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*/ |
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package jsr166y; |
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import java.util.*; |
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import java.util.concurrent.*; |
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import java.util.concurrent.locks.*; |
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import java.util.concurrent.atomic.*; |
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import sun.misc.Unsafe; |
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import java.lang.reflect.*; |
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|
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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.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.TimeoutException; |
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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.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. 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</code> 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</code>) |
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* and dynamically thread construction can be limited using methods |
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* <code>setMaximumPoolSize</code> and/or |
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* <code>setMaintainsParallelism</code>. |
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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</code>) 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</code> 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 |
101 |
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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> |
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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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* } |
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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 |
115 |
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* pools with greater than the maximum result in |
116 |
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* IllegalArgumentExceptions. |
115 |
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* pools with greater than the maximum number result in |
116 |
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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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*/ |
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public class ForkJoinPool extends AbstractExecutorService { |
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|
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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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* 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 |
145 |
> |
* 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 tesks) 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 |
172 |
> |
* 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 |
182 |
> |
* of the messy code constructions here). In essence, the workers |
183 |
> |
* 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 |
185 |
> |
* references. Access to the workers in associated methods (for |
186 |
> |
* example signalWork) must both index-check and null-check the |
187 |
> |
* IDs. All such accesses ignore bad IDs by returning out early |
188 |
> |
* from what they are doing, since this can only be associated |
189 |
> |
* with termination, in which case it is OK to give up. |
190 |
> |
* |
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* All uses of the workers array, as well as queue arrays, check |
192 |
> |
* that the array is non-null (even if previously non-null). This |
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> |
* allows nulling during termination, which is currently not |
194 |
> |
* necessary, but remains an option for resource-revocation-based |
195 |
> |
* shutdown schemes. |
196 |
> |
* |
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> |
* Wait Queuing. Unlike HPC work-stealing frameworks, we cannot |
198 |
> |
* let workers spin indefinitely scanning for tasks when none are |
199 |
> |
* can be immediately found, and we cannot start/resume workers |
200 |
> |
* unless there appear to be tasks available. On the other hand, |
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* we must quickly prod them into action when new tasks are |
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> |
* submitted or generated. We park/unpark workers after placing |
203 |
> |
* in an event wait queue when they cannot find work. This "queue" |
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> |
* is actually a simple Treiber stack, headed by the "id" field of |
205 |
> |
* ctl, plus a 15bit counter value to both wake up waiters (by |
206 |
> |
* advancing their count) and avoid ABA effects. Successors are |
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> |
* held in worker field "nextWait". Queuing deals with several |
208 |
> |
* intrinsic races, mainly that a task-producing thread can miss |
209 |
> |
* seeing (and signalling) another thread that gave up looking for |
210 |
> |
* work but has not yet entered the wait queue. We solve this by |
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> |
* requiring a full sweep of all workers both before (in scan()) |
212 |
> |
* and after (in awaitWork()) a newly waiting worker is added to |
213 |
> |
* the wait queue. During a rescan, the worker might release some |
214 |
> |
* other queued worker rather than itself, which has the same net |
215 |
> |
* effect. |
216 |
> |
* |
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> |
* Signalling. We create or wake up workers only when there |
218 |
> |
* appears to be at least one task they might be able to find and |
219 |
> |
* execute. When a submission is added or another worker adds a |
220 |
> |
* 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). |
223 |
> |
* These primary signals are buttressed by signals during rescans |
224 |
> |
* as well as those performed when a worker steals a task and |
225 |
> |
* 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 |
227 |
> |
* but untaken. |
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> |
* |
229 |
> |
* Trimming workers. To release resources after periods of lack of |
230 |
> |
* use, a worker starting to wait when the pool is quiescent will |
231 |
> |
* time out and terminate if the pool has remained quiescent for |
232 |
> |
* SHRINK_RATE nanosecs. |
233 |
> |
* |
234 |
> |
* Submissions. External submissions are maintained in an |
235 |
> |
* array-based queue that is structured identically to |
236 |
> |
* ForkJoinWorkerThread queues (which see) except for the use of |
237 |
> |
* submissionLock in method addSubmission. Unlike worker queues, |
238 |
> |
* multiple external threads can add new submissions. |
239 |
> |
* |
240 |
> |
* Compensation. Beyond work-stealing support and lifecycle |
241 |
> |
* control, the main responsibility of this framework is to take |
242 |
> |
* actions when one worker is waiting to join a task stolen (or |
243 |
> |
* always held by) another. Because we are multiplexing many |
244 |
> |
* tasks on to a pool of workers, we can't just let them block (as |
245 |
> |
* in Thread.join). We also cannot just reassign the joiner's |
246 |
> |
* run-time stack with another and replace it later, which would |
247 |
> |
* be a form of "continuation", that even if possible is not |
248 |
> |
* necessarily a good idea since we sometimes need both an |
249 |
> |
* unblocked task and its continuation to progress. Instead we |
250 |
> |
* combine two tactics: |
251 |
> |
* |
252 |
> |
* Helping: Arranging for the joiner to execute some task that it |
253 |
> |
* would be running if the steal had not occurred. Method |
254 |
> |
* ForkJoinWorkerThread.joinTask tracks joining->stealing |
255 |
> |
* links to try to find such a task. |
256 |
> |
* |
257 |
> |
* Compensating: Unless there are already enough live threads, |
258 |
> |
* method tryPreBlock() may create or re-activate a spare |
259 |
> |
* thread to compensate for blocked joiners until they |
260 |
> |
* unblock. |
261 |
> |
* |
262 |
> |
* The ManagedBlocker extension API can't use helping so relies |
263 |
> |
* only on compensation in method awaitBlocker. |
264 |
> |
* |
265 |
> |
* It is impossible to keep exactly the target parallelism number |
266 |
> |
* of threads running at any given time. Determining the |
267 |
> |
* existence of conservatively safe helping targets, the |
268 |
> |
* availability of already-created spares, and the apparent need |
269 |
> |
* to create new spares are all racy and require heuristic |
270 |
> |
* guidance, so we rely on multiple retries of each. Currently, |
271 |
> |
* in keeping with on-demand signalling policy, we compensate only |
272 |
> |
* if blocking would leave less than one active (non-waiting, |
273 |
> |
* non-blocked) worker. Additionally, to avoid some false alarms |
274 |
> |
* due to GC, lagging counters, system activity, etc, compensated |
275 |
> |
* blocking for joins is only attempted after a number of rechecks |
276 |
> |
* proportional to the current apparent deficit (where retries are |
277 |
> |
* interspersed with Thread.yield, for good citizenship). The |
278 |
> |
* variable blockedCount, incremented before blocking and |
279 |
> |
* decremented after, is sometimes needed to distinguish cases of |
280 |
> |
* waiting for work vs blocking on joins or other managed sync, |
281 |
> |
* but both the cases are equivalent for most pool control, so we |
282 |
> |
* can update non-atomically. (Additionally, contention on |
283 |
> |
* blockedCount alleviates some contention on ctl). |
284 |
> |
* |
285 |
> |
* Shutdown and Termination. A call to shutdownNow atomically sets |
286 |
> |
* the ctl stop bit and then (non-atomically) sets each workers |
287 |
> |
* "terminate" status, cancels all unprocessed tasks, and wakes up |
288 |
> |
* all waiting workers. Detecting whether termination should |
289 |
> |
* commence after a non-abrupt shutdown() call requires more work |
290 |
> |
* and bookkeeping. We need consensus about quiesence (i.e., that |
291 |
> |
* there is no more work) which is reflected in active counts so |
292 |
> |
* long as there are no current blockers, as well as possible |
293 |
> |
* re-evaluations during independent changes in blocking or |
294 |
> |
* quiescing workers. |
295 |
> |
* |
296 |
> |
* Style notes: There is a lot of representation-level coupling |
297 |
> |
* among classes ForkJoinPool, ForkJoinWorkerThread, and |
298 |
> |
* ForkJoinTask. Most fields of ForkJoinWorkerThread maintain |
299 |
> |
* data structures managed by ForkJoinPool, so are directly |
300 |
> |
* accessed. Conversely we allow access to "workers" array by |
301 |
> |
* workers, and direct access to ForkJoinTask.status by both |
302 |
> |
* ForkJoinPool and ForkJoinWorkerThread. There is little point |
303 |
> |
* trying to reduce this, since any associated future changes in |
304 |
> |
* representations will need to be accompanied by algorithmic |
305 |
> |
* changes anyway. All together, these low-level implementation |
306 |
> |
* choices produce as much as a factor of 4 performance |
307 |
> |
* improvement compared to naive implementations, and enable the |
308 |
> |
* processing of billions of tasks per second, at the expense of |
309 |
> |
* some ugliness. |
310 |
> |
* |
311 |
> |
* Methods signalWork() and scan() are the main bottlenecks so are |
312 |
> |
* especially heavily micro-optimized/mangled. There are lots of |
313 |
> |
* inline assignments (of form "while ((local = field) != 0)") |
314 |
> |
* which are usually the simplest way to ensure the required read |
315 |
> |
* orderings (which are sometimes critical). This leads to a |
316 |
> |
* "C"-like style of listing declarations of these locals at the |
317 |
> |
* heads of methods or blocks. There are several occurrences of |
318 |
> |
* the unusual "do {} while (!cas...)" which is the simplest way |
319 |
> |
* to force an update of a CAS'ed variable. There are also other |
320 |
> |
* coding oddities that help some methods perform reasonably even |
321 |
> |
* when interpreted (not compiled). |
322 |
> |
* |
323 |
> |
* The order of declarations in this file is: (1) declarations of |
324 |
> |
* statics (2) fields (along with constants used when unpacking |
325 |
> |
* some of them), listed in an order that tends to reduce |
326 |
> |
* contention among them a bit under most JVMs. (3) internal |
327 |
> |
* control methods (4) callbacks and other support for |
328 |
> |
* ForkJoinTask and ForkJoinWorkerThread classes, (5) exported |
329 |
> |
* methods (plus a few little helpers). (6) static block |
330 |
> |
* initializing all statics in a minimally dependent order. |
331 |
|
*/ |
332 |
|
|
65 |
– |
/** Mask for packing and unpacking shorts */ |
66 |
– |
private static final int shortMask = 0xffff; |
67 |
– |
|
68 |
– |
/** Max pool size -- must be a power of two minus 1 */ |
69 |
– |
private static final int MAX_THREADS = 0x7FFF; |
70 |
– |
|
333 |
|
/** |
334 |
< |
* Factory for creating new ForkJoinWorkerThreads. A |
335 |
< |
* ForkJoinWorkerThreadFactory must be defined and used for |
336 |
< |
* ForkJoinWorkerThread subclasses that extend base functionality |
337 |
< |
* or initialize threads with different contexts. |
334 |
> |
* Factory for creating new {@link ForkJoinWorkerThread}s. |
335 |
> |
* A {@code ForkJoinWorkerThreadFactory} must be defined and used |
336 |
> |
* for {@code ForkJoinWorkerThread} subclasses that extend base |
337 |
> |
* functionality or initialize threads with different contexts. |
338 |
|
*/ |
339 |
|
public static interface ForkJoinWorkerThreadFactory { |
340 |
|
/** |
341 |
|
* Returns a new worker thread operating in the given pool. |
342 |
|
* |
343 |
|
* @param pool the pool this thread works in |
344 |
< |
* @throws NullPointerException if pool is null; |
344 |
> |
* @throws NullPointerException if the pool is null |
345 |
|
*/ |
346 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool); |
347 |
|
} |
348 |
|
|
349 |
|
/** |
350 |
< |
* Default ForkJoinWorkerThreadFactory implementation, creates a |
350 |
> |
* Default ForkJoinWorkerThreadFactory implementation; creates a |
351 |
|
* new ForkJoinWorkerThread. |
352 |
|
*/ |
353 |
< |
static class DefaultForkJoinWorkerThreadFactory |
353 |
> |
static class DefaultForkJoinWorkerThreadFactory |
354 |
|
implements ForkJoinWorkerThreadFactory { |
355 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool) { |
356 |
< |
try { |
95 |
< |
return new ForkJoinWorkerThread(pool); |
96 |
< |
} catch (OutOfMemoryError oom) { |
97 |
< |
return null; |
98 |
< |
} |
356 |
> |
return new ForkJoinWorkerThread(pool); |
357 |
|
} |
358 |
|
} |
359 |
|
|
362 |
|
* overridden in ForkJoinPool constructors. |
363 |
|
*/ |
364 |
|
public static final ForkJoinWorkerThreadFactory |
365 |
< |
defaultForkJoinWorkerThreadFactory = |
108 |
< |
new DefaultForkJoinWorkerThreadFactory(); |
365 |
> |
defaultForkJoinWorkerThreadFactory; |
366 |
|
|
367 |
|
/** |
368 |
|
* Permission required for callers of methods that may start or |
369 |
|
* kill threads. |
370 |
|
*/ |
371 |
< |
private static final RuntimePermission modifyThreadPermission = |
115 |
< |
new RuntimePermission("modifyThread"); |
371 |
> |
private static final RuntimePermission modifyThreadPermission; |
372 |
|
|
373 |
|
/** |
374 |
|
* If there is a security manager, makes sure caller has |
383 |
|
/** |
384 |
|
* Generator for assigning sequence numbers as pool names. |
385 |
|
*/ |
386 |
< |
private static final AtomicInteger poolNumberGenerator = |
131 |
< |
new AtomicInteger(); |
386 |
> |
private static final AtomicInteger poolNumberGenerator; |
387 |
|
|
388 |
|
/** |
389 |
< |
* Array holding all worker threads in the pool. Array size must |
390 |
< |
* be a power of two. Updates and replacements are protected by |
391 |
< |
* workerLock, but it is always kept in a consistent enough state |
392 |
< |
* to be randomly accessed without locking by workers performing |
393 |
< |
* work-stealing. |
389 |
> |
* Generator for initial random seeds for worker victim |
390 |
> |
* selection. This is used only to create initial seeds. Random |
391 |
> |
* steals use a cheaper xorshift generator per steal attempt. We |
392 |
> |
* don't expect much contention on seedGenerator, so just use a |
393 |
> |
* plain Random. |
394 |
|
*/ |
395 |
< |
volatile ForkJoinWorkerThread[] workers; |
395 |
> |
static final Random workerSeedGenerator; |
396 |
|
|
397 |
|
/** |
398 |
< |
* Lock protecting access to workers. |
398 |
> |
* Array holding all worker threads in the pool. Initialized upon |
399 |
> |
* construction. Array size must be a power of two. Updates and |
400 |
> |
* replacements are protected by scanGuard, but the array is |
401 |
> |
* always kept in a consistent enough state to be randomly |
402 |
> |
* accessed without locking by workers performing work-stealing, |
403 |
> |
* as well as other traversal-based methods in this class, so long |
404 |
> |
* as reads memory-acquire by first reading ctl. All readers must |
405 |
> |
* tolerate that some array slots may be null. |
406 |
|
*/ |
407 |
< |
private final ReentrantLock workerLock; |
407 |
> |
ForkJoinWorkerThread[] workers; |
408 |
|
|
409 |
|
/** |
410 |
< |
* Condition for awaitTermination. |
410 |
> |
* Initial size for submission queue array. Must be a power of |
411 |
> |
* two. In many applications, these always stay small so we use a |
412 |
> |
* small initial cap. |
413 |
|
*/ |
414 |
< |
private final Condition termination; |
414 |
> |
private static final int INITIAL_QUEUE_CAPACITY = 8; |
415 |
> |
|
416 |
> |
/** |
417 |
> |
* Maximum size for submission queue array. Must be a power of two |
418 |
> |
* less than or equal to 1 << (31 - width of array entry) to |
419 |
> |
* ensure lack of index wraparound, but is capped at a lower |
420 |
> |
* value to help users trap runaway computations. |
421 |
> |
*/ |
422 |
> |
private static final int MAXIMUM_QUEUE_CAPACITY = 1 << 24; // 16M |
423 |
> |
|
424 |
> |
/** |
425 |
> |
* Array serving as submission queue. Initialized upon construction. |
426 |
> |
*/ |
427 |
> |
private ForkJoinTask<?>[] submissionQueue; |
428 |
> |
|
429 |
> |
/** |
430 |
> |
* Lock protecting submissions array for addSubmission |
431 |
> |
*/ |
432 |
> |
private final ReentrantLock submissionLock; |
433 |
|
|
434 |
|
/** |
435 |
< |
* The uncaught exception handler used when any worker |
436 |
< |
* abrupty terminates |
435 |
> |
* Condition for awaitTermination, using submissionLock for |
436 |
> |
* convenience. |
437 |
|
*/ |
438 |
< |
private Thread.UncaughtExceptionHandler ueh; |
438 |
> |
private final Condition termination; |
439 |
|
|
440 |
|
/** |
441 |
|
* Creation factory for worker threads. |
443 |
|
private final ForkJoinWorkerThreadFactory factory; |
444 |
|
|
445 |
|
/** |
446 |
< |
* Head of stack of threads that were created to maintain |
447 |
< |
* parallelism when other threads blocked, but have since |
166 |
< |
* suspended when the parallelism level rose. |
446 |
> |
* The uncaught exception handler used when any worker abruptly |
447 |
> |
* terminates. |
448 |
|
*/ |
449 |
< |
private volatile WaitQueueNode spareStack; |
449 |
> |
final Thread.UncaughtExceptionHandler ueh; |
450 |
> |
|
451 |
> |
/** |
452 |
> |
* Prefix for assigning names to worker threads |
453 |
> |
*/ |
454 |
> |
private final String workerNamePrefix; |
455 |
|
|
456 |
|
/** |
457 |
|
* Sum of per-thread steal counts, updated only when threads are |
458 |
|
* idle or terminating. |
459 |
|
*/ |
460 |
< |
private final AtomicLong stealCount; |
460 |
> |
private volatile long stealCount; |
461 |
|
|
462 |
|
/** |
463 |
< |
* Queue for external submissions. |
463 |
> |
* Main pool control -- a long packed with: |
464 |
> |
* AC: Number of active running workers minus target parallelism (16 bits) |
465 |
> |
* TC: Number of total workers minus target parallelism (16bits) |
466 |
> |
* ST: true if pool is terminating (1 bit) |
467 |
> |
* EC: the wait count of top waiting thread (15 bits) |
468 |
> |
* ID: ~poolIndex of top of Treiber stack of waiting threads (16 bits) |
469 |
> |
* |
470 |
> |
* When convenient, we can extract the upper 32 bits of counts and |
471 |
> |
* the lower 32 bits of queue state, u = (int)(ctl >>> 32) and e = |
472 |
> |
* (int)ctl. The ec field is never accessed alone, but always |
473 |
> |
* together with id and st. The offsets of counts by the target |
474 |
> |
* parallelism and the positionings of fields makes it possible to |
475 |
> |
* perform the most common checks via sign tests of fields: When |
476 |
> |
* ac is negative, there are not enough active workers, when tc is |
477 |
> |
* negative, there are not enough total workers, when id is |
478 |
> |
* negative, there is at least one waiting worker, and when e is |
479 |
> |
* negative, the pool is terminating. To deal with these possibly |
480 |
> |
* negative fields, we use casts in and out of "short" and/or |
481 |
> |
* signed shifts to maintain signedness. Note: AC_SHIFT is |
482 |
> |
* redundantly declared in ForkJoinWorkerThread in order to |
483 |
> |
* integrate a surplus-threads check. |
484 |
|
*/ |
485 |
< |
private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue; |
485 |
> |
volatile long ctl; |
486 |
> |
|
487 |
> |
// bit positions/shifts for fields |
488 |
> |
private static final int AC_SHIFT = 48; |
489 |
> |
private static final int TC_SHIFT = 32; |
490 |
> |
private static final int ST_SHIFT = 31; |
491 |
> |
private static final int EC_SHIFT = 16; |
492 |
> |
|
493 |
> |
// bounds |
494 |
> |
private static final int MAX_ID = 0x7fff; // max poolIndex |
495 |
> |
private static final int SMASK = 0xffff; // mask short bits |
496 |
> |
private static final int SHORT_SIGN = 1 << 15; |
497 |
> |
private static final int INT_SIGN = 1 << 31; |
498 |
> |
|
499 |
> |
// masks |
500 |
> |
private static final long STOP_BIT = 0x0001L << ST_SHIFT; |
501 |
> |
private static final long AC_MASK = ((long)SMASK) << AC_SHIFT; |
502 |
> |
private static final long TC_MASK = ((long)SMASK) << TC_SHIFT; |
503 |
> |
|
504 |
> |
// units for incrementing and decrementing |
505 |
> |
private static final long TC_UNIT = 1L << TC_SHIFT; |
506 |
> |
private static final long AC_UNIT = 1L << AC_SHIFT; |
507 |
> |
|
508 |
> |
// masks and units for dealing with u = (int)(ctl >>> 32) |
509 |
> |
private static final int UAC_SHIFT = AC_SHIFT - 32; |
510 |
> |
private static final int UTC_SHIFT = TC_SHIFT - 32; |
511 |
> |
private static final int UAC_MASK = SMASK << UAC_SHIFT; |
512 |
> |
private static final int UTC_MASK = SMASK << UTC_SHIFT; |
513 |
> |
private static final int UAC_UNIT = 1 << UAC_SHIFT; |
514 |
> |
private static final int UTC_UNIT = 1 << UTC_SHIFT; |
515 |
> |
|
516 |
> |
// masks and units for dealing with e = (int)ctl |
517 |
> |
private static final int E_MASK = 0x7fffffff; // no STOP_BIT |
518 |
> |
private static final int EC_UNIT = 1 << EC_SHIFT; |
519 |
|
|
520 |
|
/** |
521 |
< |
* Head of Treiber stack for barrier sync. See below for explanation |
521 |
> |
* The target parallelism level. |
522 |
|
*/ |
523 |
< |
private volatile WaitQueueNode barrierStack; |
523 |
> |
final int parallelism; |
524 |
|
|
525 |
|
/** |
526 |
< |
* The count for event barrier |
526 |
> |
* Index (mod submission queue length) of next element to take |
527 |
> |
* from submission queue. |
528 |
|
*/ |
529 |
< |
private volatile long eventCount; |
529 |
> |
volatile int queueBase; |
530 |
|
|
531 |
|
/** |
532 |
< |
* Pool number, just for assigning useful names to worker threads |
532 |
> |
* Index (mod submission queue length) of next element to add |
533 |
> |
* in submission queue. |
534 |
|
*/ |
535 |
< |
private final int poolNumber; |
535 |
> |
int queueTop; |
536 |
|
|
537 |
|
/** |
538 |
< |
* The maximum allowed pool size |
538 |
> |
* True when shutdown() has been called. |
539 |
|
*/ |
540 |
< |
private volatile int maxPoolSize; |
540 |
> |
volatile boolean shutdown; |
541 |
|
|
542 |
|
/** |
543 |
< |
* The desired parallelism level, updated only under workerLock. |
543 |
> |
* True if use local fifo, not default lifo, for local polling |
544 |
> |
* Read by, and replicated by ForkJoinWorkerThreads |
545 |
|
*/ |
546 |
< |
private volatile int parallelism; |
546 |
> |
final boolean locallyFifo; |
547 |
|
|
548 |
|
/** |
549 |
< |
* Holds number of total (i.e., created and not yet terminated) |
550 |
< |
* and running (i.e., not blocked on joins or other managed sync) |
551 |
< |
* threads, packed into one int to ensure consistent snapshot when |
210 |
< |
* making decisions about creating and suspending spare |
211 |
< |
* threads. Updated only by CAS. Note: CASes in |
212 |
< |
* updateRunningCount and preJoin running active count is in low |
213 |
< |
* word, so need to be modified if this changes |
549 |
> |
* The number of threads in ForkJoinWorkerThreads.helpQuiescePool. |
550 |
> |
* When non-zero, suppresses automatic shutdown when active |
551 |
> |
* counts become zero. |
552 |
|
*/ |
553 |
< |
private volatile int workerCounts; |
553 |
> |
volatile int quiescerCount; |
554 |
|
|
555 |
< |
private static int totalCountOf(int s) { return s >>> 16; } |
556 |
< |
private static int runningCountOf(int s) { return s & shortMask; } |
557 |
< |
private static int workerCountsFor(int t, int r) { return (t << 16) + r; } |
555 |
> |
/** |
556 |
> |
* The number of threads blocked in join. |
557 |
> |
*/ |
558 |
> |
volatile int blockedCount; |
559 |
|
|
560 |
|
/** |
561 |
< |
* Add delta (which may be negative) to running count. This must |
223 |
< |
* be called before (with negative arg) and after (with positive) |
224 |
< |
* any managed synchronization (i.e., mainly, joins) |
225 |
< |
* @param delta the number to add |
561 |
> |
* Counter for worker Thread names (unrelated to their poolIndex) |
562 |
|
*/ |
563 |
< |
final void updateRunningCount(int delta) { |
228 |
< |
int s; |
229 |
< |
do;while (!casWorkerCounts(s = workerCounts, s + delta)); |
230 |
< |
} |
563 |
> |
private volatile int nextWorkerNumber; |
564 |
|
|
565 |
|
/** |
566 |
< |
* Add delta (which may be negative) to both total and running |
234 |
< |
* count. This must be called upon creation and termination of |
235 |
< |
* worker threads. |
236 |
< |
* @param delta the number to add |
566 |
> |
* The index for the next created worker. Accessed under scanGuard. |
567 |
|
*/ |
568 |
< |
private void updateWorkerCount(int delta) { |
239 |
< |
int d = delta + (delta << 16); // add to both lo and hi parts |
240 |
< |
int s; |
241 |
< |
do;while (!casWorkerCounts(s = workerCounts, s + d)); |
242 |
< |
} |
568 |
> |
private int nextWorkerIndex; |
569 |
|
|
570 |
|
/** |
571 |
< |
* Lifecycle control. High word contains runState, low word |
572 |
< |
* contains the number of workers that are (probably) executing |
573 |
< |
* tasks. This value is atomically incremented before a worker |
574 |
< |
* gets a task to run, and decremented when worker has no tasks |
575 |
< |
* and cannot find any. These two fields are bundled together to |
576 |
< |
* support correct termination triggering. Note: activeCount |
577 |
< |
* CAS'es cheat by assuming active count is in low word, so need |
578 |
< |
* to be modified if this changes |
571 |
> |
* SeqLock and index masking for for updates to workers array. |
572 |
> |
* Locked when SG_UNIT is set. Unlocking clears bit by adding |
573 |
> |
* SG_UNIT. Staleness of read-only operations can be checked by |
574 |
> |
* comparing scanGuard to value before the reads. The low 16 bits |
575 |
> |
* (i.e, anding with SMASK) hold (the smallest power of two |
576 |
> |
* covering all worker indices, minus one, and is used to avoid |
577 |
> |
* dealing with large numbers of null slots when the workers array |
578 |
> |
* is overallocated. |
579 |
|
*/ |
580 |
< |
private volatile int runControl; |
580 |
> |
volatile int scanGuard; |
581 |
|
|
582 |
< |
// RunState values. Order among values matters |
257 |
< |
private static final int RUNNING = 0; |
258 |
< |
private static final int SHUTDOWN = 1; |
259 |
< |
private static final int TERMINATING = 2; |
260 |
< |
private static final int TERMINATED = 3; |
582 |
> |
private static final int SG_UNIT = 1 << 16; |
583 |
|
|
584 |
< |
private static int runStateOf(int c) { return c >>> 16; } |
585 |
< |
private static int activeCountOf(int c) { return c & shortMask; } |
586 |
< |
private static int runControlFor(int r, int a) { return (r << 16) + a; } |
584 |
> |
/** |
585 |
> |
* The wakeup interval (in nanoseconds) for a worker waiting for a |
586 |
> |
* task when the pool is quiescent to instead try to shrink the |
587 |
> |
* number of workers. The exact value does not matter too |
588 |
> |
* much. It must be short enough to release resources during |
589 |
> |
* sustained periods of idleness, but not so short that threads |
590 |
> |
* are continually re-created. |
591 |
> |
*/ |
592 |
> |
private static final long SHRINK_RATE = |
593 |
> |
4L * 1000L * 1000L * 1000L; // 4 seconds |
594 |
|
|
595 |
|
/** |
596 |
< |
* Increment active count. Called by workers before/during |
597 |
< |
* executing tasks. |
596 |
> |
* Top-level loop for worker threads: On each step: if the |
597 |
> |
* previous step swept through all queues and found no tasks, or |
598 |
> |
* there are excess threads, then possibly blocks. Otherwise, |
599 |
> |
* scans for and, if found, executes a task. Returns when pool |
600 |
> |
* and/or worker terminate. |
601 |
> |
* |
602 |
> |
* @param w the worker |
603 |
|
*/ |
604 |
< |
final void incrementActiveCount() { |
605 |
< |
int c; |
606 |
< |
do;while (!casRunControl(c = runControl, c+1)); |
604 |
> |
final void work(ForkJoinWorkerThread w) { |
605 |
> |
boolean swept = false; // true on empty scans |
606 |
> |
long c; |
607 |
> |
while (!w.terminate && (int)(c = ctl) >= 0) { |
608 |
> |
int a; // active count |
609 |
> |
if (!swept && (a = (int)(c >> AC_SHIFT)) <= 0) |
610 |
> |
swept = scan(w, a); |
611 |
> |
else if (tryAwaitWork(w, c)) |
612 |
> |
swept = false; |
613 |
> |
} |
614 |
> |
} |
615 |
> |
|
616 |
> |
// Signalling |
617 |
> |
|
618 |
> |
/** |
619 |
> |
* Wakes up or creates a worker. |
620 |
> |
*/ |
621 |
> |
final void signalWork() { |
622 |
> |
/* |
623 |
> |
* The while condition is true if: (there is are too few total |
624 |
> |
* workers OR there is at least one waiter) AND (there are too |
625 |
> |
* few active workers OR the pool is terminating). The value |
626 |
> |
* of e distinguishes the remaining cases: zero (no waiters) |
627 |
> |
* for create, negative if terminating (in which case do |
628 |
> |
* nothing), else release a waiter. The secondary checks for |
629 |
> |
* release (non-null array etc) can fail if the pool begins |
630 |
> |
* terminating after the test, and don't impose any added cost |
631 |
> |
* because JVMs must perform null and bounds checks anyway. |
632 |
> |
*/ |
633 |
> |
long c; int e, u; |
634 |
> |
while ((((e = (int)(c = ctl)) | (u = (int)(c >>> 32))) & |
635 |
> |
(INT_SIGN|SHORT_SIGN)) == (INT_SIGN|SHORT_SIGN) && e >= 0) { |
636 |
> |
if (e > 0) { // release a waiting worker |
637 |
> |
int i; ForkJoinWorkerThread w; ForkJoinWorkerThread[] ws; |
638 |
> |
if ((ws = workers) == null || |
639 |
> |
(i = ~e & SMASK) >= ws.length || |
640 |
> |
(w = ws[i]) == null) |
641 |
> |
break; |
642 |
> |
long nc = (((long)(w.nextWait & E_MASK)) | |
643 |
> |
((long)(u + UAC_UNIT) << 32)); |
644 |
> |
if (w.eventCount == e && |
645 |
> |
UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
646 |
> |
w.eventCount = (e + EC_UNIT) & E_MASK; |
647 |
> |
if (w.parked) |
648 |
> |
UNSAFE.unpark(w); |
649 |
> |
break; |
650 |
> |
} |
651 |
> |
} |
652 |
> |
else if (UNSAFE.compareAndSwapLong |
653 |
> |
(this, ctlOffset, c, |
654 |
> |
(long)(((u + UTC_UNIT) & UTC_MASK) | |
655 |
> |
((u + UAC_UNIT) & UAC_MASK)) << 32)) { |
656 |
> |
addWorker(); |
657 |
> |
break; |
658 |
> |
} |
659 |
> |
} |
660 |
|
} |
661 |
|
|
662 |
|
/** |
663 |
< |
* Decrement active count; possibly trigger termination. |
664 |
< |
* Called by workers when they can't find tasks. |
663 |
> |
* Variant of signalWork to help release waiters on rescans. |
664 |
> |
* Tries once to release a waiter if active count < 0. |
665 |
> |
* |
666 |
> |
* @return false if failed due to contention, else true |
667 |
|
*/ |
668 |
< |
final void decrementActiveCount() { |
669 |
< |
int c, nextc; |
670 |
< |
do;while (!casRunControl(c = runControl, nextc = c-1)); |
671 |
< |
if (canTerminateOnShutdown(nextc)) |
672 |
< |
terminateOnShutdown(); |
668 |
> |
private boolean tryReleaseWaiter() { |
669 |
> |
long c; int e, i; ForkJoinWorkerThread w; ForkJoinWorkerThread[] ws; |
670 |
> |
if ((e = (int)(c = ctl)) > 0 && |
671 |
> |
(int)(c >> AC_SHIFT) < 0 && |
672 |
> |
(ws = workers) != null && |
673 |
> |
(i = ~e & SMASK) < ws.length && |
674 |
> |
(w = ws[i]) != null) { |
675 |
> |
long nc = ((long)(w.nextWait & E_MASK) | |
676 |
> |
((c + AC_UNIT) & (AC_MASK|TC_MASK))); |
677 |
> |
if (w.eventCount != e || |
678 |
> |
!UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) |
679 |
> |
return false; |
680 |
> |
w.eventCount = (e + EC_UNIT) & E_MASK; |
681 |
> |
if (w.parked) |
682 |
> |
UNSAFE.unpark(w); |
683 |
> |
} |
684 |
> |
return true; |
685 |
> |
} |
686 |
> |
|
687 |
> |
// Scanning for tasks |
688 |
> |
|
689 |
> |
/** |
690 |
> |
* Scans for and, if found, executes one task. Scans start at a |
691 |
> |
* random index of workers array, and randomly select the first |
692 |
> |
* (2*#workers)-1 probes, and then, if all empty, resort to 2 |
693 |
> |
* circular sweeps, which is necessary to check quiescence. and |
694 |
> |
* taking a submission only if no stealable tasks were found. The |
695 |
> |
* steal code inside the loop is a specialized form of |
696 |
> |
* ForkJoinWorkerThread.deqTask, followed bookkeeping to support |
697 |
> |
* helpJoinTask and signal propagation. The code for submission |
698 |
> |
* queues is almost identical. On each steal, the worker completes |
699 |
> |
* not only the task, but also all local tasks that this task may |
700 |
> |
* have generated. On detecting staleness or contention when |
701 |
> |
* trying to take a task, this method returns without finishing |
702 |
> |
* sweep, which allows global state rechecks before retry. |
703 |
> |
* |
704 |
> |
* @param w the worker |
705 |
> |
* @param a the number of active workers |
706 |
> |
* @return true if swept all queues without finding a task |
707 |
> |
*/ |
708 |
> |
private boolean scan(ForkJoinWorkerThread w, int a) { |
709 |
> |
int g = scanGuard; // mask 0 avoids useless scans if only one active |
710 |
> |
int m = parallelism == 1 - a? 0 : g & SMASK; |
711 |
> |
ForkJoinWorkerThread[] ws = workers; |
712 |
> |
if (ws == null || ws.length <= m) // staleness check |
713 |
> |
return false; |
714 |
> |
for (int r = w.seed, k = r, j = -(m + m); j <= m + m; ++j) { |
715 |
> |
ForkJoinTask<?> t; ForkJoinTask<?>[] q; int b, i; |
716 |
> |
ForkJoinWorkerThread v = ws[k & m]; |
717 |
> |
if (v != null && (b = v.queueBase) != v.queueTop && |
718 |
> |
(q = v.queue) != null && (i = (q.length - 1) & b) >= 0) { |
719 |
> |
long u = (i << ASHIFT) + ABASE; |
720 |
> |
if ((t = q[i]) != null && v.queueBase == b && |
721 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
722 |
> |
int d = (v.queueBase = b + 1) - v.queueTop; |
723 |
> |
v.stealHint = w.poolIndex; |
724 |
> |
if (d != 0) |
725 |
> |
signalWork(); // propagate if nonempty |
726 |
> |
w.execTask(t); |
727 |
> |
} |
728 |
> |
r ^= r << 13; r ^= r >>> 17; w.seed = r ^ (r << 5); |
729 |
> |
return false; // store next seed |
730 |
> |
} |
731 |
> |
else if (j < 0) { // xorshift |
732 |
> |
r ^= r << 13; r ^= r >>> 17; k = r ^= r << 5; |
733 |
> |
} |
734 |
> |
else |
735 |
> |
++k; |
736 |
> |
} |
737 |
> |
if (scanGuard != g) // staleness check |
738 |
> |
return false; |
739 |
> |
else { // try to take submission |
740 |
> |
ForkJoinTask<?> t; ForkJoinTask<?>[] q; int b, i; |
741 |
> |
if ((b = queueBase) != queueTop && |
742 |
> |
(q = submissionQueue) != null && |
743 |
> |
(i = (q.length - 1) & b) >= 0) { |
744 |
> |
long u = (i << ASHIFT) + ABASE; |
745 |
> |
if ((t = q[i]) != null && queueBase == b && |
746 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
747 |
> |
queueBase = b + 1; |
748 |
> |
w.execTask(t); |
749 |
> |
} |
750 |
> |
return false; |
751 |
> |
} |
752 |
> |
return true; // all queues empty |
753 |
> |
} |
754 |
|
} |
755 |
|
|
756 |
|
/** |
757 |
< |
* Return true if argument represents zero active count and |
758 |
< |
* nonzero runstate, which is the triggering condition for |
759 |
< |
* terminating on shutdown. |
760 |
< |
*/ |
761 |
< |
private static boolean canTerminateOnShutdown(int c) { |
762 |
< |
return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit |
757 |
> |
* Tries to enqueue worker in wait queue and await change in |
758 |
> |
* worker's eventCount. Before blocking, rescans queues to avoid |
759 |
> |
* missed signals. If the pool is quiescent, possibly terminates |
760 |
> |
* worker upon exit. |
761 |
> |
* |
762 |
> |
* @param w the calling worker |
763 |
> |
* @param c the ctl value on entry |
764 |
> |
* @return true if waited or another thread was released upon enq |
765 |
> |
*/ |
766 |
> |
private boolean tryAwaitWork(ForkJoinWorkerThread w, long c) { |
767 |
> |
int v = w.eventCount; |
768 |
> |
w.nextWait = (int)c; // w's successor record |
769 |
> |
long nc = (long)(v & E_MASK) | ((c - AC_UNIT) & (AC_MASK|TC_MASK)); |
770 |
> |
if (ctl != c || !UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
771 |
> |
long d = ctl; // return true if lost to a deq, to force rescan |
772 |
> |
return (int)d != (int)c && ((d - c) & AC_MASK) >= 0L; |
773 |
> |
} |
774 |
> |
if (parallelism + (int)(c >> AC_SHIFT) == 1 && |
775 |
> |
blockedCount == 0 && quiescerCount == 0) |
776 |
> |
idleAwaitWork(w, v); // quiescent -- maybe shrink |
777 |
> |
|
778 |
> |
boolean rescanned = false; |
779 |
> |
for (int sc;;) { |
780 |
> |
if (w.eventCount != v) |
781 |
> |
return true; |
782 |
> |
if ((sc = w.stealCount) != 0) { |
783 |
> |
long s = stealCount; // accumulate stealCount |
784 |
> |
if (UNSAFE.compareAndSwapLong(this, stealCountOffset, s, s+sc)) |
785 |
> |
w.stealCount = 0; |
786 |
> |
} |
787 |
> |
else if (!rescanned) { |
788 |
> |
int g = scanGuard, m = g & SMASK; |
789 |
> |
ForkJoinWorkerThread[] ws = workers; |
790 |
> |
if (ws != null && m < ws.length) { |
791 |
> |
rescanned = true; |
792 |
> |
for (int i = 0; i <= m; ++i) { |
793 |
> |
ForkJoinWorkerThread u = ws[i]; |
794 |
> |
if (u != null) { |
795 |
> |
if (u.queueBase != u.queueTop && |
796 |
> |
!tryReleaseWaiter()) |
797 |
> |
rescanned = false; // contended |
798 |
> |
if (w.eventCount != v) |
799 |
> |
return true; |
800 |
> |
} |
801 |
> |
} |
802 |
> |
} |
803 |
> |
if (scanGuard != g || // stale |
804 |
> |
(queueBase != queueTop && !tryReleaseWaiter())) |
805 |
> |
rescanned = false; |
806 |
> |
if (!rescanned) |
807 |
> |
Thread.yield(); // reduce contention |
808 |
> |
else |
809 |
> |
Thread.interrupted(); // clear before park |
810 |
> |
} |
811 |
> |
else { |
812 |
> |
w.parked = true; // must recheck |
813 |
> |
if (w.eventCount != v) { |
814 |
> |
w.parked = false; |
815 |
> |
return true; |
816 |
> |
} |
817 |
> |
LockSupport.park(this); |
818 |
> |
rescanned = w.parked = false; |
819 |
> |
} |
820 |
> |
} |
821 |
|
} |
822 |
|
|
823 |
|
/** |
824 |
< |
* Transition run state to at least the given state. Return true |
825 |
< |
* if not already at least given state. |
824 |
> |
* If pool is quiescent, checks for termination, and waits for |
825 |
> |
* event signal for up to SHRINK_RATE nanosecs. On timeout, if ctl |
826 |
> |
* has not changed, terminates the worker. Upon its termination |
827 |
> |
* (see deregisterWorker), it may wake up another worker to |
828 |
> |
* possibly repeat this process. |
829 |
> |
* |
830 |
> |
* @param w the calling worker |
831 |
> |
* @param v the eventCount w must wait until changed |
832 |
|
*/ |
833 |
< |
private boolean transitionRunStateTo(int state) { |
834 |
< |
for (;;) { |
835 |
< |
int c = runControl; |
836 |
< |
if (runStateOf(c) >= state) |
837 |
< |
return false; |
838 |
< |
if (casRunControl(c, runControlFor(state, activeCountOf(c)))) |
839 |
< |
return true; |
833 |
> |
private void idleAwaitWork(ForkJoinWorkerThread w, int v) { |
834 |
> |
ForkJoinTask.helpExpungeStaleExceptions(); // help clean weak refs |
835 |
> |
if (shutdown) |
836 |
> |
tryTerminate(false); |
837 |
> |
long c = ctl; |
838 |
> |
long nc = (((c & (AC_MASK|TC_MASK)) + AC_UNIT) | |
839 |
> |
(long)(w.nextWait & E_MASK)); // ctl value to release w |
840 |
> |
if (w.eventCount == v && |
841 |
> |
parallelism + (int)(c >> AC_SHIFT) == 0 && |
842 |
> |
blockedCount == 0 && quiescerCount == 0) { |
843 |
> |
long startTime = System.nanoTime(); |
844 |
> |
Thread.interrupted(); |
845 |
> |
if (w.eventCount == v) { |
846 |
> |
w.parked = true; |
847 |
> |
if (w.eventCount == v) |
848 |
> |
LockSupport.parkNanos(this, SHRINK_RATE); |
849 |
> |
w.parked = false; |
850 |
> |
if (w.eventCount == v && ctl == c && |
851 |
> |
System.nanoTime() - startTime >= SHRINK_RATE && |
852 |
> |
UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
853 |
> |
w.terminate = true; |
854 |
> |
w.eventCount = ((int)c + EC_UNIT) & E_MASK; |
855 |
> |
} |
856 |
> |
} |
857 |
|
} |
858 |
|
} |
859 |
|
|
860 |
+ |
// Submissions |
861 |
+ |
|
862 |
|
/** |
863 |
< |
* Controls whether to add spares to maintain parallelism |
863 |
> |
* Enqueues the given task in the submissionQueue. Same idea as |
864 |
> |
* ForkJoinWorkerThread.pushTask except for use of submissionLock. |
865 |
> |
* |
866 |
> |
* @param t the task |
867 |
|
*/ |
868 |
< |
private volatile boolean maintainsParallelism; |
868 |
> |
private void addSubmission(ForkJoinTask<?> t) { |
869 |
> |
final ReentrantLock lock = this.submissionLock; |
870 |
> |
lock.lock(); |
871 |
> |
try { |
872 |
> |
ForkJoinTask<?>[] q; int s, m; |
873 |
> |
if ((q = submissionQueue) != null) { // ignore if queue removed |
874 |
> |
long u = (((s = queueTop) & (m = q.length-1)) << ASHIFT)+ABASE; |
875 |
> |
UNSAFE.putOrderedObject(q, u, t); |
876 |
> |
queueTop = s + 1; |
877 |
> |
if (s - queueBase == m) |
878 |
> |
growSubmissionQueue(); |
879 |
> |
} |
880 |
> |
} finally { |
881 |
> |
lock.unlock(); |
882 |
> |
} |
883 |
> |
signalWork(); |
884 |
> |
} |
885 |
|
|
886 |
< |
// Constructors |
886 |
> |
// (pollSubmission is defined below with exported methods) |
887 |
|
|
888 |
|
/** |
889 |
< |
* Creates a ForkJoinPool with a pool size equal to the number of |
890 |
< |
* processors available on the system and using the default |
319 |
< |
* ForkJoinWorkerThreadFactory, |
320 |
< |
* @throws SecurityException if a security manager exists and |
321 |
< |
* the caller is not permitted to modify threads |
322 |
< |
* because it does not hold {@link |
323 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
889 |
> |
* Creates or doubles submissionQueue array. |
890 |
> |
* Basically identical to ForkJoinWorkerThread version |
891 |
|
*/ |
892 |
< |
public ForkJoinPool() { |
893 |
< |
this(Runtime.getRuntime().availableProcessors(), |
894 |
< |
defaultForkJoinWorkerThreadFactory); |
892 |
> |
private void growSubmissionQueue() { |
893 |
> |
ForkJoinTask<?>[] oldQ = submissionQueue; |
894 |
> |
int size = oldQ != null ? oldQ.length << 1 : INITIAL_QUEUE_CAPACITY; |
895 |
> |
if (size > MAXIMUM_QUEUE_CAPACITY) |
896 |
> |
throw new RejectedExecutionException("Queue capacity exceeded"); |
897 |
> |
if (size < INITIAL_QUEUE_CAPACITY) |
898 |
> |
size = INITIAL_QUEUE_CAPACITY; |
899 |
> |
ForkJoinTask<?>[] q = submissionQueue = new ForkJoinTask<?>[size]; |
900 |
> |
int mask = size - 1; |
901 |
> |
int top = queueTop; |
902 |
> |
int oldMask; |
903 |
> |
if (oldQ != null && (oldMask = oldQ.length - 1) >= 0) { |
904 |
> |
for (int b = queueBase; b != top; ++b) { |
905 |
> |
long u = ((b & oldMask) << ASHIFT) + ABASE; |
906 |
> |
Object x = UNSAFE.getObjectVolatile(oldQ, u); |
907 |
> |
if (x != null && UNSAFE.compareAndSwapObject(oldQ, u, x, null)) |
908 |
> |
UNSAFE.putObjectVolatile |
909 |
> |
(q, ((b & mask) << ASHIFT) + ABASE, x); |
910 |
> |
} |
911 |
> |
} |
912 |
|
} |
913 |
|
|
914 |
+ |
// Blocking support |
915 |
+ |
|
916 |
|
/** |
917 |
< |
* Creates a ForkJoinPool with the indicated parellelism level |
918 |
< |
* threads, and using the default ForkJoinWorkerThreadFactory, |
919 |
< |
* @param parallelism the number of worker threads |
920 |
< |
* @throws IllegalArgumentException if parallelism less than or |
921 |
< |
* equal to zero |
922 |
< |
* @throws SecurityException if a security manager exists and |
337 |
< |
* the caller is not permitted to modify threads |
338 |
< |
* because it does not hold {@link |
339 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
917 |
> |
* Tries to increment blockedCount, decrement active count |
918 |
> |
* (sometimes implicitly) and possibly release or create a |
919 |
> |
* compensating worker in preparation for blocking. Fails |
920 |
> |
* on contention or termination. |
921 |
> |
* |
922 |
> |
* @return true if the caller can block, else should recheck and retry |
923 |
|
*/ |
924 |
< |
public ForkJoinPool(int parallelism) { |
925 |
< |
this(parallelism, defaultForkJoinWorkerThreadFactory); |
924 |
> |
private boolean tryPreBlock() { |
925 |
> |
int b = blockedCount; |
926 |
> |
if (UNSAFE.compareAndSwapInt(this, blockedCountOffset, b, b + 1)) { |
927 |
> |
int pc = parallelism; |
928 |
> |
do { |
929 |
> |
ForkJoinWorkerThread[] ws; ForkJoinWorkerThread w; |
930 |
> |
int e, ac, tc, rc, i; |
931 |
> |
long c = ctl; |
932 |
> |
int u = (int)(c >>> 32); |
933 |
> |
if ((e = (int)c) < 0) { |
934 |
> |
// skip -- terminating |
935 |
> |
} |
936 |
> |
else if ((ac = (u >> UAC_SHIFT)) <= 0 && e != 0 && |
937 |
> |
(ws = workers) != null && |
938 |
> |
(i = ~e & SMASK) < ws.length && |
939 |
> |
(w = ws[i]) != null) { |
940 |
> |
long nc = ((long)(w.nextWait & E_MASK) | |
941 |
> |
(c & (AC_MASK|TC_MASK))); |
942 |
> |
if (w.eventCount == e && |
943 |
> |
UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
944 |
> |
w.eventCount = (e + EC_UNIT) & E_MASK; |
945 |
> |
if (w.parked) |
946 |
> |
UNSAFE.unpark(w); |
947 |
> |
return true; // release an idle worker |
948 |
> |
} |
949 |
> |
} |
950 |
> |
else if ((tc = (short)(u >>> UTC_SHIFT)) >= 0 && ac + pc > 1) { |
951 |
> |
long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK); |
952 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) |
953 |
> |
return true; // no compensation needed |
954 |
> |
} |
955 |
> |
else if (tc + pc < MAX_ID) { |
956 |
> |
long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK); |
957 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, nc)) { |
958 |
> |
addWorker(); |
959 |
> |
return true; // create a replacement |
960 |
> |
} |
961 |
> |
} |
962 |
> |
// try to back out on any failure and let caller retry |
963 |
> |
} while (!UNSAFE.compareAndSwapInt(this, blockedCountOffset, |
964 |
> |
b = blockedCount, b - 1)); |
965 |
> |
} |
966 |
> |
return false; |
967 |
|
} |
968 |
|
|
969 |
|
/** |
970 |
< |
* Creates a ForkJoinPool with parallelism equal to the number of |
347 |
< |
* processors available on the system and using the given |
348 |
< |
* ForkJoinWorkerThreadFactory, |
349 |
< |
* @param factory the factory for creating new threads |
350 |
< |
* @throws NullPointerException if factory is null |
351 |
< |
* @throws SecurityException if a security manager exists and |
352 |
< |
* the caller is not permitted to modify threads |
353 |
< |
* because it does not hold {@link |
354 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
970 |
> |
* Decrements blockedCount and increments active count |
971 |
|
*/ |
972 |
< |
public ForkJoinPool(ForkJoinWorkerThreadFactory factory) { |
973 |
< |
this(Runtime.getRuntime().availableProcessors(), factory); |
972 |
> |
private void postBlock() { |
973 |
> |
long c; |
974 |
> |
do {} while (!UNSAFE.compareAndSwapLong(this, ctlOffset, // no mask |
975 |
> |
c = ctl, c + AC_UNIT)); |
976 |
> |
int b; |
977 |
> |
do {} while(!UNSAFE.compareAndSwapInt(this, blockedCountOffset, |
978 |
> |
b = blockedCount, b - 1)); |
979 |
|
} |
980 |
|
|
981 |
|
/** |
982 |
< |
* Creates a ForkJoinPool with the given parallelism and factory. |
982 |
> |
* Possibly blocks waiting for the given task to complete, or |
983 |
> |
* cancels the task if terminating. Fails to wait if contended. |
984 |
|
* |
985 |
< |
* @param parallelism the targeted number of worker threads |
364 |
< |
* @param factory the factory for creating new threads |
365 |
< |
* @throws IllegalArgumentException if parallelism less than or |
366 |
< |
* equal to zero, or greater than implementation limit. |
367 |
< |
* @throws NullPointerException if factory is null |
368 |
< |
* @throws SecurityException if a security manager exists and |
369 |
< |
* the caller is not permitted to modify threads |
370 |
< |
* because it does not hold {@link |
371 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
985 |
> |
* @param joinMe the task |
986 |
|
*/ |
987 |
< |
public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) { |
988 |
< |
if (parallelism <= 0 || parallelism > MAX_THREADS) |
989 |
< |
throw new IllegalArgumentException(); |
990 |
< |
if (factory == null) |
991 |
< |
throw new NullPointerException(); |
992 |
< |
checkPermission(); |
993 |
< |
this.factory = factory; |
994 |
< |
this.parallelism = parallelism; |
995 |
< |
this.maxPoolSize = MAX_THREADS; |
996 |
< |
this.maintainsParallelism = true; |
997 |
< |
this.poolNumber = poolNumberGenerator.incrementAndGet(); |
384 |
< |
this.workerLock = new ReentrantLock(); |
385 |
< |
this.termination = workerLock.newCondition(); |
386 |
< |
this.stealCount = new AtomicLong(); |
387 |
< |
this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>(); |
388 |
< |
createAndStartInitialWorkers(parallelism); |
987 |
> |
final void tryAwaitJoin(ForkJoinTask<?> joinMe) { |
988 |
> |
int s; |
989 |
> |
Thread.interrupted(); // clear interrupts before checking termination |
990 |
> |
if (joinMe.status >= 0) { |
991 |
> |
if (tryPreBlock()) { |
992 |
> |
joinMe.tryAwaitDone(0L); |
993 |
> |
postBlock(); |
994 |
> |
} |
995 |
> |
if ((ctl & STOP_BIT) != 0L) |
996 |
> |
joinMe.cancelIgnoringExceptions(); |
997 |
> |
} |
998 |
|
} |
999 |
|
|
1000 |
|
/** |
1001 |
< |
* Create new worker using factory. |
1002 |
< |
* @param index the index to assign worker |
1003 |
< |
* @return new worker, or null of factory failed |
1001 |
> |
* Possibly blocks the given worker waiting for joinMe to |
1002 |
> |
* complete or timeout |
1003 |
> |
* |
1004 |
> |
* @param joinMe the task |
1005 |
> |
* @param millis the wait time for underlying Object.wait |
1006 |
|
*/ |
1007 |
< |
private ForkJoinWorkerThread createWorker(int index) { |
1008 |
< |
Thread.UncaughtExceptionHandler h = ueh; |
1009 |
< |
ForkJoinWorkerThread w = factory.newThread(this); |
1010 |
< |
if (w != null) { |
1011 |
< |
w.poolIndex = index; |
1012 |
< |
w.setDaemon(true); |
1013 |
< |
w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index); |
1014 |
< |
if (h != null) |
1015 |
< |
w.setUncaughtExceptionHandler(h); |
1007 |
> |
final void timedAwaitJoin(ForkJoinTask<?> joinMe, long nanos) { |
1008 |
> |
while (joinMe.status >= 0) { |
1009 |
> |
Thread.interrupted(); |
1010 |
> |
if ((ctl & STOP_BIT) != 0L) { |
1011 |
> |
joinMe.cancelIgnoringExceptions(); |
1012 |
> |
break; |
1013 |
> |
} |
1014 |
> |
if (tryPreBlock()) { |
1015 |
> |
long last = System.nanoTime(); |
1016 |
> |
while (joinMe.status >= 0) { |
1017 |
> |
long millis = TimeUnit.NANOSECONDS.toMillis(nanos); |
1018 |
> |
if (millis <= 0) |
1019 |
> |
break; |
1020 |
> |
joinMe.tryAwaitDone(millis); |
1021 |
> |
if (joinMe.status < 0) |
1022 |
> |
break; |
1023 |
> |
if ((ctl & STOP_BIT) != 0L) { |
1024 |
> |
joinMe.cancelIgnoringExceptions(); |
1025 |
> |
break; |
1026 |
> |
} |
1027 |
> |
long now = System.nanoTime(); |
1028 |
> |
nanos -= now - last; |
1029 |
> |
last = now; |
1030 |
> |
} |
1031 |
> |
postBlock(); |
1032 |
> |
break; |
1033 |
> |
} |
1034 |
|
} |
406 |
– |
return w; |
1035 |
|
} |
1036 |
|
|
1037 |
|
/** |
1038 |
< |
* Return a good size for worker array given pool size. |
411 |
< |
* Currently requires size to be a power of two. |
1038 |
> |
* If necessary, compensates for blocker, and blocks |
1039 |
|
*/ |
1040 |
< |
private static int arraySizeFor(int ps) { |
1041 |
< |
return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1))); |
1040 |
> |
private void awaitBlocker(ManagedBlocker blocker) |
1041 |
> |
throws InterruptedException { |
1042 |
> |
while (!blocker.isReleasable()) { |
1043 |
> |
if (tryPreBlock()) { |
1044 |
> |
try { |
1045 |
> |
do {} while (!blocker.isReleasable() && !blocker.block()); |
1046 |
> |
} finally { |
1047 |
> |
postBlock(); |
1048 |
> |
} |
1049 |
> |
break; |
1050 |
> |
} |
1051 |
> |
} |
1052 |
|
} |
1053 |
|
|
1054 |
+ |
// Creating, registering and deregistring workers |
1055 |
+ |
|
1056 |
|
/** |
1057 |
< |
* Create or resize array if necessary to hold newLength |
1058 |
< |
* @return the array |
1057 |
> |
* Tries to create and start a worker; minimally rolls back counts |
1058 |
> |
* on failure. |
1059 |
|
*/ |
1060 |
< |
private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) { |
1061 |
< |
ForkJoinWorkerThread[] ws = workers; |
1062 |
< |
if (ws == null) |
1063 |
< |
return workers = new ForkJoinWorkerThread[arraySizeFor(newLength)]; |
1064 |
< |
else if (newLength > ws.length) |
1065 |
< |
return workers = Arrays.copyOf(ws, arraySizeFor(newLength)); |
1060 |
> |
private void addWorker() { |
1061 |
> |
Throwable ex = null; |
1062 |
> |
ForkJoinWorkerThread t = null; |
1063 |
> |
try { |
1064 |
> |
t = factory.newThread(this); |
1065 |
> |
} catch (Throwable e) { |
1066 |
> |
ex = e; |
1067 |
> |
} |
1068 |
> |
if (t == null) { // null or exceptional factory return |
1069 |
> |
long c; // adjust counts |
1070 |
> |
do {} while (!UNSAFE.compareAndSwapLong |
1071 |
> |
(this, ctlOffset, c = ctl, |
1072 |
> |
(((c - AC_UNIT) & AC_MASK) | |
1073 |
> |
((c - TC_UNIT) & TC_MASK) | |
1074 |
> |
(c & ~(AC_MASK|TC_MASK))))); |
1075 |
> |
// Propagate exception if originating from an external caller |
1076 |
> |
if (!tryTerminate(false) && ex != null && |
1077 |
> |
!(Thread.currentThread() instanceof ForkJoinWorkerThread)) |
1078 |
> |
UNSAFE.throwException(ex); |
1079 |
> |
} |
1080 |
|
else |
1081 |
< |
return ws; |
1081 |
> |
t.start(); |
1082 |
|
} |
1083 |
|
|
1084 |
|
/** |
1085 |
< |
* Try to shrink workers into smaller array after one or more terminate |
1085 |
> |
* Callback from ForkJoinWorkerThread constructor to assign a |
1086 |
> |
* public name |
1087 |
|
*/ |
1088 |
< |
private void tryShrinkWorkerArray() { |
1089 |
< |
ForkJoinWorkerThread[] ws = workers; |
1090 |
< |
int len = ws.length; |
1091 |
< |
int last = len - 1; |
1092 |
< |
while (last >= 0 && ws[last] == null) |
1093 |
< |
--last; |
440 |
< |
int newLength = arraySizeFor(last+1); |
441 |
< |
if (newLength < len) |
442 |
< |
workers = Arrays.copyOf(ws, newLength); |
1088 |
> |
final String nextWorkerName() { |
1089 |
> |
for (int n;;) { |
1090 |
> |
if (UNSAFE.compareAndSwapInt(this, nextWorkerNumberOffset, |
1091 |
> |
n = nextWorkerNumber, ++n)) |
1092 |
> |
return workerNamePrefix + n; |
1093 |
> |
} |
1094 |
|
} |
1095 |
|
|
1096 |
|
/** |
1097 |
< |
* Initial worker array and worker creation and startup. (This |
1098 |
< |
* must be done under lock to avoid interference by some of the |
1099 |
< |
* newly started threads while creating others.) |
1097 |
> |
* Callback from ForkJoinWorkerThread constructor to |
1098 |
> |
* determine its poolIndex and record in workers array. |
1099 |
> |
* |
1100 |
> |
* @param w the worker |
1101 |
> |
* @return the worker's pool index |
1102 |
|
*/ |
1103 |
< |
private void createAndStartInitialWorkers(int ps) { |
1104 |
< |
final ReentrantLock lock = this.workerLock; |
1105 |
< |
lock.lock(); |
1106 |
< |
try { |
1107 |
< |
ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps); |
1108 |
< |
for (int i = 0; i < ps; ++i) { |
1109 |
< |
ForkJoinWorkerThread w = createWorker(i); |
1110 |
< |
if (w != null) { |
1111 |
< |
ws[i] = w; |
1112 |
< |
w.start(); |
1113 |
< |
updateWorkerCount(1); |
1103 |
> |
final int registerWorker(ForkJoinWorkerThread w) { |
1104 |
> |
/* |
1105 |
> |
* In the typical case, a new worker acquires the lock, uses |
1106 |
> |
* next available index and returns quickly. Since we should |
1107 |
> |
* not block callers (ultimately from signalWork or |
1108 |
> |
* tryPreBlock) waiting for the lock needed to do this, we |
1109 |
> |
* instead help release other workers while waiting for the |
1110 |
> |
* lock. |
1111 |
> |
*/ |
1112 |
> |
for (int g;;) { |
1113 |
> |
ForkJoinWorkerThread[] ws; |
1114 |
> |
if (((g = scanGuard) & SG_UNIT) == 0 && |
1115 |
> |
UNSAFE.compareAndSwapInt(this, scanGuardOffset, |
1116 |
> |
g, g | SG_UNIT)) { |
1117 |
> |
int k = nextWorkerIndex; |
1118 |
> |
try { |
1119 |
> |
if ((ws = workers) != null) { // ignore on shutdown |
1120 |
> |
int n = ws.length; |
1121 |
> |
if (k < 0 || k >= n || ws[k] != null) { |
1122 |
> |
for (k = 0; k < n && ws[k] != null; ++k) |
1123 |
> |
; |
1124 |
> |
if (k == n) |
1125 |
> |
ws = workers = Arrays.copyOf(ws, n << 1); |
1126 |
> |
} |
1127 |
> |
ws[k] = w; |
1128 |
> |
nextWorkerIndex = k + 1; |
1129 |
> |
int m = g & SMASK; |
1130 |
> |
g = k >= m? ((m << 1) + 1) & SMASK : g + (SG_UNIT<<1); |
1131 |
> |
} |
1132 |
> |
} finally { |
1133 |
> |
scanGuard = g; |
1134 |
|
} |
1135 |
+ |
return k; |
1136 |
|
} |
1137 |
< |
} finally { |
1138 |
< |
lock.unlock(); |
1137 |
> |
else if ((ws = workers) != null) { // help release others |
1138 |
> |
for (ForkJoinWorkerThread u : ws) { |
1139 |
> |
if (u != null && u.queueBase != u.queueTop) { |
1140 |
> |
if (tryReleaseWaiter()) |
1141 |
> |
break; |
1142 |
> |
} |
1143 |
> |
} |
1144 |
> |
} |
1145 |
> |
} |
1146 |
> |
} |
1147 |
> |
|
1148 |
> |
/** |
1149 |
> |
* Final callback from terminating worker. Removes record of |
1150 |
> |
* worker from array, and adjusts counts. If pool is shutting |
1151 |
> |
* down, tries to complete termination. |
1152 |
> |
* |
1153 |
> |
* @param w the worker |
1154 |
> |
*/ |
1155 |
> |
final void deregisterWorker(ForkJoinWorkerThread w, Throwable ex) { |
1156 |
> |
int idx = w.poolIndex; |
1157 |
> |
int sc = w.stealCount; |
1158 |
> |
int steps = 0; |
1159 |
> |
// Remove from array, adjust worker counts and collect steal count. |
1160 |
> |
// We can intermix failed removes or adjusts with steal updates |
1161 |
> |
do { |
1162 |
> |
long s, c; |
1163 |
> |
int g; |
1164 |
> |
if (steps == 0 && ((g = scanGuard) & SG_UNIT) == 0 && |
1165 |
> |
UNSAFE.compareAndSwapInt(this, scanGuardOffset, |
1166 |
> |
g, g |= SG_UNIT)) { |
1167 |
> |
ForkJoinWorkerThread[] ws = workers; |
1168 |
> |
if (ws != null && idx >= 0 && |
1169 |
> |
idx < ws.length && ws[idx] == w) |
1170 |
> |
ws[idx] = null; // verify |
1171 |
> |
nextWorkerIndex = idx; |
1172 |
> |
scanGuard = g + SG_UNIT; |
1173 |
> |
steps = 1; |
1174 |
> |
} |
1175 |
> |
if (steps == 1 && |
1176 |
> |
UNSAFE.compareAndSwapLong(this, ctlOffset, c = ctl, |
1177 |
> |
(((c - AC_UNIT) & AC_MASK) | |
1178 |
> |
((c - TC_UNIT) & TC_MASK) | |
1179 |
> |
(c & ~(AC_MASK|TC_MASK))))) |
1180 |
> |
steps = 2; |
1181 |
> |
if (sc != 0 && |
1182 |
> |
UNSAFE.compareAndSwapLong(this, stealCountOffset, |
1183 |
> |
s = stealCount, s + sc)) |
1184 |
> |
sc = 0; |
1185 |
> |
} while (steps != 2 || sc != 0); |
1186 |
> |
if (!tryTerminate(false)) { |
1187 |
> |
if (ex != null) // possibly replace if died abnormally |
1188 |
> |
signalWork(); |
1189 |
> |
else |
1190 |
> |
tryReleaseWaiter(); |
1191 |
|
} |
1192 |
|
} |
1193 |
|
|
1194 |
+ |
// Shutdown and termination |
1195 |
+ |
|
1196 |
|
/** |
1197 |
< |
* Worker creation and startup for threads added via setParallelism. |
1197 |
> |
* Possibly initiates and/or completes termination. |
1198 |
> |
* |
1199 |
> |
* @param now if true, unconditionally terminate, else only |
1200 |
> |
* if shutdown and empty queue and no active workers |
1201 |
> |
* @return true if now terminating or terminated |
1202 |
|
*/ |
1203 |
< |
private void createAndStartAddedWorkers() { |
1204 |
< |
resumeAllSpares(); // Allow spares to convert to nonspare |
1205 |
< |
int ps = parallelism; |
1206 |
< |
ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps); |
1207 |
< |
int len = ws.length; |
1208 |
< |
// Sweep through slots, to keep lowest indices most populated |
1209 |
< |
int k = 0; |
1210 |
< |
while (k < len) { |
1211 |
< |
if (ws[k] != null) { |
1212 |
< |
++k; |
1213 |
< |
continue; |
1203 |
> |
private boolean tryTerminate(boolean now) { |
1204 |
> |
long c; |
1205 |
> |
while (((c = ctl) & STOP_BIT) == 0) { |
1206 |
> |
if (!now) { |
1207 |
> |
if ((int)(c >> AC_SHIFT) != -parallelism) |
1208 |
> |
return false; |
1209 |
> |
if (!shutdown || blockedCount != 0 || quiescerCount != 0 || |
1210 |
> |
queueTop - queueBase > 0) { |
1211 |
> |
if (ctl == c) // staleness check |
1212 |
> |
return false; |
1213 |
> |
continue; |
1214 |
> |
} |
1215 |
|
} |
1216 |
< |
int s = workerCounts; |
1217 |
< |
int tc = totalCountOf(s); |
1218 |
< |
int rc = runningCountOf(s); |
1219 |
< |
if (rc >= ps || tc >= ps) |
1220 |
< |
break; |
1221 |
< |
if (casWorkerCounts (s, workerCountsFor(tc+1, rc+1))) { |
1222 |
< |
ForkJoinWorkerThread w = createWorker(k); |
1223 |
< |
if (w != null) { |
1224 |
< |
ws[k++] = w; |
1225 |
< |
w.start(); |
1216 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, c | STOP_BIT)) |
1217 |
> |
startTerminating(); |
1218 |
> |
} |
1219 |
> |
if ((short)(c >>> TC_SHIFT) == -parallelism) { |
1220 |
> |
submissionLock.lock(); |
1221 |
> |
termination.signalAll(); |
1222 |
> |
submissionLock.unlock(); |
1223 |
> |
} |
1224 |
> |
return true; |
1225 |
> |
} |
1226 |
> |
|
1227 |
> |
/** |
1228 |
> |
* Runs up to three passes through workers: (0) Setting |
1229 |
> |
* termination status for each worker, followed by wakeups up |
1230 |
> |
* queued workers (1) helping cancel tasks (2) interrupting |
1231 |
> |
* lagging threads (likely in external tasks, but possibly also |
1232 |
> |
* blocked in joins). Each pass repeats previous steps because of |
1233 |
> |
* potential lagging thread creation. |
1234 |
> |
*/ |
1235 |
> |
private void startTerminating() { |
1236 |
> |
cancelSubmissions(); |
1237 |
> |
for (int pass = 0; pass < 3; ++pass) { |
1238 |
> |
ForkJoinWorkerThread[] ws = workers; |
1239 |
> |
if (ws != null) { |
1240 |
> |
for (ForkJoinWorkerThread w : ws) { |
1241 |
> |
if (w != null) { |
1242 |
> |
w.terminate = true; |
1243 |
> |
if (pass > 0) { |
1244 |
> |
w.cancelTasks(); |
1245 |
> |
if (pass > 1 && !w.isInterrupted()) { |
1246 |
> |
try { |
1247 |
> |
w.interrupt(); |
1248 |
> |
} catch (SecurityException ignore) { |
1249 |
> |
} |
1250 |
> |
} |
1251 |
> |
} |
1252 |
> |
} |
1253 |
|
} |
1254 |
< |
else { |
1255 |
< |
updateWorkerCount(-1); // back out on failed creation |
1256 |
< |
break; |
1254 |
> |
terminateWaiters(); |
1255 |
> |
} |
1256 |
> |
} |
1257 |
> |
} |
1258 |
> |
|
1259 |
> |
/** |
1260 |
> |
* Polls and cancels all submissions. Called only during termination. |
1261 |
> |
*/ |
1262 |
> |
private void cancelSubmissions() { |
1263 |
> |
while (queueBase != queueTop) { |
1264 |
> |
ForkJoinTask<?> task = pollSubmission(); |
1265 |
> |
if (task != null) { |
1266 |
> |
try { |
1267 |
> |
task.cancel(false); |
1268 |
> |
} catch (Throwable ignore) { |
1269 |
|
} |
1270 |
|
} |
1271 |
|
} |
1272 |
|
} |
1273 |
|
|
1274 |
< |
// Execution methods |
1274 |
> |
/** |
1275 |
> |
* Tries to set the termination status of waiting workers, and |
1276 |
> |
* then wake them up (after which they will terminate). |
1277 |
> |
*/ |
1278 |
> |
private void terminateWaiters() { |
1279 |
> |
ForkJoinWorkerThread[] ws = workers; |
1280 |
> |
if (ws != null) { |
1281 |
> |
ForkJoinWorkerThread w; long c; int i, e; |
1282 |
> |
int n = ws.length; |
1283 |
> |
while ((i = ~(e = (int)(c = ctl)) & SMASK) < n && |
1284 |
> |
(w = ws[i]) != null && w.eventCount == (e & E_MASK)) { |
1285 |
> |
if (UNSAFE.compareAndSwapLong(this, ctlOffset, c, |
1286 |
> |
(long)(w.nextWait & E_MASK) | |
1287 |
> |
((c + AC_UNIT) & AC_MASK) | |
1288 |
> |
(c & (TC_MASK|STOP_BIT)))) { |
1289 |
> |
w.terminate = true; |
1290 |
> |
w.eventCount = e + EC_UNIT; |
1291 |
> |
if (w.parked) |
1292 |
> |
UNSAFE.unpark(w); |
1293 |
> |
} |
1294 |
> |
} |
1295 |
> |
} |
1296 |
> |
} |
1297 |
> |
|
1298 |
> |
// misc ForkJoinWorkerThread support |
1299 |
|
|
1300 |
|
/** |
1301 |
< |
* Common code for execute, invoke and submit |
1301 |
> |
* Increment or decrement quiescerCount. Needed only to prevent |
1302 |
> |
* triggering shutdown if a worker is transiently inactive while |
1303 |
> |
* checking quiescence. |
1304 |
> |
* |
1305 |
> |
* @param delta 1 for increment, -1 for decrement |
1306 |
|
*/ |
1307 |
< |
private <T> void doSubmit(ForkJoinTask<T> task) { |
1308 |
< |
if (isShutdown()) |
1309 |
< |
throw new RejectedExecutionException(); |
1310 |
< |
submissionQueue.offer(task); |
1311 |
< |
signalIdleWorkers(true); |
1307 |
> |
final void addQuiescerCount(int delta) { |
1308 |
> |
int c; |
1309 |
> |
do {} while(!UNSAFE.compareAndSwapInt(this, quiescerCountOffset, |
1310 |
> |
c = quiescerCount, c + delta)); |
1311 |
> |
} |
1312 |
> |
|
1313 |
> |
/** |
1314 |
> |
* Directly increment or decrement active count without |
1315 |
> |
* queuing. This method is used to transiently assert inactivation |
1316 |
> |
* while checking quiescence. |
1317 |
> |
* |
1318 |
> |
* @param delta 1 for increment, -1 for decrement |
1319 |
> |
*/ |
1320 |
> |
final void addActiveCount(int delta) { |
1321 |
> |
long d = delta < 0 ? -AC_UNIT : AC_UNIT; |
1322 |
> |
long c; |
1323 |
> |
do {} while (!UNSAFE.compareAndSwapLong(this, ctlOffset, c = ctl, |
1324 |
> |
((c + d) & AC_MASK) | |
1325 |
> |
(c & ~AC_MASK))); |
1326 |
|
} |
1327 |
|
|
1328 |
|
/** |
1329 |
< |
* Performs the given task; returning its result upon completion |
1329 |
> |
* Returns the approximate (non-atomic) number of idle threads per |
1330 |
> |
* active thread. |
1331 |
> |
*/ |
1332 |
> |
final int idlePerActive() { |
1333 |
> |
// Approximate at powers of two for small values, saturate past 4 |
1334 |
> |
int p = parallelism; |
1335 |
> |
int a = p + (int)(ctl >> AC_SHIFT); |
1336 |
> |
return (a > (p >>>= 1) ? 0 : |
1337 |
> |
a > (p >>>= 1) ? 1 : |
1338 |
> |
a > (p >>>= 1) ? 2 : |
1339 |
> |
a > (p >>>= 1) ? 4 : |
1340 |
> |
8); |
1341 |
> |
} |
1342 |
> |
|
1343 |
> |
// Exported methods |
1344 |
> |
|
1345 |
> |
// Constructors |
1346 |
> |
|
1347 |
> |
/** |
1348 |
> |
* Creates a {@code ForkJoinPool} with parallelism equal to {@link |
1349 |
> |
* java.lang.Runtime#availableProcessors}, using the {@linkplain |
1350 |
> |
* #defaultForkJoinWorkerThreadFactory default thread factory}, |
1351 |
> |
* no UncaughtExceptionHandler, and non-async LIFO processing mode. |
1352 |
> |
* |
1353 |
> |
* @throws SecurityException if a security manager exists and |
1354 |
> |
* the caller is not permitted to modify threads |
1355 |
> |
* because it does not hold {@link |
1356 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1357 |
> |
*/ |
1358 |
> |
public ForkJoinPool() { |
1359 |
> |
this(Runtime.getRuntime().availableProcessors(), |
1360 |
> |
defaultForkJoinWorkerThreadFactory, null, false); |
1361 |
> |
} |
1362 |
> |
|
1363 |
> |
/** |
1364 |
> |
* Creates a {@code ForkJoinPool} with the indicated parallelism |
1365 |
> |
* level, the {@linkplain |
1366 |
> |
* #defaultForkJoinWorkerThreadFactory default thread factory}, |
1367 |
> |
* no UncaughtExceptionHandler, and non-async LIFO processing mode. |
1368 |
> |
* |
1369 |
> |
* @param parallelism the parallelism level |
1370 |
> |
* @throws IllegalArgumentException if parallelism less than or |
1371 |
> |
* equal to zero, or greater than implementation limit |
1372 |
> |
* @throws SecurityException if a security manager exists and |
1373 |
> |
* the caller is not permitted to modify threads |
1374 |
> |
* because it does not hold {@link |
1375 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1376 |
> |
*/ |
1377 |
> |
public ForkJoinPool(int parallelism) { |
1378 |
> |
this(parallelism, defaultForkJoinWorkerThreadFactory, null, false); |
1379 |
> |
} |
1380 |
> |
|
1381 |
> |
/** |
1382 |
> |
* Creates a {@code ForkJoinPool} with the given parameters. |
1383 |
> |
* |
1384 |
> |
* @param parallelism the parallelism level. For default value, |
1385 |
> |
* use {@link java.lang.Runtime#availableProcessors}. |
1386 |
> |
* @param factory the factory for creating new threads. For default value, |
1387 |
> |
* use {@link #defaultForkJoinWorkerThreadFactory}. |
1388 |
> |
* @param handler the handler for internal worker threads that |
1389 |
> |
* terminate due to unrecoverable errors encountered while executing |
1390 |
> |
* tasks. For default value, use {@code null}. |
1391 |
> |
* @param asyncMode if true, |
1392 |
> |
* establishes local first-in-first-out scheduling mode for forked |
1393 |
> |
* tasks that are never joined. This mode may be more appropriate |
1394 |
> |
* than default locally stack-based mode in applications in which |
1395 |
> |
* worker threads only process event-style asynchronous tasks. |
1396 |
> |
* For default value, use {@code false}. |
1397 |
> |
* @throws IllegalArgumentException if parallelism less than or |
1398 |
> |
* equal to zero, or greater than implementation limit |
1399 |
> |
* @throws NullPointerException if the factory is null |
1400 |
> |
* @throws SecurityException if a security manager exists and |
1401 |
> |
* the caller is not permitted to modify threads |
1402 |
> |
* because it does not hold {@link |
1403 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1404 |
> |
*/ |
1405 |
> |
public ForkJoinPool(int parallelism, |
1406 |
> |
ForkJoinWorkerThreadFactory factory, |
1407 |
> |
Thread.UncaughtExceptionHandler handler, |
1408 |
> |
boolean asyncMode) { |
1409 |
> |
checkPermission(); |
1410 |
> |
if (factory == null) |
1411 |
> |
throw new NullPointerException(); |
1412 |
> |
if (parallelism <= 0 || parallelism > MAX_ID) |
1413 |
> |
throw new IllegalArgumentException(); |
1414 |
> |
this.parallelism = parallelism; |
1415 |
> |
this.factory = factory; |
1416 |
> |
this.ueh = handler; |
1417 |
> |
this.locallyFifo = asyncMode; |
1418 |
> |
long np = (long)(-parallelism); // offset ctl counts |
1419 |
> |
this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK); |
1420 |
> |
this.submissionQueue = new ForkJoinTask<?>[INITIAL_QUEUE_CAPACITY]; |
1421 |
> |
// initialize workers array with room for 2*parallelism if possible |
1422 |
> |
int n = parallelism << 1; |
1423 |
> |
if (n >= MAX_ID) |
1424 |
> |
n = MAX_ID; |
1425 |
> |
else { // See Hackers Delight, sec 3.2, where n < (1 << 16) |
1426 |
> |
n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; |
1427 |
> |
} |
1428 |
> |
workers = new ForkJoinWorkerThread[n + 1]; |
1429 |
> |
this.submissionLock = new ReentrantLock(); |
1430 |
> |
this.termination = submissionLock.newCondition(); |
1431 |
> |
StringBuilder sb = new StringBuilder("ForkJoinPool-"); |
1432 |
> |
sb.append(poolNumberGenerator.incrementAndGet()); |
1433 |
> |
sb.append("-worker-"); |
1434 |
> |
this.workerNamePrefix = sb.toString(); |
1435 |
> |
} |
1436 |
> |
|
1437 |
> |
// Execution methods |
1438 |
> |
|
1439 |
> |
/** |
1440 |
> |
* Performs the given task, returning its result upon completion. |
1441 |
> |
* If the computation encounters an unchecked Exception or Error, |
1442 |
> |
* it is rethrown as the outcome of this invocation. Rethrown |
1443 |
> |
* exceptions behave in the same way as regular exceptions, but, |
1444 |
> |
* when possible, contain stack traces (as displayed for example |
1445 |
> |
* using {@code ex.printStackTrace()}) of both the current thread |
1446 |
> |
* as well as the thread actually encountering the exception; |
1447 |
> |
* minimally only the latter. |
1448 |
> |
* |
1449 |
|
* @param task the task |
1450 |
|
* @return the task's result |
1451 |
< |
* @throws NullPointerException if task is null |
1452 |
< |
* @throws RejectedExecutionException if pool is shut down |
1451 |
> |
* @throws NullPointerException if the task is null |
1452 |
> |
* @throws RejectedExecutionException if the task cannot be |
1453 |
> |
* scheduled for execution |
1454 |
|
*/ |
1455 |
|
public <T> T invoke(ForkJoinTask<T> task) { |
1456 |
< |
doSubmit(task); |
1457 |
< |
return task.join(); |
1456 |
> |
Thread t = Thread.currentThread(); |
1457 |
> |
if (task == null) |
1458 |
> |
throw new NullPointerException(); |
1459 |
> |
if (shutdown) |
1460 |
> |
throw new RejectedExecutionException(); |
1461 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
1462 |
> |
((ForkJoinWorkerThread)t).pool == this) |
1463 |
> |
return task.invoke(); // bypass submit if in same pool |
1464 |
> |
else { |
1465 |
> |
addSubmission(task); |
1466 |
> |
return task.join(); |
1467 |
> |
} |
1468 |
> |
} |
1469 |
> |
|
1470 |
> |
/** |
1471 |
> |
* Unless terminating, forks task if within an ongoing FJ |
1472 |
> |
* computation in the current pool, else submits as external task. |
1473 |
> |
*/ |
1474 |
> |
private <T> void forkOrSubmit(ForkJoinTask<T> task) { |
1475 |
> |
ForkJoinWorkerThread w; |
1476 |
> |
Thread t = Thread.currentThread(); |
1477 |
> |
if (shutdown) |
1478 |
> |
throw new RejectedExecutionException(); |
1479 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
1480 |
> |
(w = (ForkJoinWorkerThread)t).pool == this) |
1481 |
> |
w.pushTask(task); |
1482 |
> |
else |
1483 |
> |
addSubmission(task); |
1484 |
|
} |
1485 |
|
|
1486 |
|
/** |
1487 |
|
* Arranges for (asynchronous) execution of the given task. |
1488 |
+ |
* |
1489 |
|
* @param task the task |
1490 |
< |
* @throws NullPointerException if task is null |
1491 |
< |
* @throws RejectedExecutionException if pool is shut down |
1490 |
> |
* @throws NullPointerException if the task is null |
1491 |
> |
* @throws RejectedExecutionException if the task cannot be |
1492 |
> |
* scheduled for execution |
1493 |
|
*/ |
1494 |
< |
public <T> void execute(ForkJoinTask<T> task) { |
1495 |
< |
doSubmit(task); |
1494 |
> |
public void execute(ForkJoinTask<?> task) { |
1495 |
> |
if (task == null) |
1496 |
> |
throw new NullPointerException(); |
1497 |
> |
forkOrSubmit(task); |
1498 |
|
} |
1499 |
|
|
1500 |
|
// AbstractExecutorService methods |
1501 |
|
|
1502 |
+ |
/** |
1503 |
+ |
* @throws NullPointerException if the task is null |
1504 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1505 |
+ |
* scheduled for execution |
1506 |
+ |
*/ |
1507 |
|
public void execute(Runnable task) { |
1508 |
< |
doSubmit(new AdaptedRunnable<Void>(task, null)); |
1508 |
> |
if (task == null) |
1509 |
> |
throw new NullPointerException(); |
1510 |
> |
ForkJoinTask<?> job; |
1511 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
1512 |
> |
job = (ForkJoinTask<?>) task; |
1513 |
> |
else |
1514 |
> |
job = ForkJoinTask.adapt(task, null); |
1515 |
> |
forkOrSubmit(job); |
1516 |
|
} |
1517 |
|
|
1518 |
+ |
/** |
1519 |
+ |
* Submits a ForkJoinTask for execution. |
1520 |
+ |
* |
1521 |
+ |
* @param task the task to submit |
1522 |
+ |
* @return the task |
1523 |
+ |
* @throws NullPointerException if the task is null |
1524 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1525 |
+ |
* scheduled for execution |
1526 |
+ |
*/ |
1527 |
+ |
public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) { |
1528 |
+ |
if (task == null) |
1529 |
+ |
throw new NullPointerException(); |
1530 |
+ |
forkOrSubmit(task); |
1531 |
+ |
return task; |
1532 |
+ |
} |
1533 |
+ |
|
1534 |
+ |
/** |
1535 |
+ |
* @throws NullPointerException if the task is null |
1536 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1537 |
+ |
* scheduled for execution |
1538 |
+ |
*/ |
1539 |
|
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
1540 |
< |
ForkJoinTask<T> job = new AdaptedCallable<T>(task); |
1541 |
< |
doSubmit(job); |
1540 |
> |
if (task == null) |
1541 |
> |
throw new NullPointerException(); |
1542 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task); |
1543 |
> |
forkOrSubmit(job); |
1544 |
|
return job; |
1545 |
|
} |
1546 |
|
|
1547 |
+ |
/** |
1548 |
+ |
* @throws NullPointerException if the task is null |
1549 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1550 |
+ |
* scheduled for execution |
1551 |
+ |
*/ |
1552 |
|
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
1553 |
< |
ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result); |
1554 |
< |
doSubmit(job); |
1553 |
> |
if (task == null) |
1554 |
> |
throw new NullPointerException(); |
1555 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task, result); |
1556 |
> |
forkOrSubmit(job); |
1557 |
|
return job; |
1558 |
|
} |
1559 |
|
|
1560 |
+ |
/** |
1561 |
+ |
* @throws NullPointerException if the task is null |
1562 |
+ |
* @throws RejectedExecutionException if the task cannot be |
1563 |
+ |
* scheduled for execution |
1564 |
+ |
*/ |
1565 |
|
public ForkJoinTask<?> submit(Runnable task) { |
1566 |
< |
ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null); |
1567 |
< |
doSubmit(job); |
1566 |
> |
if (task == null) |
1567 |
> |
throw new NullPointerException(); |
1568 |
> |
ForkJoinTask<?> job; |
1569 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
1570 |
> |
job = (ForkJoinTask<?>) task; |
1571 |
> |
else |
1572 |
> |
job = ForkJoinTask.adapt(task, null); |
1573 |
> |
forkOrSubmit(job); |
1574 |
|
return job; |
1575 |
|
} |
1576 |
|
|
1577 |
|
/** |
1578 |
< |
* Adaptor for Runnables. This implements RunnableFuture |
1579 |
< |
* to be compliant with AbstractExecutorService constraints |
1578 |
> |
* @throws NullPointerException {@inheritDoc} |
1579 |
> |
* @throws RejectedExecutionException {@inheritDoc} |
1580 |
|
*/ |
564 |
– |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
565 |
– |
implements RunnableFuture<T> { |
566 |
– |
final Runnable runnable; |
567 |
– |
final T resultOnCompletion; |
568 |
– |
T result; |
569 |
– |
AdaptedRunnable(Runnable runnable, T result) { |
570 |
– |
if (runnable == null) throw new NullPointerException(); |
571 |
– |
this.runnable = runnable; |
572 |
– |
this.resultOnCompletion = result; |
573 |
– |
} |
574 |
– |
public T getRawResult() { return result; } |
575 |
– |
public void setRawResult(T v) { result = v; } |
576 |
– |
public boolean exec() { |
577 |
– |
runnable.run(); |
578 |
– |
result = resultOnCompletion; |
579 |
– |
return true; |
580 |
– |
} |
581 |
– |
public void run() { invoke(); } |
582 |
– |
} |
583 |
– |
|
584 |
– |
/** |
585 |
– |
* Adaptor for Callables |
586 |
– |
*/ |
587 |
– |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
588 |
– |
implements RunnableFuture<T> { |
589 |
– |
final Callable<T> callable; |
590 |
– |
T result; |
591 |
– |
AdaptedCallable(Callable<T> callable) { |
592 |
– |
if (callable == null) throw new NullPointerException(); |
593 |
– |
this.callable = callable; |
594 |
– |
} |
595 |
– |
public T getRawResult() { return result; } |
596 |
– |
public void setRawResult(T v) { result = v; } |
597 |
– |
public boolean exec() { |
598 |
– |
try { |
599 |
– |
result = callable.call(); |
600 |
– |
return true; |
601 |
– |
} catch (Error err) { |
602 |
– |
throw err; |
603 |
– |
} catch (RuntimeException rex) { |
604 |
– |
throw rex; |
605 |
– |
} catch (Exception ex) { |
606 |
– |
throw new RuntimeException(ex); |
607 |
– |
} |
608 |
– |
} |
609 |
– |
public void run() { invoke(); } |
610 |
– |
} |
611 |
– |
|
1581 |
|
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { |
1582 |
< |
ArrayList<ForkJoinTask<T>> ts = |
1582 |
> |
ArrayList<ForkJoinTask<T>> forkJoinTasks = |
1583 |
|
new ArrayList<ForkJoinTask<T>>(tasks.size()); |
1584 |
< |
for (Callable<T> c : tasks) |
1585 |
< |
ts.add(new AdaptedCallable<T>(c)); |
1586 |
< |
invoke(new InvokeAll<T>(ts)); |
1587 |
< |
return (List<Future<T>>)(List)ts; |
1584 |
> |
for (Callable<T> task : tasks) |
1585 |
> |
forkJoinTasks.add(ForkJoinTask.adapt(task)); |
1586 |
> |
invoke(new InvokeAll<T>(forkJoinTasks)); |
1587 |
> |
|
1588 |
> |
@SuppressWarnings({"unchecked", "rawtypes"}) |
1589 |
> |
List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks; |
1590 |
> |
return futures; |
1591 |
|
} |
1592 |
|
|
1593 |
|
static final class InvokeAll<T> extends RecursiveAction { |
1594 |
|
final ArrayList<ForkJoinTask<T>> tasks; |
1595 |
|
InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; } |
1596 |
|
public void compute() { |
1597 |
< |
try { invokeAll(tasks); } catch(Exception ignore) {} |
1597 |
> |
try { invokeAll(tasks); } |
1598 |
> |
catch (Exception ignore) {} |
1599 |
|
} |
1600 |
+ |
private static final long serialVersionUID = -7914297376763021607L; |
1601 |
|
} |
1602 |
|
|
629 |
– |
// Configuration and status settings and queries |
630 |
– |
|
1603 |
|
/** |
1604 |
< |
* Returns the factory used for constructing new workers |
1604 |
> |
* Returns the factory used for constructing new workers. |
1605 |
|
* |
1606 |
|
* @return the factory used for constructing new workers |
1607 |
|
*/ |
1612 |
|
/** |
1613 |
|
* Returns the handler for internal worker threads that terminate |
1614 |
|
* due to unrecoverable errors encountered while executing tasks. |
643 |
– |
* @return the handler, or null if none |
644 |
– |
*/ |
645 |
– |
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
646 |
– |
Thread.UncaughtExceptionHandler h; |
647 |
– |
final ReentrantLock lock = this.workerLock; |
648 |
– |
lock.lock(); |
649 |
– |
try { |
650 |
– |
h = ueh; |
651 |
– |
} finally { |
652 |
– |
lock.unlock(); |
653 |
– |
} |
654 |
– |
return h; |
655 |
– |
} |
656 |
– |
|
657 |
– |
/** |
658 |
– |
* Sets the handler for internal worker threads that terminate due |
659 |
– |
* to unrecoverable errors encountered while executing tasks. |
660 |
– |
* Unless set, the current default or ThreadGroup handler is used |
661 |
– |
* as handler. |
1615 |
|
* |
1616 |
< |
* @param h the new handler |
664 |
< |
* @return the old handler, or null if none |
665 |
< |
* @throws SecurityException if a security manager exists and |
666 |
< |
* the caller is not permitted to modify threads |
667 |
< |
* because it does not hold {@link |
668 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
669 |
< |
*/ |
670 |
< |
public Thread.UncaughtExceptionHandler |
671 |
< |
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) { |
672 |
< |
checkPermission(); |
673 |
< |
Thread.UncaughtExceptionHandler old = null; |
674 |
< |
final ReentrantLock lock = this.workerLock; |
675 |
< |
lock.lock(); |
676 |
< |
try { |
677 |
< |
old = ueh; |
678 |
< |
ueh = h; |
679 |
< |
ForkJoinWorkerThread[] ws = workers; |
680 |
< |
for (int i = 0; i < ws.length; ++i) { |
681 |
< |
ForkJoinWorkerThread w = ws[i]; |
682 |
< |
if (w != null) |
683 |
< |
w.setUncaughtExceptionHandler(h); |
684 |
< |
} |
685 |
< |
} finally { |
686 |
< |
lock.unlock(); |
687 |
< |
} |
688 |
< |
return old; |
689 |
< |
} |
690 |
< |
|
691 |
< |
|
692 |
< |
/** |
693 |
< |
* Sets the target paralleism level of this pool. |
694 |
< |
* @param parallelism the target parallelism |
695 |
< |
* @throws IllegalArgumentException if parallelism less than or |
696 |
< |
* equal to zero or greater than maximum size bounds. |
697 |
< |
* @throws SecurityException if a security manager exists and |
698 |
< |
* the caller is not permitted to modify threads |
699 |
< |
* because it does not hold {@link |
700 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
1616 |
> |
* @return the handler, or {@code null} if none |
1617 |
|
*/ |
1618 |
< |
public void setParallelism(int parallelism) { |
1619 |
< |
checkPermission(); |
704 |
< |
if (parallelism <= 0 || parallelism > maxPoolSize) |
705 |
< |
throw new IllegalArgumentException(); |
706 |
< |
final ReentrantLock lock = this.workerLock; |
707 |
< |
lock.lock(); |
708 |
< |
try { |
709 |
< |
if (!isTerminating()) { |
710 |
< |
int p = this.parallelism; |
711 |
< |
this.parallelism = parallelism; |
712 |
< |
if (parallelism > p) |
713 |
< |
createAndStartAddedWorkers(); |
714 |
< |
else |
715 |
< |
trimSpares(); |
716 |
< |
} |
717 |
< |
} finally { |
718 |
< |
lock.unlock(); |
719 |
< |
} |
720 |
< |
signalIdleWorkers(false); |
1618 |
> |
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
1619 |
> |
return ueh; |
1620 |
|
} |
1621 |
|
|
1622 |
|
/** |
1623 |
< |
* Returns the targeted number of worker threads in this pool. |
1623 |
> |
* Returns the targeted parallelism level of this pool. |
1624 |
|
* |
1625 |
< |
* @return the targeted number of worker threads in this pool |
1625 |
> |
* @return the targeted parallelism level of this pool |
1626 |
|
*/ |
1627 |
|
public int getParallelism() { |
1628 |
|
return parallelism; |
1630 |
|
|
1631 |
|
/** |
1632 |
|
* Returns the number of worker threads that have started but not |
1633 |
< |
* yet terminated. This result returned by this method may differ |
1634 |
< |
* from <code>getParallelism</code> when threads are created to |
1633 |
> |
* yet terminated. The result returned by this method may differ |
1634 |
> |
* from {@link #getParallelism} when threads are created to |
1635 |
|
* maintain parallelism when others are cooperatively blocked. |
1636 |
|
* |
1637 |
|
* @return the number of worker threads |
1638 |
|
*/ |
1639 |
|
public int getPoolSize() { |
1640 |
< |
return totalCountOf(workerCounts); |
742 |
< |
} |
743 |
< |
|
744 |
< |
/** |
745 |
< |
* Returns the maximum number of threads allowed to exist in the |
746 |
< |
* pool, even if there are insufficient unblocked running threads. |
747 |
< |
* @return the maximum |
748 |
< |
*/ |
749 |
< |
public int getMaximumPoolSize() { |
750 |
< |
return maxPoolSize; |
751 |
< |
} |
752 |
< |
|
753 |
< |
/** |
754 |
< |
* Sets the maximum number of threads allowed to exist in the |
755 |
< |
* pool, even if there are insufficient unblocked running threads. |
756 |
< |
* Setting this value has no effect on current pool size. It |
757 |
< |
* controls construction of new threads. |
758 |
< |
* @throws IllegalArgumentException if negative or greater then |
759 |
< |
* internal implementation limit. |
760 |
< |
*/ |
761 |
< |
public void setMaximumPoolSize(int newMax) { |
762 |
< |
if (newMax < 0 || newMax > MAX_THREADS) |
763 |
< |
throw new IllegalArgumentException(); |
764 |
< |
maxPoolSize = newMax; |
765 |
< |
} |
766 |
< |
|
767 |
< |
|
768 |
< |
/** |
769 |
< |
* Returns true if this pool dynamically maintains its target |
770 |
< |
* parallelism level. If false, new threads are added only to |
771 |
< |
* avoid possible starvation. |
772 |
< |
* This setting is by default true; |
773 |
< |
* @return true if maintains parallelism |
774 |
< |
*/ |
775 |
< |
public boolean getMaintainsParallelism() { |
776 |
< |
return maintainsParallelism; |
1640 |
> |
return parallelism + (short)(ctl >>> TC_SHIFT); |
1641 |
|
} |
1642 |
|
|
1643 |
|
/** |
1644 |
< |
* Sets whether this pool dynamically maintains its target |
1645 |
< |
* parallelism level. If false, new threads are added only to |
1646 |
< |
* avoid possible starvation. |
1647 |
< |
* @param enable true to maintains parallelism |
1644 |
> |
* Returns {@code true} if this pool uses local first-in-first-out |
1645 |
> |
* scheduling mode for forked tasks that are never joined. |
1646 |
> |
* |
1647 |
> |
* @return {@code true} if this pool uses async mode |
1648 |
|
*/ |
1649 |
< |
public void setMaintainsParallelism(boolean enable) { |
1650 |
< |
maintainsParallelism = enable; |
1649 |
> |
public boolean getAsyncMode() { |
1650 |
> |
return locallyFifo; |
1651 |
|
} |
1652 |
|
|
1653 |
|
/** |
1654 |
|
* Returns an estimate of the number of worker threads that are |
1655 |
|
* not blocked waiting to join tasks or for other managed |
1656 |
< |
* synchronization. |
1656 |
> |
* synchronization. This method may overestimate the |
1657 |
> |
* number of running threads. |
1658 |
|
* |
1659 |
|
* @return the number of worker threads |
1660 |
|
*/ |
1661 |
|
public int getRunningThreadCount() { |
1662 |
< |
return runningCountOf(workerCounts); |
1662 |
> |
int r = parallelism + (int)(ctl >> AC_SHIFT); |
1663 |
> |
return r <= 0? 0 : r; // suppress momentarily negative values |
1664 |
|
} |
1665 |
|
|
1666 |
|
/** |
1667 |
|
* Returns an estimate of the number of threads that are currently |
1668 |
|
* stealing or executing tasks. This method may overestimate the |
1669 |
|
* number of active threads. |
1670 |
< |
* @return the number of active threads. |
1670 |
> |
* |
1671 |
> |
* @return the number of active threads |
1672 |
|
*/ |
1673 |
|
public int getActiveThreadCount() { |
1674 |
< |
return activeCountOf(runControl); |
1675 |
< |
} |
809 |
< |
|
810 |
< |
/** |
811 |
< |
* Returns an estimate of the number of threads that are currently |
812 |
< |
* idle waiting for tasks. This method may underestimate the |
813 |
< |
* number of idle threads. |
814 |
< |
* @return the number of idle threads. |
815 |
< |
*/ |
816 |
< |
final int getIdleThreadCount() { |
817 |
< |
int c = runningCountOf(workerCounts) - activeCountOf(runControl); |
818 |
< |
return (c <= 0)? 0 : c; |
1674 |
> |
int r = parallelism + (int)(ctl >> AC_SHIFT) + blockedCount; |
1675 |
> |
return r <= 0? 0 : r; // suppress momentarily negative values |
1676 |
|
} |
1677 |
|
|
1678 |
|
/** |
1679 |
< |
* Returns true if all worker threads are currently idle. An idle |
1680 |
< |
* worker is one that cannot obtain a task to execute because none |
1681 |
< |
* are available to steal from other threads, and there are no |
1682 |
< |
* pending submissions to the pool. This method is conservative: |
1683 |
< |
* It might not return true immediately upon idleness of all |
1684 |
< |
* threads, but will eventually become true if threads remain |
1685 |
< |
* inactive. |
1686 |
< |
* @return true if all threads are currently idle |
1679 |
> |
* Returns {@code true} if all worker threads are currently idle. |
1680 |
> |
* An idle worker is one that cannot obtain a task to execute |
1681 |
> |
* because none are available to steal from other threads, and |
1682 |
> |
* there are no pending submissions to the pool. This method is |
1683 |
> |
* conservative; it might not return {@code true} immediately upon |
1684 |
> |
* idleness of all threads, but will eventually become true if |
1685 |
> |
* threads remain inactive. |
1686 |
> |
* |
1687 |
> |
* @return {@code true} if all threads are currently idle |
1688 |
|
*/ |
1689 |
|
public boolean isQuiescent() { |
1690 |
< |
return activeCountOf(runControl) == 0; |
1690 |
> |
return parallelism + (int)(ctl >> AC_SHIFT) + blockedCount == 0; |
1691 |
|
} |
1692 |
|
|
1693 |
|
/** |
1695 |
|
* one thread's work queue by another. The reported value |
1696 |
|
* underestimates the actual total number of steals when the pool |
1697 |
|
* is not quiescent. This value may be useful for monitoring and |
1698 |
< |
* tuning fork/join programs: In general, steal counts should be |
1698 |
> |
* tuning fork/join programs: in general, steal counts should be |
1699 |
|
* high enough to keep threads busy, but low enough to avoid |
1700 |
|
* overhead and contention across threads. |
1701 |
< |
* @return the number of steals. |
1701 |
> |
* |
1702 |
> |
* @return the number of steals |
1703 |
|
*/ |
1704 |
|
public long getStealCount() { |
1705 |
< |
return stealCount.get(); |
847 |
< |
} |
848 |
< |
|
849 |
< |
/** |
850 |
< |
* Accumulate steal count from a worker. Call only |
851 |
< |
* when worker known to be idle. |
852 |
< |
*/ |
853 |
< |
private void updateStealCount(ForkJoinWorkerThread w) { |
854 |
< |
int sc = w.getAndClearStealCount(); |
855 |
< |
if (sc != 0) |
856 |
< |
stealCount.addAndGet(sc); |
1705 |
> |
return stealCount; |
1706 |
|
} |
1707 |
|
|
1708 |
|
/** |
1712 |
|
* an approximation, obtained by iterating across all threads in |
1713 |
|
* the pool. This method may be useful for tuning task |
1714 |
|
* granularities. |
1715 |
< |
* @return the number of queued tasks. |
1715 |
> |
* |
1716 |
> |
* @return the number of queued tasks |
1717 |
|
*/ |
1718 |
|
public long getQueuedTaskCount() { |
1719 |
|
long count = 0; |
1720 |
< |
ForkJoinWorkerThread[] ws = workers; |
1721 |
< |
for (int i = 0; i < ws.length; ++i) { |
1722 |
< |
ForkJoinWorkerThread t = ws[i]; |
1723 |
< |
if (t != null) |
1724 |
< |
count += t.getQueueSize(); |
1720 |
> |
ForkJoinWorkerThread[] ws; |
1721 |
> |
if ((short)(ctl >>> TC_SHIFT) > -parallelism && |
1722 |
> |
(ws = workers) != null) { |
1723 |
> |
for (ForkJoinWorkerThread w : ws) |
1724 |
> |
if (w != null) |
1725 |
> |
count -= w.queueBase - w.queueTop; // must read base first |
1726 |
|
} |
1727 |
|
return count; |
1728 |
|
} |
1729 |
|
|
1730 |
|
/** |
1731 |
< |
* Returns an estimate of the number tasks submitted to this pool |
1732 |
< |
* that have not yet begun executing. This method takes time |
1733 |
< |
* proportional to the number of submissions. |
1734 |
< |
* @return the number of queued submissions. |
1731 |
> |
* Returns an estimate of the number of tasks submitted to this |
1732 |
> |
* pool that have not yet begun executing. This meThod may take |
1733 |
> |
* time proportional to the number of submissions. |
1734 |
> |
* |
1735 |
> |
* @return the number of queued submissions |
1736 |
|
*/ |
1737 |
|
public int getQueuedSubmissionCount() { |
1738 |
< |
return submissionQueue.size(); |
1738 |
> |
return -queueBase + queueTop; |
1739 |
|
} |
1740 |
|
|
1741 |
|
/** |
1742 |
< |
* Returns true if there are any tasks submitted to this pool |
1743 |
< |
* that have not yet begun executing. |
1744 |
< |
* @return <code>true</code> if there are any queued submissions. |
1742 |
> |
* Returns {@code true} if there are any tasks submitted to this |
1743 |
> |
* pool that have not yet begun executing. |
1744 |
> |
* |
1745 |
> |
* @return {@code true} if there are any queued submissions |
1746 |
|
*/ |
1747 |
|
public boolean hasQueuedSubmissions() { |
1748 |
< |
return !submissionQueue.isEmpty(); |
1748 |
> |
return queueBase != queueTop; |
1749 |
|
} |
1750 |
|
|
1751 |
|
/** |
1752 |
|
* Removes and returns the next unexecuted submission if one is |
1753 |
|
* available. This method may be useful in extensions to this |
1754 |
|
* class that re-assign work in systems with multiple pools. |
1755 |
< |
* @return the next submission, or null if none |
1755 |
> |
* |
1756 |
> |
* @return the next submission, or {@code null} if none |
1757 |
|
*/ |
1758 |
|
protected ForkJoinTask<?> pollSubmission() { |
1759 |
< |
return submissionQueue.poll(); |
1759 |
> |
ForkJoinTask<?> t; ForkJoinTask<?>[] q; int b, i; |
1760 |
> |
while ((b = queueBase) != queueTop && |
1761 |
> |
(q = submissionQueue) != null && |
1762 |
> |
(i = (q.length - 1) & b) >= 0) { |
1763 |
> |
long u = (i << ASHIFT) + ABASE; |
1764 |
> |
if ((t = q[i]) != null && |
1765 |
> |
queueBase == b && |
1766 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
1767 |
> |
queueBase = b + 1; |
1768 |
> |
return t; |
1769 |
> |
} |
1770 |
> |
} |
1771 |
> |
return null; |
1772 |
> |
} |
1773 |
> |
|
1774 |
> |
/** |
1775 |
> |
* Removes all available unexecuted submitted and forked tasks |
1776 |
> |
* from scheduling queues and adds them to the given collection, |
1777 |
> |
* without altering their execution status. These may include |
1778 |
> |
* artificially generated or wrapped tasks. This method is |
1779 |
> |
* designed to be invoked only when the pool is known to be |
1780 |
> |
* quiescent. Invocations at other times may not remove all |
1781 |
> |
* tasks. A failure encountered while attempting to add elements |
1782 |
> |
* to collection {@code c} may result in elements being in |
1783 |
> |
* neither, either or both collections when the associated |
1784 |
> |
* exception is thrown. The behavior of this operation is |
1785 |
> |
* undefined if the specified collection is modified while the |
1786 |
> |
* operation is in progress. |
1787 |
> |
* |
1788 |
> |
* @param c the collection to transfer elements into |
1789 |
> |
* @return the number of elements transferred |
1790 |
> |
*/ |
1791 |
> |
protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) { |
1792 |
> |
int count = 0; |
1793 |
> |
while (queueBase != queueTop) { |
1794 |
> |
ForkJoinTask<?> t = pollSubmission(); |
1795 |
> |
if (t != null) { |
1796 |
> |
c.add(t); |
1797 |
> |
++count; |
1798 |
> |
} |
1799 |
> |
} |
1800 |
> |
ForkJoinWorkerThread[] ws; |
1801 |
> |
if ((short)(ctl >>> TC_SHIFT) > -parallelism && |
1802 |
> |
(ws = workers) != null) { |
1803 |
> |
for (ForkJoinWorkerThread w : ws) |
1804 |
> |
if (w != null) |
1805 |
> |
count += w.drainTasksTo(c); |
1806 |
> |
} |
1807 |
> |
return count; |
1808 |
|
} |
1809 |
|
|
1810 |
|
/** |
1815 |
|
* @return a string identifying this pool, as well as its state |
1816 |
|
*/ |
1817 |
|
public String toString() { |
916 |
– |
int ps = parallelism; |
917 |
– |
int wc = workerCounts; |
918 |
– |
int rc = runControl; |
1818 |
|
long st = getStealCount(); |
1819 |
|
long qt = getQueuedTaskCount(); |
1820 |
|
long qs = getQueuedSubmissionCount(); |
1821 |
+ |
int pc = parallelism; |
1822 |
+ |
long c = ctl; |
1823 |
+ |
int tc = pc + (short)(c >>> TC_SHIFT); |
1824 |
+ |
int rc = pc + (int)(c >> AC_SHIFT); |
1825 |
+ |
if (rc < 0) // ignore transient negative |
1826 |
+ |
rc = 0; |
1827 |
+ |
int ac = rc + blockedCount; |
1828 |
+ |
String level; |
1829 |
+ |
if ((c & STOP_BIT) != 0) |
1830 |
+ |
level = (tc == 0)? "Terminated" : "Terminating"; |
1831 |
+ |
else |
1832 |
+ |
level = shutdown? "Shutting down" : "Running"; |
1833 |
|
return super.toString() + |
1834 |
< |
"[" + runStateToString(runStateOf(rc)) + |
1835 |
< |
", parallelism = " + ps + |
1836 |
< |
", size = " + totalCountOf(wc) + |
1837 |
< |
", active = " + activeCountOf(rc) + |
1838 |
< |
", running = " + runningCountOf(wc) + |
1834 |
> |
"[" + level + |
1835 |
> |
", parallelism = " + pc + |
1836 |
> |
", size = " + tc + |
1837 |
> |
", active = " + ac + |
1838 |
> |
", running = " + rc + |
1839 |
|
", steals = " + st + |
1840 |
|
", tasks = " + qt + |
1841 |
|
", submissions = " + qs + |
1842 |
|
"]"; |
1843 |
|
} |
1844 |
|
|
934 |
– |
private static String runStateToString(int rs) { |
935 |
– |
switch(rs) { |
936 |
– |
case RUNNING: return "Running"; |
937 |
– |
case SHUTDOWN: return "Shutting down"; |
938 |
– |
case TERMINATING: return "Terminating"; |
939 |
– |
case TERMINATED: return "Terminated"; |
940 |
– |
default: throw new Error("Unknown run state"); |
941 |
– |
} |
942 |
– |
} |
943 |
– |
|
944 |
– |
// lifecycle control |
945 |
– |
|
1845 |
|
/** |
1846 |
|
* Initiates an orderly shutdown in which previously submitted |
1847 |
|
* tasks are executed, but no new tasks will be accepted. |
1848 |
|
* Invocation has no additional effect if already shut down. |
1849 |
|
* Tasks that are in the process of being submitted concurrently |
1850 |
|
* during the course of this method may or may not be rejected. |
1851 |
+ |
* |
1852 |
|
* @throws SecurityException if a security manager exists and |
1853 |
|
* the caller is not permitted to modify threads |
1854 |
|
* because it does not hold {@link |
1855 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
1855 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1856 |
|
*/ |
1857 |
|
public void shutdown() { |
1858 |
|
checkPermission(); |
1859 |
< |
transitionRunStateTo(SHUTDOWN); |
1860 |
< |
if (canTerminateOnShutdown(runControl)) |
961 |
< |
terminateOnShutdown(); |
1859 |
> |
shutdown = true; |
1860 |
> |
tryTerminate(false); |
1861 |
|
} |
1862 |
|
|
1863 |
|
/** |
1864 |
< |
* Attempts to stop all actively executing tasks, and cancels all |
1865 |
< |
* waiting tasks. Tasks that are in the process of being |
1866 |
< |
* submitted or executed concurrently during the course of this |
1867 |
< |
* method may or may not be rejected. Unlike some other executors, |
1868 |
< |
* this method cancels rather than collects non-executed tasks, |
1869 |
< |
* so always returns an empty list. |
1864 |
> |
* Attempts to cancel and/or stop all tasks, and reject all |
1865 |
> |
* subsequently submitted tasks. Tasks that are in the process of |
1866 |
> |
* being submitted or executed concurrently during the course of |
1867 |
> |
* this method may or may not be rejected. This method cancels |
1868 |
> |
* both existing and unexecuted tasks, in order to permit |
1869 |
> |
* termination in the presence of task dependencies. So the method |
1870 |
> |
* always returns an empty list (unlike the case for some other |
1871 |
> |
* Executors). |
1872 |
> |
* |
1873 |
|
* @return an empty list |
1874 |
|
* @throws SecurityException if a security manager exists and |
1875 |
|
* the caller is not permitted to modify threads |
1876 |
|
* because it does not hold {@link |
1877 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
1877 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1878 |
|
*/ |
1879 |
|
public List<Runnable> shutdownNow() { |
1880 |
|
checkPermission(); |
1881 |
< |
terminate(); |
1881 |
> |
shutdown = true; |
1882 |
> |
tryTerminate(true); |
1883 |
|
return Collections.emptyList(); |
1884 |
|
} |
1885 |
|
|
1886 |
|
/** |
1887 |
< |
* Returns <code>true</code> if all tasks have completed following shut down. |
1887 |
> |
* Returns {@code true} if all tasks have completed following shut down. |
1888 |
|
* |
1889 |
< |
* @return <code>true</code> if all tasks have completed following shut down |
1889 |
> |
* @return {@code true} if all tasks have completed following shut down |
1890 |
|
*/ |
1891 |
|
public boolean isTerminated() { |
1892 |
< |
return runStateOf(runControl) == TERMINATED; |
1892 |
> |
long c = ctl; |
1893 |
> |
return ((c & STOP_BIT) != 0L && |
1894 |
> |
(short)(c >>> TC_SHIFT) == -parallelism); |
1895 |
|
} |
1896 |
|
|
1897 |
|
/** |
1898 |
< |
* Returns <code>true</code> if the process of termination has |
1899 |
< |
* commenced but possibly not yet completed. |
1898 |
> |
* Returns {@code true} if the process of termination has |
1899 |
> |
* commenced but not yet completed. This method may be useful for |
1900 |
> |
* debugging. A return of {@code true} reported a sufficient |
1901 |
> |
* period after shutdown may indicate that submitted tasks have |
1902 |
> |
* ignored or suppressed interruption, or are waiting for IO, |
1903 |
> |
* causing this executor not to properly terminate. (See the |
1904 |
> |
* advisory notes for class {@link ForkJoinTask} stating that |
1905 |
> |
* tasks should not normally entail blocking operations. But if |
1906 |
> |
* they do, they must abort them on interrupt.) |
1907 |
|
* |
1908 |
< |
* @return <code>true</code> if terminating |
1908 |
> |
* @return {@code true} if terminating but not yet terminated |
1909 |
|
*/ |
1910 |
|
public boolean isTerminating() { |
1911 |
< |
return runStateOf(runControl) >= TERMINATING; |
1911 |
> |
long c = ctl; |
1912 |
> |
return ((c & STOP_BIT) != 0L && |
1913 |
> |
(short)(c >>> TC_SHIFT) != -parallelism); |
1914 |
> |
} |
1915 |
> |
|
1916 |
> |
/** |
1917 |
> |
* Returns true if terminating or terminated. Used by ForkJoinWorkerThread. |
1918 |
> |
*/ |
1919 |
> |
final boolean isAtLeastTerminating() { |
1920 |
> |
return (ctl & STOP_BIT) != 0L; |
1921 |
|
} |
1922 |
|
|
1923 |
|
/** |
1924 |
< |
* Returns <code>true</code> if this pool has been shut down. |
1924 |
> |
* Returns {@code true} if this pool has been shut down. |
1925 |
|
* |
1926 |
< |
* @return <code>true</code> if this pool has been shut down |
1926 |
> |
* @return {@code true} if this pool has been shut down |
1927 |
|
*/ |
1928 |
|
public boolean isShutdown() { |
1929 |
< |
return runStateOf(runControl) >= SHUTDOWN; |
1929 |
> |
return shutdown; |
1930 |
|
} |
1931 |
|
|
1932 |
|
/** |
1936 |
|
* |
1937 |
|
* @param timeout the maximum time to wait |
1938 |
|
* @param unit the time unit of the timeout argument |
1939 |
< |
* @return <code>true</code> if this executor terminated and |
1940 |
< |
* <code>false</code> if the timeout elapsed before termination |
1939 |
> |
* @return {@code true} if this executor terminated and |
1940 |
> |
* {@code false} if the timeout elapsed before termination |
1941 |
|
* @throws InterruptedException if interrupted while waiting |
1942 |
|
*/ |
1943 |
|
public boolean awaitTermination(long timeout, TimeUnit unit) |
1944 |
|
throws InterruptedException { |
1945 |
|
long nanos = unit.toNanos(timeout); |
1946 |
< |
final ReentrantLock lock = this.workerLock; |
1946 |
> |
final ReentrantLock lock = this.submissionLock; |
1947 |
|
lock.lock(); |
1948 |
|
try { |
1949 |
|
for (;;) { |
1958 |
|
} |
1959 |
|
} |
1960 |
|
|
1040 |
– |
// Shutdown and termination support |
1041 |
– |
|
1042 |
– |
/** |
1043 |
– |
* Callback from terminating worker. Null out the corresponding |
1044 |
– |
* workers slot, and if terminating, try to terminate, else try to |
1045 |
– |
* shrink workers array. |
1046 |
– |
* @param w the worker |
1047 |
– |
*/ |
1048 |
– |
final void workerTerminated(ForkJoinWorkerThread w) { |
1049 |
– |
updateStealCount(w); |
1050 |
– |
updateWorkerCount(-1); |
1051 |
– |
final ReentrantLock lock = this.workerLock; |
1052 |
– |
lock.lock(); |
1053 |
– |
try { |
1054 |
– |
ForkJoinWorkerThread[] ws = workers; |
1055 |
– |
int idx = w.poolIndex; |
1056 |
– |
if (idx >= 0 && idx < ws.length && ws[idx] == w) |
1057 |
– |
ws[idx] = null; |
1058 |
– |
if (totalCountOf(workerCounts) == 0) { |
1059 |
– |
terminate(); // no-op if already terminating |
1060 |
– |
transitionRunStateTo(TERMINATED); |
1061 |
– |
termination.signalAll(); |
1062 |
– |
} |
1063 |
– |
else if (!isTerminating()) { |
1064 |
– |
tryShrinkWorkerArray(); |
1065 |
– |
tryResumeSpare(true); // allow replacement |
1066 |
– |
} |
1067 |
– |
} finally { |
1068 |
– |
lock.unlock(); |
1069 |
– |
} |
1070 |
– |
signalIdleWorkers(false); |
1071 |
– |
} |
1072 |
– |
|
1073 |
– |
/** |
1074 |
– |
* Initiate termination. |
1075 |
– |
*/ |
1076 |
– |
private void terminate() { |
1077 |
– |
if (transitionRunStateTo(TERMINATING)) { |
1078 |
– |
stopAllWorkers(); |
1079 |
– |
resumeAllSpares(); |
1080 |
– |
signalIdleWorkers(true); |
1081 |
– |
cancelQueuedSubmissions(); |
1082 |
– |
cancelQueuedWorkerTasks(); |
1083 |
– |
interruptUnterminatedWorkers(); |
1084 |
– |
signalIdleWorkers(true); // resignal after interrupt |
1085 |
– |
} |
1086 |
– |
} |
1087 |
– |
|
1088 |
– |
/** |
1089 |
– |
* Possibly terminate when on shutdown state |
1090 |
– |
*/ |
1091 |
– |
private void terminateOnShutdown() { |
1092 |
– |
if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl)) |
1093 |
– |
terminate(); |
1094 |
– |
} |
1095 |
– |
|
1096 |
– |
/** |
1097 |
– |
* Clear out and cancel submissions |
1098 |
– |
*/ |
1099 |
– |
private void cancelQueuedSubmissions() { |
1100 |
– |
ForkJoinTask<?> task; |
1101 |
– |
while ((task = pollSubmission()) != null) |
1102 |
– |
task.cancel(false); |
1103 |
– |
} |
1104 |
– |
|
1105 |
– |
/** |
1106 |
– |
* Clean out worker queues. |
1107 |
– |
*/ |
1108 |
– |
private void cancelQueuedWorkerTasks() { |
1109 |
– |
final ReentrantLock lock = this.workerLock; |
1110 |
– |
lock.lock(); |
1111 |
– |
try { |
1112 |
– |
ForkJoinWorkerThread[] ws = workers; |
1113 |
– |
for (int i = 0; i < ws.length; ++i) { |
1114 |
– |
ForkJoinWorkerThread t = ws[i]; |
1115 |
– |
if (t != null) |
1116 |
– |
t.cancelTasks(); |
1117 |
– |
} |
1118 |
– |
} finally { |
1119 |
– |
lock.unlock(); |
1120 |
– |
} |
1121 |
– |
} |
1122 |
– |
|
1123 |
– |
/** |
1124 |
– |
* Set each worker's status to terminating. Requires lock to avoid |
1125 |
– |
* conflicts with add/remove |
1126 |
– |
*/ |
1127 |
– |
private void stopAllWorkers() { |
1128 |
– |
final ReentrantLock lock = this.workerLock; |
1129 |
– |
lock.lock(); |
1130 |
– |
try { |
1131 |
– |
ForkJoinWorkerThread[] ws = workers; |
1132 |
– |
for (int i = 0; i < ws.length; ++i) { |
1133 |
– |
ForkJoinWorkerThread t = ws[i]; |
1134 |
– |
if (t != null) |
1135 |
– |
t.shutdownNow(); |
1136 |
– |
} |
1137 |
– |
} finally { |
1138 |
– |
lock.unlock(); |
1139 |
– |
} |
1140 |
– |
} |
1141 |
– |
|
1142 |
– |
/** |
1143 |
– |
* Interrupt all unterminated workers. This is not required for |
1144 |
– |
* sake of internal control, but may help unstick user code during |
1145 |
– |
* shutdown. |
1146 |
– |
*/ |
1147 |
– |
private void interruptUnterminatedWorkers() { |
1148 |
– |
final ReentrantLock lock = this.workerLock; |
1149 |
– |
lock.lock(); |
1150 |
– |
try { |
1151 |
– |
ForkJoinWorkerThread[] ws = workers; |
1152 |
– |
for (int i = 0; i < ws.length; ++i) { |
1153 |
– |
ForkJoinWorkerThread t = ws[i]; |
1154 |
– |
if (t != null && !t.isTerminated()) { |
1155 |
– |
try { |
1156 |
– |
t.interrupt(); |
1157 |
– |
} catch (SecurityException ignore) { |
1158 |
– |
} |
1159 |
– |
} |
1160 |
– |
} |
1161 |
– |
} finally { |
1162 |
– |
lock.unlock(); |
1163 |
– |
} |
1164 |
– |
} |
1165 |
– |
|
1166 |
– |
|
1167 |
– |
/* |
1168 |
– |
* Nodes for event barrier to manage idle threads. |
1169 |
– |
* |
1170 |
– |
* The event barrier has an event count and a wait queue (actually |
1171 |
– |
* a Treiber stack). Workers are enabled to look for work when |
1172 |
– |
* the eventCount is incremented. If they fail to find some, |
1173 |
– |
* they may wait for next count. Synchronization events occur only |
1174 |
– |
* in enough contexts to maintain overall liveness: |
1175 |
– |
* |
1176 |
– |
* - Submission of a new task to the pool |
1177 |
– |
* - Creation or termination of a worker |
1178 |
– |
* - pool termination |
1179 |
– |
* - A worker pushing a task on an empty queue |
1180 |
– |
* |
1181 |
– |
* The last case (pushing a task) occurs often enough, and is |
1182 |
– |
* heavy enough compared to simple stack pushes to require some |
1183 |
– |
* special handling: Method signalNonEmptyWorkerQueue returns |
1184 |
– |
* without advancing count if the queue appears to be empty. This |
1185 |
– |
* would ordinarily result in races causing some queued waiters |
1186 |
– |
* not to be woken up. To avoid this, a worker in sync |
1187 |
– |
* rescans for tasks after being enqueued if it was the first to |
1188 |
– |
* enqueue, and aborts the wait if finding one, also helping to |
1189 |
– |
* signal others. This works well because the worker has nothing |
1190 |
– |
* better to do anyway, and so might as well help alleviate the |
1191 |
– |
* overhead and contention on the threads actually doing work. |
1192 |
– |
* |
1193 |
– |
* Queue nodes are basic Treiber stack nodes, also used for spare |
1194 |
– |
* stack. |
1195 |
– |
*/ |
1196 |
– |
static final class WaitQueueNode { |
1197 |
– |
WaitQueueNode next; // only written before enqueued |
1198 |
– |
volatile ForkJoinWorkerThread thread; // nulled to cancel wait |
1199 |
– |
final long count; // unused for spare stack |
1200 |
– |
WaitQueueNode(ForkJoinWorkerThread w, long c) { |
1201 |
– |
count = c; |
1202 |
– |
thread = w; |
1203 |
– |
} |
1204 |
– |
final boolean signal() { |
1205 |
– |
ForkJoinWorkerThread t = thread; |
1206 |
– |
thread = null; |
1207 |
– |
if (t != null) { |
1208 |
– |
LockSupport.unpark(t); |
1209 |
– |
return true; |
1210 |
– |
} |
1211 |
– |
return false; |
1212 |
– |
} |
1213 |
– |
} |
1214 |
– |
|
1215 |
– |
/** |
1216 |
– |
* Release at least one thread waiting for event count to advance, |
1217 |
– |
* if one exists. If initial attempt fails, release all threads. |
1218 |
– |
* @param all if false, at first try to only release one thread |
1219 |
– |
* @return current event |
1220 |
– |
*/ |
1221 |
– |
private long releaseIdleWorkers(boolean all) { |
1222 |
– |
long c; |
1223 |
– |
for (;;) { |
1224 |
– |
WaitQueueNode q = barrierStack; |
1225 |
– |
c = eventCount; |
1226 |
– |
long qc; |
1227 |
– |
if (q == null || (qc = q.count) >= c) |
1228 |
– |
break; |
1229 |
– |
if (!all) { |
1230 |
– |
if (casBarrierStack(q, q.next) && q.signal()) |
1231 |
– |
break; |
1232 |
– |
all = true; |
1233 |
– |
} |
1234 |
– |
else if (casBarrierStack(q, null)) { |
1235 |
– |
do { |
1236 |
– |
q.signal(); |
1237 |
– |
} while ((q = q.next) != null); |
1238 |
– |
break; |
1239 |
– |
} |
1240 |
– |
} |
1241 |
– |
return c; |
1242 |
– |
} |
1243 |
– |
|
1244 |
– |
/** |
1245 |
– |
* Returns current barrier event count |
1246 |
– |
* @return current barrier event count |
1247 |
– |
*/ |
1248 |
– |
final long getEventCount() { |
1249 |
– |
long ec = eventCount; |
1250 |
– |
releaseIdleWorkers(true); // release to ensure accurate result |
1251 |
– |
return ec; |
1252 |
– |
} |
1253 |
– |
|
1254 |
– |
/** |
1255 |
– |
* Increment event count and release at least one waiting thread, |
1256 |
– |
* if one exists (released threads will in turn wake up others). |
1257 |
– |
* @param all if true, try to wake up all |
1258 |
– |
*/ |
1259 |
– |
final void signalIdleWorkers(boolean all) { |
1260 |
– |
long c; |
1261 |
– |
do;while (!casEventCount(c = eventCount, c+1)); |
1262 |
– |
releaseIdleWorkers(all); |
1263 |
– |
} |
1264 |
– |
|
1265 |
– |
/** |
1266 |
– |
* Wake up threads waiting to steal a task. Because method |
1267 |
– |
* sync rechecks availability, it is OK to only proceed if |
1268 |
– |
* queue appears to be non-empty. |
1269 |
– |
*/ |
1270 |
– |
final void signalNonEmptyWorkerQueue() { |
1271 |
– |
// If CAS fails another signaller must have succeeded |
1272 |
– |
long c; |
1273 |
– |
if (barrierStack != null && casEventCount(c = eventCount, c+1)) |
1274 |
– |
releaseIdleWorkers(false); |
1275 |
– |
} |
1276 |
– |
|
1277 |
– |
/** |
1278 |
– |
* Waits until event count advances from count, or some thread is |
1279 |
– |
* waiting on a previous count, or there is stealable work |
1280 |
– |
* available. Help wake up others on release. |
1281 |
– |
* @param w the calling worker thread |
1282 |
– |
* @param prev previous value returned by sync (or 0) |
1283 |
– |
* @return current event count |
1284 |
– |
*/ |
1285 |
– |
final long sync(ForkJoinWorkerThread w, long prev) { |
1286 |
– |
updateStealCount(w); |
1287 |
– |
|
1288 |
– |
while (!w.isShutdown() && !isTerminating() && |
1289 |
– |
(parallelism >= runningCountOf(workerCounts) || |
1290 |
– |
!suspendIfSpare(w))) { // prefer suspend to waiting here |
1291 |
– |
WaitQueueNode node = null; |
1292 |
– |
boolean queued = false; |
1293 |
– |
for (;;) { |
1294 |
– |
if (!queued) { |
1295 |
– |
if (eventCount != prev) |
1296 |
– |
break; |
1297 |
– |
WaitQueueNode h = barrierStack; |
1298 |
– |
if (h != null && h.count != prev) |
1299 |
– |
break; // release below and maybe retry |
1300 |
– |
if (node == null) |
1301 |
– |
node = new WaitQueueNode(w, prev); |
1302 |
– |
queued = casBarrierStack(node.next = h, node); |
1303 |
– |
} |
1304 |
– |
else if (Thread.interrupted() || |
1305 |
– |
node.thread == null || |
1306 |
– |
(node.next == null && w.prescan()) || |
1307 |
– |
eventCount != prev) { |
1308 |
– |
node.thread = null; |
1309 |
– |
if (eventCount == prev) // help trigger |
1310 |
– |
casEventCount(prev, prev+1); |
1311 |
– |
break; |
1312 |
– |
} |
1313 |
– |
else |
1314 |
– |
LockSupport.park(this); |
1315 |
– |
} |
1316 |
– |
long ec = eventCount; |
1317 |
– |
if (releaseIdleWorkers(false) != prev) |
1318 |
– |
return ec; |
1319 |
– |
} |
1320 |
– |
return prev; // return old count if aborted |
1321 |
– |
} |
1322 |
– |
|
1323 |
– |
// Parallelism maintenance |
1324 |
– |
|
1325 |
– |
/** |
1326 |
– |
* Decrement running count; if too low, add spare. |
1327 |
– |
* |
1328 |
– |
* Conceptually, all we need to do here is add or resume a |
1329 |
– |
* spare thread when one is about to block (and remove or |
1330 |
– |
* suspend it later when unblocked -- see suspendIfSpare). |
1331 |
– |
* However, implementing this idea requires coping with |
1332 |
– |
* several problems: We have imperfect information about the |
1333 |
– |
* states of threads. Some count updates can and usually do |
1334 |
– |
* lag run state changes, despite arrangements to keep them |
1335 |
– |
* accurate (for example, when possible, updating counts |
1336 |
– |
* before signalling or resuming), especially when running on |
1337 |
– |
* dynamic JVMs that don't optimize the infrequent paths that |
1338 |
– |
* update counts. Generating too many threads can make these |
1339 |
– |
* problems become worse, because excess threads are more |
1340 |
– |
* likely to be context-switched with others, slowing them all |
1341 |
– |
* down, especially if there is no work available, so all are |
1342 |
– |
* busy scanning or idling. Also, excess spare threads can |
1343 |
– |
* only be suspended or removed when they are idle, not |
1344 |
– |
* immediately when they aren't needed. So adding threads will |
1345 |
– |
* raise parallelism level for longer than necessary. Also, |
1346 |
– |
* FJ applications often enounter highly transient peaks when |
1347 |
– |
* many threads are blocked joining, but for less time than it |
1348 |
– |
* takes to create or resume spares. |
1349 |
– |
* |
1350 |
– |
* @param joinMe if non-null, return early if done |
1351 |
– |
* @param maintainParallelism if true, try to stay within |
1352 |
– |
* target counts, else create only to avoid starvation |
1353 |
– |
* @return true if joinMe known to be done |
1354 |
– |
*/ |
1355 |
– |
final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) { |
1356 |
– |
maintainParallelism &= maintainsParallelism; // overrride |
1357 |
– |
boolean dec = false; // true when running count decremented |
1358 |
– |
while (spareStack == null || !tryResumeSpare(dec)) { |
1359 |
– |
int counts = workerCounts; |
1360 |
– |
if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat |
1361 |
– |
if (!needSpare(counts, maintainParallelism)) |
1362 |
– |
break; |
1363 |
– |
if (joinMe.status < 0) |
1364 |
– |
return true; |
1365 |
– |
if (tryAddSpare(counts)) |
1366 |
– |
break; |
1367 |
– |
} |
1368 |
– |
} |
1369 |
– |
return false; |
1370 |
– |
} |
1371 |
– |
|
1372 |
– |
/** |
1373 |
– |
* Same idea as preJoin |
1374 |
– |
*/ |
1375 |
– |
final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){ |
1376 |
– |
maintainParallelism &= maintainsParallelism; |
1377 |
– |
boolean dec = false; |
1378 |
– |
while (spareStack == null || !tryResumeSpare(dec)) { |
1379 |
– |
int counts = workerCounts; |
1380 |
– |
if (dec || (dec = casWorkerCounts(counts, --counts))) { |
1381 |
– |
if (!needSpare(counts, maintainParallelism)) |
1382 |
– |
break; |
1383 |
– |
if (blocker.isReleasable()) |
1384 |
– |
return true; |
1385 |
– |
if (tryAddSpare(counts)) |
1386 |
– |
break; |
1387 |
– |
} |
1388 |
– |
} |
1389 |
– |
return false; |
1390 |
– |
} |
1391 |
– |
|
1392 |
– |
/** |
1393 |
– |
* Returns true if a spare thread appears to be needed. If |
1394 |
– |
* maintaining parallelism, returns true when the deficit in |
1395 |
– |
* running threads is more than the surplus of total threads, and |
1396 |
– |
* there is apparently some work to do. This self-limiting rule |
1397 |
– |
* means that the more threads that have already been added, the |
1398 |
– |
* less parallelism we will tolerate before adding another. |
1399 |
– |
* @param counts current worker counts |
1400 |
– |
* @param maintainParallelism try to maintain parallelism |
1401 |
– |
*/ |
1402 |
– |
private boolean needSpare(int counts, boolean maintainParallelism) { |
1403 |
– |
int ps = parallelism; |
1404 |
– |
int rc = runningCountOf(counts); |
1405 |
– |
int tc = totalCountOf(counts); |
1406 |
– |
int runningDeficit = ps - rc; |
1407 |
– |
int totalSurplus = tc - ps; |
1408 |
– |
return (tc < maxPoolSize && |
1409 |
– |
(rc == 0 || totalSurplus < 0 || |
1410 |
– |
(maintainParallelism && |
1411 |
– |
runningDeficit > totalSurplus && mayHaveQueuedWork()))); |
1412 |
– |
} |
1413 |
– |
|
1414 |
– |
/** |
1415 |
– |
* Returns true if at least one worker queue appears to be |
1416 |
– |
* nonempty. This is expensive but not often called. It is not |
1417 |
– |
* critical that this be accurate, but if not, more or fewer |
1418 |
– |
* running threads than desired might be maintained. |
1419 |
– |
*/ |
1420 |
– |
private boolean mayHaveQueuedWork() { |
1421 |
– |
ForkJoinWorkerThread[] ws = workers; |
1422 |
– |
int len = ws.length; |
1423 |
– |
ForkJoinWorkerThread v; |
1424 |
– |
for (int i = 0; i < len; ++i) { |
1425 |
– |
if ((v = ws[i]) != null && v.getRawQueueSize() > 0) { |
1426 |
– |
releaseIdleWorkers(false); // help wake up stragglers |
1427 |
– |
return true; |
1428 |
– |
} |
1429 |
– |
} |
1430 |
– |
return false; |
1431 |
– |
} |
1432 |
– |
|
1433 |
– |
/** |
1434 |
– |
* Add a spare worker if lock available and no more than the |
1435 |
– |
* expected numbers of threads exist |
1436 |
– |
* @return true if successful |
1437 |
– |
*/ |
1438 |
– |
private boolean tryAddSpare(int expectedCounts) { |
1439 |
– |
final ReentrantLock lock = this.workerLock; |
1440 |
– |
int expectedRunning = runningCountOf(expectedCounts); |
1441 |
– |
int expectedTotal = totalCountOf(expectedCounts); |
1442 |
– |
boolean success = false; |
1443 |
– |
boolean locked = false; |
1444 |
– |
// confirm counts while locking; CAS after obtaining lock |
1445 |
– |
try { |
1446 |
– |
for (;;) { |
1447 |
– |
int s = workerCounts; |
1448 |
– |
int tc = totalCountOf(s); |
1449 |
– |
int rc = runningCountOf(s); |
1450 |
– |
if (rc > expectedRunning || tc > expectedTotal) |
1451 |
– |
break; |
1452 |
– |
if (!locked && !(locked = lock.tryLock())) |
1453 |
– |
break; |
1454 |
– |
if (casWorkerCounts(s, workerCountsFor(tc+1, rc+1))) { |
1455 |
– |
createAndStartSpare(tc); |
1456 |
– |
success = true; |
1457 |
– |
break; |
1458 |
– |
} |
1459 |
– |
} |
1460 |
– |
} finally { |
1461 |
– |
if (locked) |
1462 |
– |
lock.unlock(); |
1463 |
– |
} |
1464 |
– |
return success; |
1465 |
– |
} |
1466 |
– |
|
1467 |
– |
/** |
1468 |
– |
* Add the kth spare worker. On entry, pool coounts are already |
1469 |
– |
* adjusted to reflect addition. |
1470 |
– |
*/ |
1471 |
– |
private void createAndStartSpare(int k) { |
1472 |
– |
ForkJoinWorkerThread w = null; |
1473 |
– |
ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(k + 1); |
1474 |
– |
int len = ws.length; |
1475 |
– |
// Probably, we can place at slot k. If not, find empty slot |
1476 |
– |
if (k < len && ws[k] != null) { |
1477 |
– |
for (k = 0; k < len && ws[k] != null; ++k) |
1478 |
– |
; |
1479 |
– |
} |
1480 |
– |
if (k < len && !isTerminating() && (w = createWorker(k)) != null) { |
1481 |
– |
ws[k] = w; |
1482 |
– |
w.start(); |
1483 |
– |
} |
1484 |
– |
else |
1485 |
– |
updateWorkerCount(-1); // adjust on failure |
1486 |
– |
signalIdleWorkers(false); |
1487 |
– |
} |
1488 |
– |
|
1489 |
– |
/** |
1490 |
– |
* Suspend calling thread w if there are excess threads. Called |
1491 |
– |
* only from sync. Spares are enqueued in a Treiber stack |
1492 |
– |
* using the same WaitQueueNodes as barriers. They are resumed |
1493 |
– |
* mainly in preJoin, but are also woken on pool events that |
1494 |
– |
* require all threads to check run state. |
1495 |
– |
* @param w the caller |
1496 |
– |
*/ |
1497 |
– |
private boolean suspendIfSpare(ForkJoinWorkerThread w) { |
1498 |
– |
WaitQueueNode node = null; |
1499 |
– |
int s; |
1500 |
– |
while (parallelism < runningCountOf(s = workerCounts)) { |
1501 |
– |
if (node == null) |
1502 |
– |
node = new WaitQueueNode(w, 0); |
1503 |
– |
if (casWorkerCounts(s, s-1)) { // representation-dependent |
1504 |
– |
// push onto stack |
1505 |
– |
do;while (!casSpareStack(node.next = spareStack, node)); |
1506 |
– |
|
1507 |
– |
// block until released by resumeSpare |
1508 |
– |
while (node.thread != null) { |
1509 |
– |
if (!Thread.interrupted()) |
1510 |
– |
LockSupport.park(this); |
1511 |
– |
} |
1512 |
– |
w.activate(); // help warm up |
1513 |
– |
return true; |
1514 |
– |
} |
1515 |
– |
} |
1516 |
– |
return false; |
1517 |
– |
} |
1518 |
– |
|
1519 |
– |
/** |
1520 |
– |
* Try to pop and resume a spare thread. |
1521 |
– |
* @param updateCount if true, increment running count on success |
1522 |
– |
* @return true if successful |
1523 |
– |
*/ |
1524 |
– |
private boolean tryResumeSpare(boolean updateCount) { |
1525 |
– |
WaitQueueNode q; |
1526 |
– |
while ((q = spareStack) != null) { |
1527 |
– |
if (casSpareStack(q, q.next)) { |
1528 |
– |
if (updateCount) |
1529 |
– |
updateRunningCount(1); |
1530 |
– |
q.signal(); |
1531 |
– |
return true; |
1532 |
– |
} |
1533 |
– |
} |
1534 |
– |
return false; |
1535 |
– |
} |
1536 |
– |
|
1537 |
– |
/** |
1538 |
– |
* Pop and resume all spare threads. Same idea as |
1539 |
– |
* releaseIdleWorkers. |
1540 |
– |
* @return true if any spares released |
1541 |
– |
*/ |
1542 |
– |
private boolean resumeAllSpares() { |
1543 |
– |
WaitQueueNode q; |
1544 |
– |
while ( (q = spareStack) != null) { |
1545 |
– |
if (casSpareStack(q, null)) { |
1546 |
– |
do { |
1547 |
– |
updateRunningCount(1); |
1548 |
– |
q.signal(); |
1549 |
– |
} while ((q = q.next) != null); |
1550 |
– |
return true; |
1551 |
– |
} |
1552 |
– |
} |
1553 |
– |
return false; |
1554 |
– |
} |
1555 |
– |
|
1556 |
– |
/** |
1557 |
– |
* Pop and shutdown excessive spare threads. Call only while |
1558 |
– |
* holding lock. This is not guaranteed to eliminate all excess |
1559 |
– |
* threads, only those suspended as spares, which are the ones |
1560 |
– |
* unlikely to be needed in the future. |
1561 |
– |
*/ |
1562 |
– |
private void trimSpares() { |
1563 |
– |
int surplus = totalCountOf(workerCounts) - parallelism; |
1564 |
– |
WaitQueueNode q; |
1565 |
– |
while (surplus > 0 && (q = spareStack) != null) { |
1566 |
– |
if (casSpareStack(q, null)) { |
1567 |
– |
do { |
1568 |
– |
updateRunningCount(1); |
1569 |
– |
ForkJoinWorkerThread w = q.thread; |
1570 |
– |
if (w != null && surplus > 0 && |
1571 |
– |
runningCountOf(workerCounts) > 0 && w.shutdown()) |
1572 |
– |
--surplus; |
1573 |
– |
q.signal(); |
1574 |
– |
} while ((q = q.next) != null); |
1575 |
– |
} |
1576 |
– |
} |
1577 |
– |
} |
1578 |
– |
|
1579 |
– |
/** |
1580 |
– |
* Returns approximate number of spares, just for diagnostics. |
1581 |
– |
*/ |
1582 |
– |
private int countSpares() { |
1583 |
– |
int sum = 0; |
1584 |
– |
for (WaitQueueNode q = spareStack; q != null; q = q.next) |
1585 |
– |
++sum; |
1586 |
– |
return sum; |
1587 |
– |
} |
1588 |
– |
|
1961 |
|
/** |
1962 |
|
* Interface for extending managed parallelism for tasks running |
1963 |
< |
* in ForkJoinPools. A ManagedBlocker provides two methods. |
1964 |
< |
* Method <code>isReleasable</code> must return true if blocking is not |
1965 |
< |
* necessary. Method <code>block</code> blocks the current thread |
1966 |
< |
* if necessary (perhaps internally invoking isReleasable before |
1967 |
< |
* actually blocking.). |
1963 |
> |
* in {@link ForkJoinPool}s. |
1964 |
> |
* |
1965 |
> |
* <p>A {@code ManagedBlocker} provides two methods. Method |
1966 |
> |
* {@code isReleasable} must return {@code true} if blocking is |
1967 |
> |
* not necessary. Method {@code block} blocks the current thread |
1968 |
> |
* if necessary (perhaps internally invoking {@code isReleasable} |
1969 |
> |
* before actually blocking). The unusual methods in this API |
1970 |
> |
* accommodate synchronizers that may, but don't usually, block |
1971 |
> |
* for long periods. Similarly, they allow more efficient internal |
1972 |
> |
* handling of cases in which additional workers may be, but |
1973 |
> |
* usually are not, needed to ensure sufficient parallelism. |
1974 |
> |
* Toward this end, implementations of method {@code isReleasable} |
1975 |
> |
* must be amenable to repeated invocation. |
1976 |
> |
* |
1977 |
|
* <p>For example, here is a ManagedBlocker based on a |
1978 |
|
* ReentrantLock: |
1979 |
< |
* <pre> |
1980 |
< |
* class ManagedLocker implements ManagedBlocker { |
1981 |
< |
* final ReentrantLock lock; |
1982 |
< |
* boolean hasLock = false; |
1983 |
< |
* ManagedLocker(ReentrantLock lock) { this.lock = lock; } |
1984 |
< |
* public boolean block() { |
1985 |
< |
* if (!hasLock) |
1986 |
< |
* lock.lock(); |
1987 |
< |
* return true; |
1988 |
< |
* } |
1989 |
< |
* public boolean isReleasable() { |
1990 |
< |
* return hasLock || (hasLock = lock.tryLock()); |
1991 |
< |
* } |
1979 |
> |
* <pre> {@code |
1980 |
> |
* class ManagedLocker implements ManagedBlocker { |
1981 |
> |
* final ReentrantLock lock; |
1982 |
> |
* boolean hasLock = false; |
1983 |
> |
* ManagedLocker(ReentrantLock lock) { this.lock = lock; } |
1984 |
> |
* public boolean block() { |
1985 |
> |
* if (!hasLock) |
1986 |
> |
* lock.lock(); |
1987 |
> |
* return true; |
1988 |
> |
* } |
1989 |
> |
* public boolean isReleasable() { |
1990 |
> |
* return hasLock || (hasLock = lock.tryLock()); |
1991 |
> |
* } |
1992 |
> |
* }}</pre> |
1993 |
> |
* |
1994 |
> |
* <p>Here is a class that possibly blocks waiting for an |
1995 |
> |
* item on a given queue: |
1996 |
> |
* <pre> {@code |
1997 |
> |
* class QueueTaker<E> implements ManagedBlocker { |
1998 |
> |
* final BlockingQueue<E> queue; |
1999 |
> |
* volatile E item = null; |
2000 |
> |
* QueueTaker(BlockingQueue<E> q) { this.queue = q; } |
2001 |
> |
* public boolean block() throws InterruptedException { |
2002 |
> |
* if (item == null) |
2003 |
> |
* item = queue.take(); |
2004 |
> |
* return true; |
2005 |
> |
* } |
2006 |
> |
* public boolean isReleasable() { |
2007 |
> |
* return item != null || (item = queue.poll()) != null; |
2008 |
> |
* } |
2009 |
> |
* public E getItem() { // call after pool.managedBlock completes |
2010 |
> |
* return item; |
2011 |
|
* } |
2012 |
< |
* </pre> |
2012 |
> |
* }}</pre> |
2013 |
|
*/ |
2014 |
|
public static interface ManagedBlocker { |
2015 |
|
/** |
2016 |
|
* Possibly blocks the current thread, for example waiting for |
2017 |
|
* a lock or condition. |
2018 |
< |
* @return true if no additional blocking is necessary (i.e., |
2019 |
< |
* if isReleasable would return true). |
2018 |
> |
* |
2019 |
> |
* @return {@code true} if no additional blocking is necessary |
2020 |
> |
* (i.e., if isReleasable would return true) |
2021 |
|
* @throws InterruptedException if interrupted while waiting |
2022 |
< |
* (the method is not required to do so, but is allowe to). |
2022 |
> |
* (the method is not required to do so, but is allowed to) |
2023 |
|
*/ |
2024 |
|
boolean block() throws InterruptedException; |
2025 |
|
|
2026 |
|
/** |
2027 |
< |
* Returns true if blocking is unnecessary. |
2027 |
> |
* Returns {@code true} if blocking is unnecessary. |
2028 |
|
*/ |
2029 |
|
boolean isReleasable(); |
2030 |
|
} |
2031 |
|
|
2032 |
|
/** |
2033 |
|
* Blocks in accord with the given blocker. If the current thread |
2034 |
< |
* is a ForkJoinWorkerThread, this method possibly arranges for a |
2035 |
< |
* spare thread to be activated if necessary to ensure parallelism |
2036 |
< |
* while the current thread is blocked. If |
2037 |
< |
* <code>maintainParallelism</code> is true and the pool supports |
2038 |
< |
* it ({@link #getMaintainsParallelism}), this method attempts to |
2039 |
< |
* maintain the pool's nominal parallelism. Otherwise if activates |
2040 |
< |
* a thread only if necessary to avoid complete starvation. This |
2041 |
< |
* option may be preferable when blockages use timeouts, or are |
2042 |
< |
* almost always brief. |
2043 |
< |
* |
2044 |
< |
* <p> If the caller is not a ForkJoinTask, this method is behaviorally |
2045 |
< |
* equivalent to |
2046 |
< |
* <pre> |
2047 |
< |
* while (!blocker.isReleasable()) |
1647 |
< |
* if (blocker.block()) |
1648 |
< |
* return; |
1649 |
< |
* </pre> |
1650 |
< |
* If the caller is a ForkJoinTask, then the pool may first |
1651 |
< |
* be expanded to ensure parallelism, and later adjusted. |
2034 |
> |
* is a {@link ForkJoinWorkerThread}, this method possibly |
2035 |
> |
* arranges for a spare thread to be activated if necessary to |
2036 |
> |
* ensure sufficient parallelism while the current thread is blocked. |
2037 |
> |
* |
2038 |
> |
* <p>If the caller is not a {@link ForkJoinTask}, this method is |
2039 |
> |
* behaviorally equivalent to |
2040 |
> |
* <pre> {@code |
2041 |
> |
* while (!blocker.isReleasable()) |
2042 |
> |
* if (blocker.block()) |
2043 |
> |
* return; |
2044 |
> |
* }</pre> |
2045 |
> |
* |
2046 |
> |
* If the caller is a {@code ForkJoinTask}, then the pool may |
2047 |
> |
* first be expanded to ensure parallelism, and later adjusted. |
2048 |
|
* |
2049 |
|
* @param blocker the blocker |
2050 |
< |
* @param maintainParallelism if true and supported by this pool, |
1655 |
< |
* attempt to maintain the pool's nominal parallelism; otherwise |
1656 |
< |
* activate a thread only if necessary to avoid complete |
1657 |
< |
* starvation. |
1658 |
< |
* @throws InterruptedException if blocker.block did so. |
2050 |
> |
* @throws InterruptedException if blocker.block did so |
2051 |
|
*/ |
2052 |
< |
public static void managedBlock(ManagedBlocker blocker, |
1661 |
< |
boolean maintainParallelism) |
2052 |
> |
public static void managedBlock(ManagedBlocker blocker) |
2053 |
|
throws InterruptedException { |
2054 |
|
Thread t = Thread.currentThread(); |
2055 |
< |
ForkJoinPool pool = (t instanceof ForkJoinWorkerThread? |
2056 |
< |
((ForkJoinWorkerThread)t).pool : null); |
2057 |
< |
if (!blocker.isReleasable()) { |
2058 |
< |
try { |
2059 |
< |
if (pool == null || |
2060 |
< |
!pool.preBlock(blocker, maintainParallelism)) |
1670 |
< |
awaitBlocker(blocker); |
1671 |
< |
} finally { |
1672 |
< |
if (pool != null) |
1673 |
< |
pool.updateRunningCount(1); |
1674 |
< |
} |
2055 |
> |
if (t instanceof ForkJoinWorkerThread) { |
2056 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
2057 |
> |
w.pool.awaitBlocker(blocker); |
2058 |
> |
} |
2059 |
> |
else { |
2060 |
> |
do {} while (!blocker.isReleasable() && !blocker.block()); |
2061 |
|
} |
2062 |
|
} |
2063 |
|
|
2064 |
< |
private static void awaitBlocker(ManagedBlocker blocker) |
2065 |
< |
throws InterruptedException { |
2066 |
< |
do;while (!blocker.isReleasable() && !blocker.block()); |
1681 |
< |
} |
1682 |
< |
|
1683 |
< |
// AbstractExecutorService overrides |
2064 |
> |
// AbstractExecutorService overrides. These rely on undocumented |
2065 |
> |
// fact that ForkJoinTask.adapt returns ForkJoinTasks that also |
2066 |
> |
// implement RunnableFuture. |
2067 |
|
|
2068 |
|
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { |
2069 |
< |
return new AdaptedRunnable(runnable, value); |
2069 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value); |
2070 |
|
} |
2071 |
|
|
2072 |
|
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { |
2073 |
< |
return new AdaptedCallable(callable); |
2073 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(callable); |
2074 |
|
} |
2075 |
|
|
2076 |
< |
|
2077 |
< |
// Temporary Unsafe mechanics for preliminary release |
2078 |
< |
|
2079 |
< |
static final Unsafe _unsafe; |
2080 |
< |
static final long eventCountOffset; |
2081 |
< |
static final long workerCountsOffset; |
2082 |
< |
static final long runControlOffset; |
2083 |
< |
static final long barrierStackOffset; |
2084 |
< |
static final long spareStackOffset; |
2076 |
> |
// Unsafe mechanics |
2077 |
> |
private static final sun.misc.Unsafe UNSAFE; |
2078 |
> |
private static final long ctlOffset; |
2079 |
> |
private static final long stealCountOffset; |
2080 |
> |
private static final long blockedCountOffset; |
2081 |
> |
private static final long quiescerCountOffset; |
2082 |
> |
private static final long scanGuardOffset; |
2083 |
> |
private static final long nextWorkerNumberOffset; |
2084 |
> |
private static final long ABASE; |
2085 |
> |
private static final int ASHIFT; |
2086 |
|
|
2087 |
|
static { |
2088 |
+ |
poolNumberGenerator = new AtomicInteger(); |
2089 |
+ |
workerSeedGenerator = new Random(); |
2090 |
+ |
modifyThreadPermission = new RuntimePermission("modifyThread"); |
2091 |
+ |
defaultForkJoinWorkerThreadFactory = |
2092 |
+ |
new DefaultForkJoinWorkerThreadFactory(); |
2093 |
+ |
int s; |
2094 |
|
try { |
2095 |
< |
if (ForkJoinPool.class.getClassLoader() != null) { |
2096 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
2097 |
< |
f.setAccessible(true); |
2098 |
< |
_unsafe = (Unsafe)f.get(null); |
2099 |
< |
} |
2100 |
< |
else |
2101 |
< |
_unsafe = Unsafe.getUnsafe(); |
2102 |
< |
eventCountOffset = _unsafe.objectFieldOffset |
2103 |
< |
(ForkJoinPool.class.getDeclaredField("eventCount")); |
2104 |
< |
workerCountsOffset = _unsafe.objectFieldOffset |
2105 |
< |
(ForkJoinPool.class.getDeclaredField("workerCounts")); |
2106 |
< |
runControlOffset = _unsafe.objectFieldOffset |
2107 |
< |
(ForkJoinPool.class.getDeclaredField("runControl")); |
2108 |
< |
barrierStackOffset = _unsafe.objectFieldOffset |
2109 |
< |
(ForkJoinPool.class.getDeclaredField("barrierStack")); |
2110 |
< |
spareStackOffset = _unsafe.objectFieldOffset |
2111 |
< |
(ForkJoinPool.class.getDeclaredField("spareStack")); |
2095 |
> |
UNSAFE = getUnsafe(); |
2096 |
> |
Class k = ForkJoinPool.class; |
2097 |
> |
ctlOffset = UNSAFE.objectFieldOffset |
2098 |
> |
(k.getDeclaredField("ctl")); |
2099 |
> |
stealCountOffset = UNSAFE.objectFieldOffset |
2100 |
> |
(k.getDeclaredField("stealCount")); |
2101 |
> |
blockedCountOffset = UNSAFE.objectFieldOffset |
2102 |
> |
(k.getDeclaredField("blockedCount")); |
2103 |
> |
quiescerCountOffset = UNSAFE.objectFieldOffset |
2104 |
> |
(k.getDeclaredField("quiescerCount")); |
2105 |
> |
scanGuardOffset = UNSAFE.objectFieldOffset |
2106 |
> |
(k.getDeclaredField("scanGuard")); |
2107 |
> |
nextWorkerNumberOffset = UNSAFE.objectFieldOffset |
2108 |
> |
(k.getDeclaredField("nextWorkerNumber")); |
2109 |
> |
Class a = ForkJoinTask[].class; |
2110 |
> |
ABASE = UNSAFE.arrayBaseOffset(a); |
2111 |
> |
s = UNSAFE.arrayIndexScale(a); |
2112 |
|
} catch (Exception e) { |
2113 |
< |
throw new RuntimeException("Could not initialize intrinsics", e); |
2113 |
> |
throw new Error(e); |
2114 |
|
} |
2115 |
+ |
if ((s & (s-1)) != 0) |
2116 |
+ |
throw new Error("data type scale not a power of two"); |
2117 |
+ |
ASHIFT = 31 - Integer.numberOfLeadingZeros(s); |
2118 |
|
} |
2119 |
|
|
2120 |
< |
private boolean casEventCount(long cmp, long val) { |
2121 |
< |
return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val); |
2122 |
< |
} |
2123 |
< |
private boolean casWorkerCounts(int cmp, int val) { |
2124 |
< |
return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val); |
2125 |
< |
} |
2126 |
< |
private boolean casRunControl(int cmp, int val) { |
2127 |
< |
return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val); |
2128 |
< |
} |
2129 |
< |
private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) { |
2130 |
< |
return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val); |
2131 |
< |
} |
2132 |
< |
private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) { |
2133 |
< |
return _unsafe.compareAndSwapObject(this, barrierStackOffset, cmp, val); |
2120 |
> |
/** |
2121 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
2122 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
2123 |
> |
* into a jdk. |
2124 |
> |
* |
2125 |
> |
* @return a sun.misc.Unsafe |
2126 |
> |
*/ |
2127 |
> |
private static sun.misc.Unsafe getUnsafe() { |
2128 |
> |
try { |
2129 |
> |
return sun.misc.Unsafe.getUnsafe(); |
2130 |
> |
} catch (SecurityException se) { |
2131 |
> |
try { |
2132 |
> |
return java.security.AccessController.doPrivileged |
2133 |
> |
(new java.security |
2134 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
2135 |
> |
public sun.misc.Unsafe run() throws Exception { |
2136 |
> |
java.lang.reflect.Field f = sun.misc |
2137 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
2138 |
> |
f.setAccessible(true); |
2139 |
> |
return (sun.misc.Unsafe) f.get(null); |
2140 |
> |
}}); |
2141 |
> |
} catch (java.security.PrivilegedActionException e) { |
2142 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
2143 |
> |
e.getCause()); |
2144 |
> |
} |
2145 |
> |
} |
2146 |
|
} |
2147 |
|
} |