued |
1382 |
– |
volatile ForkJoinWorkerThread thread; // nulled to cancel wait |
1383 |
– |
final long count; // unused for spare stack |
1384 |
– |
|
1385 |
– |
WaitQueueNode(long c, ForkJoinWorkerThread w) { |
1386 |
– |
count = c; |
1387 |
– |
thread = w; |
1388 |
– |
} |
1389 |
– |
|
1390 |
– |
/** |
1391 |
– |
* Wakes up waiter, returning false if known to already |
1392 |
– |
*/ |
1393 |
– |
boolean signal() { |
1394 |
– |
ForkJoinWorkerThread t = thread; |
1395 |
– |
if (t == null) |
1396 |
– |
return false; |
1397 |
– |
thread = null; |
1398 |
– |
LockSupport.unpark(t); |
1399 |
– |
return true; |
1400 |
– |
} |
1401 |
– |
|
1402 |
– |
/** |
1403 |
– |
* Awaits release on sync. |
1404 |
– |
*/ |
1405 |
– |
void awaitSyncRelease(ForkJoinPool p) { |
1406 |
– |
while (thread != null && !p.syncIsReleasable(this)) |
1407 |
– |
LockSupport.park(this); |
1408 |
– |
} |
1409 |
– |
|
1410 |
– |
/** |
1411 |
– |
* Awaits resumption as spare. |
1412 |
– |
*/ |
1413 |
– |
void awaitSpareRelease() { |
1414 |
– |
while (thread != null) { |
1415 |
– |
if (!Thread.interrupted()) |
1416 |
– |
LockSupport.park(this); |
1417 |
– |
} |
1418 |
– |
} |
1419 |
– |
} |
1420 |
– |
|
1421 |
– |
/** |
1422 |
– |
* Ensures that no thread is waiting for count to advance from the |
1423 |
– |
* current value of eventCount read on entry to this method, by |
1424 |
– |
* releasing waiting threads if necessary. |
1425 |
– |
* |
1426 |
– |
* @return the count |
1427 |
– |
*/ |
1428 |
– |
final long ensureSync() { |
1429 |
– |
long c = eventCount; |
1430 |
– |
WaitQueueNode q; |
1431 |
– |
while ((q = syncStack) != null && q.count < c) { |
1432 |
– |
if (casBarrierStack(q, null)) { |
1433 |
– |
do { |
1434 |
– |
q.signal(); |
1435 |
– |
} while ((q = q.next) != null); |
1436 |
– |
break; |
1437 |
– |
} |
1438 |
– |
} |
1439 |
– |
return c; |
1440 |
– |
} |
1441 |
– |
|
1442 |
– |
/** |
1443 |
– |
* Increments event count and releases waiting threads. |
1444 |
– |
*/ |
1445 |
– |
private void signalIdleWorkers() { |
1446 |
– |
long c; |
1447 |
– |
do {} while (!casEventCount(c = eventCount, c+1)); |
1448 |
– |
ensureSync(); |
1449 |
– |
} |
1450 |
– |
|
1451 |
– |
/** |
1452 |
– |
* Signals threads waiting to poll a task. Because method sync |
1453 |
– |
* rechecks availability, it is OK to only proceed if queue |
1454 |
– |
* appears to be non-empty, and OK to skip under contention to |
1455 |
– |
* increment count (since some other thread succeeded). |
1456 |
– |
*/ |
1457 |
– |
final void signalWork() { |
1458 |
– |
long c; |
1459 |
– |
WaitQueueNode q; |
1460 |
– |
if (syncStack != null && |
1461 |
– |
casEventCount(c = eventCount, c+1) && |
1462 |
– |
(((q = syncStack) != null && q.count <= c) && |
1463 |
– |
(!casBarrierStack(q, q.next) || !q.signal()))) |
1464 |
– |
ensureSync(); |
1465 |
– |
} |
1466 |
– |
|
1467 |
– |
/** |
1468 |
– |
* Waits until event count advances from last value held by |
1469 |
– |
* caller, or if excess threads, caller is resumed as spare, or |
1470 |
– |
* caller or pool is terminating. Updates caller's event on exit. |
1471 |
– |
* |
1472 |
– |
* @param w the calling worker thread |
1473 |
– |
*/ |
1474 |
– |
final void sync(ForkJoinWorkerThread w) { |
1475 |
– |
updateStealCount(w); // Transfer w's count while it is idle |
1476 |
– |
|
1477 |
– |
while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) { |
1478 |
– |
long prev = w.lastEventCount; |
1479 |
– |
WaitQueueNode node = null; |
1480 |
– |
WaitQueueNode h; |
1481 |
– |
while (eventCount == prev && |
1482 |
– |
((h = syncStack) == null || h.count == prev)) { |
1483 |
– |
if (node == null) |
1484 |
– |
node = new WaitQueueNode(prev, w); |
1485 |
– |
if (casBarrierStack(node.next = h, node)) { |
1486 |
– |
node.awaitSyncRelease(this); |
1487 |
– |
break; |
1488 |
– |
} |
1489 |
– |
} |
1490 |
– |
long ec = ensureSync(); |
1491 |
– |
if (ec != prev) { |
1492 |
– |
w.lastEventCount = ec; |
1493 |
– |
break; |
1494 |
– |
} |
1495 |
– |
} |
1496 |
– |
} |
1497 |
– |
|
1498 |
– |
/** |
1499 |
– |
* Returns true if worker waiting on sync can proceed: |
1500 |
– |
* - on signal (thread == null) |
1501 |
– |
* - on event count advance (winning race to notify vs signaller) |
1502 |
– |
* - on interrupt |
1503 |
– |
* - if the first queued node, we find work available |
1504 |
– |
* If node was not signalled and event count not advanced on exit, |
1505 |
– |
* then we also help advance event count. |
1506 |
– |
* |
1507 |
– |
* @return true if node can be released |
1508 |
– |
*/ |
1509 |
– |
final boolean syncIsReleasable(WaitQueueNode node) { |
1510 |
– |
long prev = node.count; |
1511 |
– |
if (!Thread.interrupted() && node.thread != null && |
1512 |
– |
(node.next != null || |
1513 |
– |
!ForkJoinWorkerThread.hasQueuedTasks(workers)) && |
1514 |
– |
eventCount == prev) |
1515 |
– |
return false; |
1516 |
– |
if (node.thread != null) { |
1517 |
– |
node.thread = null; |
1518 |
– |
long ec = eventCount; |
1519 |
– |
if (prev <= ec) // help signal |
1520 |
– |
casEventCount(ec, ec+1); |
1521 |
– |
} |
1522 |
– |
return true; |
1523 |
– |
} |
1524 |
– |
|
1525 |
– |
/** |
1526 |
– |
* Returns true if a new sync event occurred since last call to |
1527 |
– |
* sync or this method, if so, updating caller's count. |
1528 |
– |
*/ |
1529 |
– |
final boolean hasNewSyncEvent(ForkJoinWorkerThread w) { |
1530 |
– |
long lc = w.lastEventCount; |
1531 |
– |
long ec = ensureSync(); |
1532 |
– |
if (ec == lc) |
1533 |
– |
return false; |
1534 |
– |
w.lastEventCount = ec; |
1535 |
– |
return true; |
1536 |
– |
} |
1537 |
– |
|
1538 |
– |
// Parallelism maintenance |
1539 |
– |
|
1540 |
– |
/** |
1541 |
– |
* Decrements running count; if too low, adds spare. |
1542 |
– |
* |
1543 |
– |
* Conceptually, all we need to do here is add or resume a |
1544 |
– |
* spare thread when one is about to block (and remove or |
1545 |
– |
* suspend it later when unblocked -- see suspendIfSpare). |
1546 |
– |
* However, implementing this idea requires coping with |
1547 |
– |
* several problems: we have imperfect information about the |
1548 |
– |
* states of threads. Some count updates can and usually do |
1549 |
– |
* lag run state changes, despite arrangements to keep them |
1550 |
– |
* accurate (for example, when possible, updating counts |
1551 |
– |
* before signalling or resuming), especially when running on |
1552 |
– |
* dynamic JVMs that don't optimize the infrequent paths that |
1553 |
– |
* update counts. Generating too many threads can make these |
1554 |
– |
* problems become worse, because excess threads are more |
1555 |
– |
* likely to be context-switched with others, slowing them all |
1556 |
– |
* down, especially if there is no work available, so all are |
1557 |
– |
* busy scanning or idling. Also, excess spare threads can |
1558 |
– |
* only be suspended or removed when they are idle, not |
1559 |
– |
* immediately when they aren't needed. So adding threads will |
1560 |
– |
* raise parallelism level for longer than necessary. Also, |
1561 |
– |
* FJ applications often encounter highly transient peaks when |
1562 |
– |
* many threads are blocked joining, but for less time than it |
1563 |
– |
* takes to create or resume spares. |
1564 |
– |
* |
1565 |
– |
* @param joinMe if non-null, return early if done |
1566 |
– |
* @param maintainParallelism if true, try to stay within |
1567 |
– |
* target counts, else create only to avoid starvation |
1568 |
– |
* @return true if joinMe known to be done |
1569 |
– |
*/ |
1570 |
– |
final boolean preJoin(ForkJoinTask<?> joinMe, |
1571 |
– |
boolean maintainParallelism) { |
1572 |
– |
maintainParallelism &= maintainsParallelism; // overrride |
1573 |
– |
boolean dec = false; // true when running count decremented |
1574 |
– |
while (spareStack == null || !tryResumeSpare(dec)) { |
1575 |
– |
int counts = workerCounts; |
1576 |
– |
if (dec || (dec = casWorkerCounts(counts, --counts))) { |
1577 |
– |
// CAS cheat |
1578 |
– |
if (!needSpare(counts, maintainParallelism)) |
1579 |
– |
break; |
1580 |
– |
if (joinMe.status < 0) |
1581 |
– |
return true; |
1582 |
– |
if (tryAddSpare(counts)) |
1583 |
– |
break; |
1584 |
– |
} |
1585 |
– |
} |
1586 |
– |
return false; |
1587 |
– |
} |
1588 |
– |
|
1589 |
– |
/** |
1590 |
– |
* Same idea as preJoin |
1591 |
– |
*/ |
1592 |
– |
final boolean preBlock(ManagedBlocker blocker, |
1593 |
– |
boolean maintainParallelism) { |
1594 |
– |
maintainParallelism &= maintainsParallelism; |
1595 |
– |
boolean dec = false; |
1596 |
– |
while (spareStack == null || !tryResumeSpare(dec)) { |
1597 |
– |
int counts = workerCounts; |
1598 |
– |
if (dec || (dec = casWorkerCounts(counts, --counts))) { |
1599 |
– |
if (!needSpare(counts, maintainParallelism)) |
1600 |
– |
break; |
1601 |
– |
if (blocker.isReleasable()) |
1602 |
– |
return true; |
1603 |
– |
if (tryAddSpare(counts)) |
1604 |
– |
break; |
1605 |
– |
} |
1606 |
– |
} |
1607 |
– |
return false; |
1608 |
– |
} |
1609 |
– |
|
1610 |
– |
/** |
1611 |
– |
* Returns true if a spare thread appears to be needed. If |
1612 |
– |
* maintaining parallelism, returns true when the deficit in |
1613 |
– |
* running threads is more than the surplus of total threads, and |
1614 |
– |
* there is apparently some work to do. This self-limiting rule |
1615 |
– |
* means that the more threads that have already been added, the |
1616 |
– |
* less parallelism we will tolerate before adding another. |
1617 |
– |
* |
1618 |
– |
* @param counts current worker counts |
1619 |
– |
* @param maintainParallelism try to maintain parallelism |
1620 |
– |
*/ |
1621 |
– |
private boolean needSpare(int counts, boolean maintainParallelism) { |
1622 |
– |
int ps = parallelism; |
1623 |
– |
int rc = runningCountOf(counts); |
1624 |
– |
int tc = totalCountOf(counts); |
1625 |
– |
int runningDeficit = ps - rc; |
1626 |
– |
int totalSurplus = tc - ps; |
1627 |
– |
return (tc < maxPoolSize && |
1628 |
– |
(rc == 0 || totalSurplus < 0 || |
1629 |
– |
(maintainParallelism && |
1630 |
– |
runningDeficit > totalSurplus && |
1631 |
– |
ForkJoinWorkerThread.hasQueuedTasks(workers)))); |
1632 |
– |
} |
1633 |
– |
|
1634 |
– |
/** |
1635 |
– |
* Adds a spare worker if lock available and no more than the |
1636 |
– |
* expected numbers of threads exist. |
1637 |
– |
* |
1638 |
– |
* @return true if successful |
1639 |
– |
*/ |
1640 |
– |
private boolean tryAddSpare(int expectedCounts) { |
1641 |
– |
final ReentrantLock lock = this.workerLock; |
1642 |
– |
int expectedRunning = runningCountOf(expectedCounts); |
1643 |
– |
int expectedTotal = totalCountOf(expectedCounts); |
1644 |
– |
boolean success = false; |
1645 |
– |
boolean locked = false; |
1646 |
– |
// confirm counts while locking; CAS after obtaining lock |
1647 |
– |
try { |
1648 |
– |
for (;;) { |
1649 |
– |
int s = workerCounts; |
1650 |
– |
int tc = totalCountOf(s); |
1651 |
– |
int rc = runningCountOf(s); |
1652 |
– |
if (rc > expectedRunning || tc > expectedTotal) |
1653 |
– |
break; |
1654 |
– |
if (!locked && !(locked = lock.tryLock())) |
1655 |
– |
break; |
1656 |
– |
if (casWorkerCounts(s, workerCountsFor(tc+1, rc+1))) { |
1657 |
– |
createAndStartSpare(tc); |
1658 |
– |
success = true; |
1659 |
– |
break; |
1660 |
– |
} |
1661 |
– |
} |
1662 |
– |
} finally { |
1663 |
– |
if (locked) |
1664 |
– |
lock.unlock(); |
1665 |
– |
} |
1666 |
– |
return success; |
1667 |
– |
} |
1668 |
– |
|
1669 |
– |
/** |
1670 |
– |
* Adds the kth spare worker. On entry, pool counts are already |
1671 |
– |
* adjusted to reflect addition. |
1672 |
– |
*/ |
1673 |
– |
private void createAndStartSpare(int k) { |
1674 |
– |
ForkJoinWorkerThread w = null; |
1675 |
– |
ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(k + 1); |
1676 |
– |
int len = ws.length; |
1677 |
– |
// Probably, we can place at slot k. If not, find empty slot |
1678 |
– |
if (k < len && ws[k] != null) { |
1679 |
– |
for (k = 0; k < len && ws[k] != null; ++k) |
1680 |
– |
; |
1681 |
– |
} |
1682 |
– |
if (k < len && !isTerminating() && (w = createWorker(k)) != null) { |
1683 |
– |
ws[k] = w; |
1684 |
– |
w.start(); |
1685 |
– |
} |
1686 |
– |
else |
1687 |
– |
updateWorkerCount(-1); // adjust on failure |
1688 |
– |
signalIdleWorkers(); |
1689 |
– |
} |
1690 |
– |
|
1691 |
– |
/** |
1692 |
– |
* Suspends calling thread w if there are excess threads. Called |
1693 |
– |
* only from sync. Spares are enqueued in a Treiber stack using |
1694 |
– |
* the same WaitQueueNodes as barriers. They are resumed mainly |
1695 |
– |
* in preJoin, but are also woken on pool events that require all |
1696 |
– |
* threads to check run state. |
1697 |
– |
* |
1698 |
– |
* @param w the caller |
1699 |
– |
*/ |
1700 |
– |
private boolean suspendIfSpare(ForkJoinWorkerThread w) { |
1701 |
– |
WaitQueueNode node = null; |
1702 |
– |
int s; |
1703 |
– |
while (parallelism < runningCountOf(s = workerCounts)) { |
1704 |
– |
if (node == null) |
1705 |
– |
node = new WaitQueueNode(0, w); |
1706 |
– |
if (casWorkerCounts(s, s-1)) { // representation-dependent |
1707 |
– |
// push onto stack |
1708 |
– |
do {} while (!casSpareStack(node.next = spareStack, node)); |
1709 |
– |
// block until released by resumeSpare |
1710 |
– |
node.awaitSpareRelease(); |
1711 |
– |
return true; |
1712 |
– |
} |
1713 |
– |
} |
1714 |
– |
return false; |
1715 |
– |
} |
1716 |
– |
|
1717 |
– |
/** |
1718 |
– |
* Tries to pop and resume a spare thread. |
1719 |
– |
* |
1720 |
– |
* @param updateCount if true, increment running count on success |
1721 |
– |
* @return true if successful |
1722 |
– |
*/ |
1723 |
– |
private boolean tryResumeSpare(boolean updateCount) { |
1724 |
– |
WaitQueueNode q; |
1725 |
– |
while ((q = spareStack) != null) { |
1726 |
– |
if (casSpareStack(q, q.next)) { |
1727 |
– |
if (updateCount) |
1728 |
– |
updateRunningCount(1); |
1729 |
– |
q.signal(); |
1730 |
– |
return true; |
1731 |
– |
} |
1732 |
– |
} |
1733 |
– |
return false; |
1734 |
– |
} |
1735 |
– |
|
1736 |
– |
/** |
1737 |
– |
* Pops and resumes all spare threads. Same idea as ensureSync. |
1738 |
– |
* |
1739 |
– |
* @return true if any spares released |
1740 |
– |
*/ |
1741 |
– |
private boolean resumeAllSpares() { |
1742 |
– |
WaitQueueNode q; |
1743 |
– |
while ( (q = spareStack) != null) { |
1744 |
– |
if (casSpareStack(q, null)) { |
1745 |
– |
do { |
1746 |
– |
updateRunningCount(1); |
1747 |
– |
q.signal(); |
1748 |
– |
} while ((q = q.next) != null); |
1749 |
– |
return true; |
1750 |
– |
} |
1751 |
– |
} |
1752 |
– |
return false; |
1753 |
– |
} |
1754 |
– |
|
1755 |
– |
/** |
1756 |
– |
* Pops and shuts down excessive spare threads. Call only while |
1757 |
– |
* holding lock. This is not guaranteed to eliminate all excess |
1758 |
– |
* threads, only those suspended as spares, which are the ones |
1759 |
– |
* unlikely to be needed in the future. |
1760 |
– |
*/ |
1761 |
– |
private void trimSpares() { |
1762 |
– |
int surplus = totalCountOf(workerCounts) - parallelism; |
1763 |
– |
WaitQueueNode q; |
1764 |
– |
while (surplus > 0 && (q = spareStack) != null) { |
1765 |
– |
if (casSpareStack(q, null)) { |
1766 |
– |
do { |
1767 |
– |
updateRunningCount(1); |
1768 |
– |
ForkJoinWorkerThread w = q.thread; |
1769 |
– |
if (w != null && surplus > 0 && |
1770 |
– |
runningCountOf(workerCounts) > 0 && w.shutdown()) |
1771 |
– |
--surplus; |
1772 |
– |
q.signal(); |
1773 |
– |
} while ((q = q.next) != null); |
1774 |
– |
} |
1775 |
– |
} |
1776 |
– |
} |
1777 |
– |
|
1984 |
|
/** |
1985 |
|
* Interface for extending managed parallelism for tasks running |
1986 |
< |
* in ForkJoinPools. A ManagedBlocker provides two methods. |
1987 |
< |
* Method {@code isReleasable} must return true if blocking is not |
1988 |
< |
* necessary. Method {@code block} blocks the current thread if |
1989 |
< |
* necessary (perhaps internally invoking {@code isReleasable} |
1990 |
< |
* before actually blocking.). |
1986 |
> |
* in {@link ForkJoinPool}s. |
1987 |
> |
* |
1988 |
> |
* <p>A {@code ManagedBlocker} provides two methods. Method |
1989 |
> |
* {@code isReleasable} must return {@code true} if blocking is |
1990 |
> |
* not necessary. Method {@code block} blocks the current thread |
1991 |
> |
* if necessary (perhaps internally invoking {@code isReleasable} |
1992 |
> |
* before actually blocking). These actions are performed by any |
1993 |
> |
* thread invoking {@link ForkJoinPool#managedBlock}. The |
1994 |
> |
* unusual methods in this API accommodate synchronizers that may, |
1995 |
> |
* but don't usually, block for long periods. Similarly, they |
1996 |
> |
* allow more efficient internal handling of cases in which |
1997 |
> |
* additional workers may be, but usually are not, needed to |
1998 |
> |
* ensure sufficient parallelism. Toward this end, |
1999 |
> |
* implementations of method {@code isReleasable} must be amenable |
2000 |
> |
* to repeated invocation. |
2001 |
|
* |
2002 |
|
* <p>For example, here is a ManagedBlocker based on a |
2003 |
|
* ReentrantLock: |
2015 |
|
* return hasLock || (hasLock = lock.tryLock()); |
2016 |
|
* } |
2017 |
|
* }}</pre> |
2018 |
+ |
* |
2019 |
+ |
* <p>Here is a class that possibly blocks waiting for an |
2020 |
+ |
* item on a given queue: |
2021 |
+ |
* <pre> {@code |
2022 |
+ |
* class QueueTaker<E> implements ManagedBlocker { |
2023 |
+ |
* final BlockingQueue<E> queue; |
2024 |
+ |
* volatile E item = null; |
2025 |
+ |
* QueueTaker(BlockingQueue<E> q) { this.queue = q; } |
2026 |
+ |
* public boolean block() throws InterruptedException { |
2027 |
+ |
* if (item == null) |
2028 |
+ |
* item = queue.take(); |
2029 |
+ |
* return true; |
2030 |
+ |
* } |
2031 |
+ |
* public boolean isReleasable() { |
2032 |
+ |
* return item != null || (item = queue.poll()) != null; |
2033 |
+ |
* } |
2034 |
+ |
* public E getItem() { // call after pool.managedBlock completes |
2035 |
+ |
* return item; |
2036 |
+ |
* } |
2037 |
+ |
* }}</pre> |
2038 |
|
*/ |
2039 |
|
public static interface ManagedBlocker { |
2040 |
|
/** |
2041 |
|
* Possibly blocks the current thread, for example waiting for |
2042 |
|
* a lock or condition. |
2043 |
|
* |
2044 |
< |
* @return true if no additional blocking is necessary (i.e., |
2045 |
< |
* if isReleasable would return true) |
2044 |
> |
* @return {@code true} if no additional blocking is necessary |
2045 |
> |
* (i.e., if isReleasable would return true) |
2046 |
|
* @throws InterruptedException if interrupted while waiting |
2047 |
|
* (the method is not required to do so, but is allowed to) |
2048 |
|
*/ |
2049 |
|
boolean block() throws InterruptedException; |
2050 |
|
|
2051 |
|
/** |
2052 |
< |
* Returns true if blocking is unnecessary. |
2052 |
> |
* Returns {@code true} if blocking is unnecessary. |
2053 |
|
*/ |
2054 |
|
boolean isReleasable(); |
2055 |
|
} |
2056 |
|
|
2057 |
|
/** |
2058 |
|
* Blocks in accord with the given blocker. If the current thread |
2059 |
< |
* is a ForkJoinWorkerThread, this method possibly arranges for a |
2060 |
< |
* spare thread to be activated if necessary to ensure parallelism |
2061 |
< |
* while the current thread is blocked. If |
1826 |
< |
* {@code maintainParallelism} is true and the pool supports |
1827 |
< |
* it ({@link #getMaintainsParallelism}), this method attempts to |
1828 |
< |
* maintain the pool's nominal parallelism. Otherwise it activates |
1829 |
< |
* a thread only if necessary to avoid complete starvation. This |
1830 |
< |
* option may be preferable when blockages use timeouts, or are |
1831 |
< |
* almost always brief. |
2059 |
> |
* is a {@link ForkJoinWorkerThread}, this method possibly |
2060 |
> |
* arranges for a spare thread to be activated if necessary to |
2061 |
> |
* ensure sufficient parallelism while the current thread is blocked. |
2062 |
|
* |
2063 |
< |
* <p> If the caller is not a ForkJoinTask, this method is behaviorally |
2064 |
< |
* equivalent to |
2063 |
> |
* <p>If the caller is not a {@link ForkJoinTask}, this method is |
2064 |
> |
* behaviorally equivalent to |
2065 |
|
* <pre> {@code |
2066 |
|
* while (!blocker.isReleasable()) |
2067 |
|
* if (blocker.block()) |
2068 |
|
* return; |
2069 |
|
* }</pre> |
2070 |
< |
* If the caller is a ForkJoinTask, then the pool may first |
2071 |
< |
* be expanded to ensure parallelism, and later adjusted. |
2070 |
> |
* |
2071 |
> |
* If the caller is a {@code ForkJoinTask}, then the pool may |
2072 |
> |
* first be expanded to ensure parallelism, and later adjusted. |
2073 |
|
* |
2074 |
|
* @param blocker the blocker |
1844 |
– |
* @param maintainParallelism if true and supported by this pool, |
1845 |
– |
* attempt to maintain the pool's nominal parallelism; otherwise |
1846 |
– |
* activate a thread only if necessary to avoid complete |
1847 |
– |
* starvation. |
2075 |
|
* @throws InterruptedException if blocker.block did so |
2076 |
|
*/ |
2077 |
< |
public static void managedBlock(ManagedBlocker blocker, |
1851 |
< |
boolean maintainParallelism) |
2077 |
> |
public static void managedBlock(ManagedBlocker blocker) |
2078 |
|
throws InterruptedException { |
2079 |
|
Thread t = Thread.currentThread(); |
2080 |
< |
ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ? |
2081 |
< |
((ForkJoinWorkerThread) t).pool : null); |
2082 |
< |
if (!blocker.isReleasable()) { |
2083 |
< |
try { |
2084 |
< |
if (pool == null || |
2085 |
< |
!pool.preBlock(blocker, maintainParallelism)) |
1860 |
< |
awaitBlocker(blocker); |
1861 |
< |
} finally { |
1862 |
< |
if (pool != null) |
1863 |
< |
pool.updateRunningCount(1); |
1864 |
< |
} |
2080 |
> |
if (t instanceof ForkJoinWorkerThread) { |
2081 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
2082 |
> |
w.pool.awaitBlocker(blocker); |
2083 |
> |
} |
2084 |
> |
else { |
2085 |
> |
do {} while (!blocker.isReleasable() && !blocker.block()); |
2086 |
|
} |
2087 |
|
} |
2088 |
|
|
2089 |
< |
private static void awaitBlocker(ManagedBlocker blocker) |
2090 |
< |
throws InterruptedException { |
2091 |
< |
do {} while (!blocker.isReleasable() && !blocker.block()); |
1871 |
< |
} |
1872 |
< |
|
1873 |
< |
// AbstractExecutorService overrides |
2089 |
> |
// AbstractExecutorService overrides. These rely on undocumented |
2090 |
> |
// fact that ForkJoinTask.adapt returns ForkJoinTasks that also |
2091 |
> |
// implement RunnableFuture. |
2092 |
|
|
2093 |
|
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { |
2094 |
< |
return new AdaptedRunnable<T>(runnable, value); |
2094 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value); |
2095 |
|
} |
2096 |
|
|
2097 |
|
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { |
2098 |
< |
return new AdaptedCallable<T>(callable); |
2098 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(callable); |
2099 |
|
} |
2100 |
|
|
2101 |
+ |
// Unsafe mechanics |
2102 |
+ |
private static final sun.misc.Unsafe UNSAFE; |
2103 |
+ |
private static final long ctlOffset; |
2104 |
+ |
private static final long stealCountOffset; |
2105 |
+ |
private static final long blockedCountOffset; |
2106 |
+ |
private static final long quiescerCountOffset; |
2107 |
+ |
private static final long scanGuardOffset; |
2108 |
+ |
private static final long nextWorkerNumberOffset; |
2109 |
+ |
private static final long ABASE; |
2110 |
+ |
private static final int ASHIFT; |
2111 |
+ |
|
2112 |
+ |
static { |
2113 |
+ |
poolNumberGenerator = new AtomicInteger(); |
2114 |
+ |
workerSeedGenerator = new Random(); |
2115 |
+ |
modifyThreadPermission = new RuntimePermission("modifyThread"); |
2116 |
+ |
defaultForkJoinWorkerThreadFactory = |
2117 |
+ |
new DefaultForkJoinWorkerThreadFactory(); |
2118 |
+ |
try { |
2119 |
+ |
UNSAFE = getUnsafe(); |
2120 |
+ |
Class<?> k = ForkJoinPool.class; |
2121 |
+ |
ctlOffset = UNSAFE.objectFieldOffset |
2122 |
+ |
(k.getDeclaredField("ctl")); |
2123 |
+ |
stealCountOffset = UNSAFE.objectFieldOffset |
2124 |
+ |
(k.getDeclaredField("stealCount")); |
2125 |
+ |
blockedCountOffset = UNSAFE.objectFieldOffset |
2126 |
+ |
(k.getDeclaredField("blockedCount")); |
2127 |
+ |
quiescerCountOffset = UNSAFE.objectFieldOffset |
2128 |
+ |
(k.getDeclaredField("quiescerCount")); |
2129 |
+ |
scanGuardOffset = UNSAFE.objectFieldOffset |
2130 |
+ |
(k.getDeclaredField("scanGuard")); |
2131 |
+ |
nextWorkerNumberOffset = UNSAFE.objectFieldOffset |
2132 |
+ |
(k.getDeclaredField("nextWorkerNumber")); |
2133 |
+ |
} catch (Exception e) { |
2134 |
+ |
throw new Error(e); |
2135 |
+ |
} |
2136 |
+ |
Class<?> a = ForkJoinTask[].class; |
2137 |
+ |
ABASE = UNSAFE.arrayBaseOffset(a); |
2138 |
+ |
int s = UNSAFE.arrayIndexScale(a); |
2139 |
+ |
if ((s & (s-1)) != 0) |
2140 |
+ |
throw new Error("data type scale not a power of two"); |
2141 |
+ |
ASHIFT = 31 - Integer.numberOfLeadingZeros(s); |
2142 |
+ |
} |
2143 |
|
|
2144 |
< |
// Unsafe mechanics for jsr166y 3rd party package. |
2144 |
> |
/** |
2145 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
2146 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
2147 |
> |
* into a jdk. |
2148 |
> |
* |
2149 |
> |
* @return a sun.misc.Unsafe |
2150 |
> |
*/ |
2151 |
|
private static sun.misc.Unsafe getUnsafe() { |
2152 |
|
try { |
2153 |
|
return sun.misc.Unsafe.getUnsafe(); |
2154 |
|
} catch (SecurityException se) { |
2155 |
|
try { |
2156 |
|
return java.security.AccessController.doPrivileged |
2157 |
< |
(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
2157 |
> |
(new java.security |
2158 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
2159 |
|
public sun.misc.Unsafe run() throws Exception { |
2160 |
< |
return getUnsafeByReflection(); |
2160 |
> |
java.lang.reflect.Field f = sun.misc |
2161 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
2162 |
> |
f.setAccessible(true); |
2163 |
> |
return (sun.misc.Unsafe) f.get(null); |
2164 |
|
}}); |
2165 |
|
} catch (java.security.PrivilegedActionException e) { |
2166 |
|
throw new RuntimeException("Could not initialize intrinsics", |
2168 |
|
} |
2169 |
|
} |
2170 |
|
} |
1901 |
– |
|
1902 |
– |
private static sun.misc.Unsafe getUnsafeByReflection() |
1903 |
– |
throws NoSuchFieldException, IllegalAccessException { |
1904 |
– |
java.lang.reflect.Field f = |
1905 |
– |
sun.misc.Unsafe.class.getDeclaredField("theUnsafe"); |
1906 |
– |
f.setAccessible(true); |
1907 |
– |
return (sun.misc.Unsafe) f.get(null); |
1908 |
– |
} |
1909 |
– |
|
1910 |
– |
private static long fieldOffset(String fieldName, Class<?> klazz) { |
1911 |
– |
try { |
1912 |
– |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName)); |
1913 |
– |
} catch (NoSuchFieldException e) { |
1914 |
– |
// Convert Exception to Error |
1915 |
– |
NoSuchFieldError error = new NoSuchFieldError(fieldName); |
1916 |
– |
error.initCause(e); |
1917 |
– |
throw error; |
1918 |
– |
} |
1919 |
– |
} |
1920 |
– |
|
1921 |
– |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1922 |
– |
static final long eventCountOffset = |
1923 |
– |
fieldOffset("eventCount", ForkJoinPool.class); |
1924 |
– |
static final long workerCountsOffset = |
1925 |
– |
fieldOffset("workerCounts", ForkJoinPool.class); |
1926 |
– |
static final long runControlOffset = |
1927 |
– |
fieldOffset("runControl", ForkJoinPool.class); |
1928 |
– |
static final long syncStackOffset = |
1929 |
– |
fieldOffset("syncStack",ForkJoinPool.class); |
1930 |
– |
static final long spareStackOffset = |
1931 |
– |
fieldOffset("spareStack", ForkJoinPool.class); |
1932 |
– |
|
1933 |
– |
private boolean casEventCount(long cmp, long val) { |
1934 |
– |
return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val); |
1935 |
– |
} |
1936 |
– |
private boolean casWorkerCounts(int cmp, int val) { |
1937 |
– |
return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val); |
1938 |
– |
} |
1939 |
– |
private boolean casRunControl(int cmp, int val) { |
1940 |
– |
return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val); |
1941 |
– |
} |
1942 |
– |
private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) { |
1943 |
– |
return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val); |
1944 |
– |
} |
1945 |
– |
private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) { |
1946 |
– |
return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val); |
1947 |
– |
} |
2171 |
|
} |