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1.1 |
/* |
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1.2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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1.1 |
*/ |
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package java.util.concurrent; |
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1.9 |
import java.util.concurrent.locks.*; |
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1.2 |
import java.util.*; |
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1.1 |
|
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/** |
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1.17 |
* An {@link ExecutorService} that executes each submitted task using |
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* one of possibly several pooled threads. |
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1.1 |
* |
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1.17 |
* <p>Thread pools address two different problems: they usually |
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* provide improved performance when executing large numbers of |
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* asynchronous tasks, due to reduced per-task invocation overhead, |
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* and they provide a means of bounding and managing the resources, |
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* including threads, consumed when executing a collection of tasks. |
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* |
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1.1 |
* <p>To be useful across a wide range of contexts, this class |
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1.17 |
* provides many adjustable parameters and extensibility hooks. For |
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* example, it can be configured to create a new thread for each task, |
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* or even to execute tasks sequentially in a single thread, in |
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* addition to its most common configuration, which reuses a pool of |
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* threads. However, programmers are urged to use the more convenient |
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1.19 |
* {@link Executors} factory methods <tt>newCachedThreadPool</tt> |
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* (unbounded thread pool, with automatic thread reclamation), |
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1.17 |
* <tt>newFixedThreadPool</tt> (fixed size thread pool), |
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* <tt>newSingleThreadPoolExecutor</tt> (single background thread for |
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* execution of tasks), and <tt>newThreadPerTaskExeceutor</tt> |
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* (execute each task in a new thread), that preconfigure settings for |
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* the most common usage scenarios. |
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* |
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* <p>Each <tt>ThreadPoolExecutor</tt> also maintains some basic |
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* statistics, such as the number of completed tasks, that may be |
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* useful for monitoring and tuning executors. |
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1.1 |
* |
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* <h3>Tuning guide</h3> |
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* <dl> |
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1.2 |
* |
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* <dt>Core and maximum pool size</dt> |
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* |
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1.19 |
* <dd>A <tt>ThreadPoolExecutor</tt> will automatically adjust the |
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* pool size according to the bounds set by corePoolSize and |
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* maximumPoolSize. When a new task is submitted, and fewer than |
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* corePoolSize threads are running, a new thread is created to handle |
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* the request, even if other worker threads are idle. If there are |
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* more than the corePoolSize but less than maximumPoolSize threads |
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* running, a new thread will be created only if the queue is full. |
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* By setting corePoolSize and maximumPoolSize the same, you create a |
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* fixed-size thread pool. By default, even core threads are only |
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* created and started when needed by new tasks, but this can be |
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* overridden dynamically using method <tt>prestartCoreThread</tt>. |
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1.17 |
* </dd> |
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1.2 |
* |
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1.10 |
* <dt>Keep-alive</dt> |
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1.2 |
* |
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* <dd>The keepAliveTime determines what happens to idle threads. If |
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* the pool currently has more than the core number of threads, excess |
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* threads will be terminated if they have been idle for more than the |
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* keepAliveTime.</dd> |
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* |
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1.10 |
* <dt>Queueing</dt> |
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* |
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1.19 |
* <dd>Any {@link BlockingQueue} may be used to transfer and hold |
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* submitted tasks. A good default is a {@link SynchronousQueue} that |
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* hands off tasks to threads without otherwise holding them. This |
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* policy avoids lockups when handling sets of requests that might |
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* have internal dependencies. Using an unbounded queue (for example |
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* a {@link LinkedBlockingQueue}) will cause new tasks to be queued in |
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* cases where all corePoolSize threads are busy, so no more than |
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* corePoolSize threads will be craated. This may be appropriate when |
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* each task is completely independent of others, so tasks cannot |
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* affect each others execution; for example, in a web page server. |
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* When given a choice, a <tt>ThreadPoolExecutor</tt> always prefers |
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* adding a new thread rather than queueing if there are currently |
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* fewer than the current getCorePoolSize threads running, but |
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* otherwise always prefers queuing a request rather than adding a new |
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* thread. |
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1.1 |
* |
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* <p>While queuing can be useful in smoothing out transient bursts of |
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* requests, especially in socket-based services, it is not very well |
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* behaved when commands continue to arrive on average faster than |
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1.17 |
* they can be processed. Queue sizes and maximum pool sizes can |
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* often be traded off for each other. Using large queues and small |
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* pools minimizes CPU usage, OS resources, and context-switching |
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* overhead, but can lead to artifically low throughput. If tasks |
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* frequently block (for example if they are I/O bound), a system may |
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* be able to schedule time for more threads than you otherwise |
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* allow. Use of small queues or queueless handoffs generally requires |
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* larger pool sizes, which keeps CPUs busier but may encounter |
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* unacceptable scheduling overhead, which also decreases throughput. |
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1.1 |
* </dd> |
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1.2 |
* |
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1.1 |
* <dt>Creating new threads</dt> |
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1.2 |
* |
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1.19 |
* <dd>New threads are created using a {@link ThreadFactory}. By |
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* default, threads are created simply with the <tt>new |
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* Thread(Runnable)</tt> constructor, but by supplying a different |
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* ThreadFactory, you can alter the thread's name, thread group, |
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* priority, daemon status, etc. </dd> |
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1.2 |
* |
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1.1 |
* <dt>Before and after intercepts</dt> |
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1.2 |
* |
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1.19 |
* <dd>This class has overridable methods that are called before and |
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* after execution of each task. These can be used to manipulate the |
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* execution environment, for example, reinitializing ThreadLocals, |
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* gathering statistics, or adding log entries. </dd> |
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1.2 |
* |
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1.17 |
* <dt>Rejected tasks</dt> |
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1.2 |
* |
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* <dd>There are a number of factors which can bound the number of |
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* tasks which can execute at once, including the maximum pool size |
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* and the queuing mechanism used. If the executor determines that a |
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* task cannot be executed because it has been refused by the queue |
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* and no threads are available, or because the executor has been shut |
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1.19 |
* down, the {@link RejectedExecutionHandler} |
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* <tt>rejectedExecution</tt> method is invoked. The default |
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* (<tt>AbortPolicy</tt>) handler throws a runtime {@link |
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* RejectedExecutionException} upon rejection. </dd> |
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1.2 |
* |
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1.1 |
* </dl> |
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* |
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* @since 1.5 |
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1.8 |
* @author Doug Lea |
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1.1 |
*/ |
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1.2 |
public class ThreadPoolExecutor implements ExecutorService { |
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/** |
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* Queue used for holding tasks and handing off to worker threads. |
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1.10 |
*/ |
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1.2 |
private final BlockingQueue<Runnable> workQueue; |
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/** |
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* Lock held on updates to poolSize, corePoolSize, maximumPoolSize, and |
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* workers set. |
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1.10 |
*/ |
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1.2 |
private final ReentrantLock mainLock = new ReentrantLock(); |
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/** |
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* Wait condition to support awaitTermination |
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1.10 |
*/ |
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1.2 |
private final Condition termination = mainLock.newCondition(); |
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/** |
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* Set containing all worker threads in pool. |
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1.10 |
*/ |
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1.17 |
private final HashSet<Worker> workers = new HashSet<Worker>(); |
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1.2 |
|
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/** |
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* Timeout in nanosecods for idle threads waiting for work. |
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* Threads use this timeout only when there are more than |
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* corePoolSize present. Otherwise they wait forever for new work. |
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1.10 |
*/ |
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1.2 |
private volatile long keepAliveTime; |
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/** |
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* Core pool size, updated only while holding mainLock, |
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* but volatile to allow concurrent readability even |
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* during updates. |
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1.10 |
*/ |
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1.2 |
private volatile int corePoolSize; |
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/** |
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* Maximum pool size, updated only while holding mainLock |
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* but volatile to allow concurrent readability even |
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* during updates. |
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tim |
1.10 |
*/ |
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1.2 |
private volatile int maximumPoolSize; |
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/** |
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* Current pool size, updated only while holding mainLock |
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* but volatile to allow concurrent readability even |
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* during updates. |
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1.10 |
*/ |
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1.2 |
private volatile int poolSize; |
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/** |
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1.16 |
* Lifecycle state |
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1.10 |
*/ |
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1.16 |
private volatile int runState; |
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1.2 |
|
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1.16 |
// Special values for runState |
184 |
dl |
1.8 |
/** Normal, not-shutdown mode */ |
185 |
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1.16 |
private static final int RUNNING = 0; |
186 |
dl |
1.8 |
/** Controlled shutdown mode */ |
187 |
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1.16 |
private static final int SHUTDOWN = 1; |
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/** Immediate shutdown mode */ |
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private static final int STOP = 2; |
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/** Final state */ |
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private static final int TERMINATED = 3; |
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dl |
1.2 |
|
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/** |
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* Handler called when saturated or shutdown in execute. |
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1.10 |
*/ |
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1.2 |
private volatile RejectedExecutionHandler handler = defaultHandler; |
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/** |
199 |
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* Factory for new threads. |
200 |
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1.10 |
*/ |
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1.2 |
private volatile ThreadFactory threadFactory = defaultThreadFactory; |
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/** |
204 |
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* Tracks largest attained pool size. |
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1.10 |
*/ |
206 |
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1.2 |
private int largestPoolSize; |
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208 |
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/** |
209 |
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* Counter for completed tasks. Updated only on termination of |
210 |
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* worker threads. |
211 |
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1.10 |
*/ |
212 |
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1.2 |
private long completedTaskCount; |
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214 |
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1.8 |
/** |
215 |
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1.16 |
* The default thread factory |
216 |
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1.8 |
*/ |
217 |
tim |
1.10 |
private static final ThreadFactory defaultThreadFactory = |
218 |
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1.2 |
new ThreadFactory() { |
219 |
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public Thread newThread(Runnable r) { |
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return new Thread(r); |
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} |
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}; |
223 |
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224 |
dl |
1.8 |
/** |
225 |
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* The default rejectect execution handler |
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*/ |
227 |
tim |
1.10 |
private static final RejectedExecutionHandler defaultHandler = |
228 |
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1.2 |
new AbortPolicy(); |
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/** |
231 |
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1.17 |
* Invoke the rejected execution handler for the given command. |
232 |
dl |
1.13 |
*/ |
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void reject(Runnable command) { |
234 |
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handler.rejectedExecution(command, this); |
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} |
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/** |
238 |
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1.2 |
* Create and return a new thread running firstTask as its first |
239 |
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* task. Call only while holding mainLock |
240 |
dl |
1.8 |
* @param firstTask the task the new thread should run first (or |
241 |
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* null if none) |
242 |
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* @return the new thread |
243 |
dl |
1.2 |
*/ |
244 |
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private Thread addThread(Runnable firstTask) { |
245 |
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Worker w = new Worker(firstTask); |
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Thread t = threadFactory.newThread(w); |
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w.thread = t; |
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workers.add(w); |
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int nt = ++poolSize; |
250 |
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if (nt > largestPoolSize) |
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largestPoolSize = nt; |
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return t; |
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} |
254 |
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255 |
dl |
1.16 |
|
256 |
dl |
1.15 |
|
257 |
dl |
1.2 |
/** |
258 |
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* Create and start a new thread running firstTask as its first |
259 |
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* task, only if less than corePoolSize threads are running. |
260 |
dl |
1.8 |
* @param firstTask the task the new thread should run first (or |
261 |
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* null if none) |
262 |
dl |
1.2 |
* @return true if successful. |
263 |
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*/ |
264 |
dl |
1.16 |
private boolean addIfUnderCorePoolSize(Runnable firstTask) { |
265 |
dl |
1.2 |
Thread t = null; |
266 |
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mainLock.lock(); |
267 |
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try { |
268 |
tim |
1.10 |
if (poolSize < corePoolSize) |
269 |
dl |
1.8 |
t = addThread(firstTask); |
270 |
tim |
1.14 |
} finally { |
271 |
dl |
1.2 |
mainLock.unlock(); |
272 |
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} |
273 |
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if (t == null) |
274 |
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return false; |
275 |
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t.start(); |
276 |
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return true; |
277 |
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} |
278 |
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279 |
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/** |
280 |
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* Create and start a new thread only if less than maximumPoolSize |
281 |
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* threads are running. The new thread runs as its first task the |
282 |
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* next task in queue, or if there is none, the given task. |
283 |
dl |
1.8 |
* @param firstTask the task the new thread should run first (or |
284 |
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* null if none) |
285 |
dl |
1.2 |
* @return null on failure, else the first task to be run by new thread. |
286 |
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*/ |
287 |
dl |
1.8 |
private Runnable addIfUnderMaximumPoolSize(Runnable firstTask) { |
288 |
dl |
1.2 |
Thread t = null; |
289 |
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Runnable next = null; |
290 |
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mainLock.lock(); |
291 |
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try { |
292 |
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if (poolSize < maximumPoolSize) { |
293 |
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next = workQueue.poll(); |
294 |
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if (next == null) |
295 |
dl |
1.8 |
next = firstTask; |
296 |
dl |
1.2 |
t = addThread(next); |
297 |
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} |
298 |
tim |
1.14 |
} finally { |
299 |
dl |
1.2 |
mainLock.unlock(); |
300 |
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} |
301 |
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if (t == null) |
302 |
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return null; |
303 |
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t.start(); |
304 |
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return next; |
305 |
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} |
306 |
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307 |
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|
308 |
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/** |
309 |
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* Get the next task for a worker thread to run. |
310 |
dl |
1.8 |
* @return the task |
311 |
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* @throws InterruptedException if interrupted while waiting for task |
312 |
dl |
1.2 |
*/ |
313 |
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private Runnable getTask() throws InterruptedException { |
314 |
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for (;;) { |
315 |
dl |
1.16 |
switch(runState) { |
316 |
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case RUNNING: { |
317 |
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if (poolSize <= corePoolSize) // untimed wait if core |
318 |
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return workQueue.take(); |
319 |
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|
320 |
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long timeout = keepAliveTime; |
321 |
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if (timeout <= 0) // die immediately for 0 timeout |
322 |
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return null; |
323 |
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Runnable r = workQueue.poll(timeout, TimeUnit.NANOSECONDS); |
324 |
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if (r != null) |
325 |
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return r; |
326 |
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if (poolSize > corePoolSize) // timed out |
327 |
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return null; |
328 |
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// else, after timeout, pool shrank so shouldn't die, so retry |
329 |
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break; |
330 |
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} |
331 |
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|
332 |
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case SHUTDOWN: { |
333 |
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// Help drain queue |
334 |
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Runnable r = workQueue.poll(); |
335 |
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if (r != null) |
336 |
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return r; |
337 |
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|
338 |
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// Check if can terminate |
339 |
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if (workQueue.isEmpty()) { |
340 |
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interruptIdleWorkers(); |
341 |
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return null; |
342 |
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} |
343 |
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|
344 |
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// There could still be delayed tasks in queue. |
345 |
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// Wait for one, re-checking state upon interruption |
346 |
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try { |
347 |
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return workQueue.take(); |
348 |
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} |
349 |
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catch(InterruptedException ignore) { |
350 |
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} |
351 |
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break; |
352 |
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} |
353 |
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|
354 |
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case STOP: |
355 |
dl |
1.2 |
return null; |
356 |
dl |
1.16 |
default: |
357 |
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assert false; |
358 |
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} |
359 |
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} |
360 |
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} |
361 |
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|
362 |
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/** |
363 |
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* Wake up all threads that might be waiting for tasks. |
364 |
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*/ |
365 |
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void interruptIdleWorkers() { |
366 |
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mainLock.lock(); |
367 |
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try { |
368 |
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for (Iterator<Worker> it = workers.iterator(); it.hasNext(); ) |
369 |
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it.next().interruptIfIdle(); |
370 |
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} finally { |
371 |
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mainLock.unlock(); |
372 |
dl |
1.2 |
} |
373 |
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} |
374 |
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|
375 |
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/** |
376 |
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* Perform bookkeeping for a terminated worker thread. |
377 |
tim |
1.10 |
* @param w the worker |
378 |
dl |
1.2 |
*/ |
379 |
|
|
private void workerDone(Worker w) { |
380 |
|
|
mainLock.lock(); |
381 |
|
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try { |
382 |
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completedTaskCount += w.completedTasks; |
383 |
|
|
workers.remove(w); |
384 |
tim |
1.10 |
if (--poolSize > 0) |
385 |
dl |
1.2 |
return; |
386 |
|
|
|
387 |
dl |
1.16 |
// Else, this is the last thread. Deal with potential shutdown. |
388 |
|
|
|
389 |
|
|
int state = runState; |
390 |
|
|
assert state != TERMINATED; |
391 |
tim |
1.10 |
|
392 |
dl |
1.16 |
if (state != STOP) { |
393 |
|
|
// If there are queued tasks but no threads, create |
394 |
|
|
// replacement. |
395 |
dl |
1.2 |
Runnable r = workQueue.poll(); |
396 |
|
|
if (r != null) { |
397 |
|
|
addThread(r).start(); |
398 |
|
|
return; |
399 |
|
|
} |
400 |
dl |
1.16 |
|
401 |
|
|
// If there are some (presumably delayed) tasks but |
402 |
|
|
// none pollable, create an idle replacement to wait. |
403 |
|
|
if (!workQueue.isEmpty()) { |
404 |
|
|
addThread(null).start(); |
405 |
|
|
return; |
406 |
|
|
} |
407 |
|
|
|
408 |
|
|
// Otherwise, we can exit without replacement |
409 |
|
|
if (state == RUNNING) |
410 |
|
|
return; |
411 |
dl |
1.2 |
} |
412 |
|
|
|
413 |
dl |
1.16 |
// Either state is STOP, or state is SHUTDOWN and there is |
414 |
|
|
// no work to do. So we can terminate. |
415 |
|
|
runState = TERMINATED; |
416 |
dl |
1.2 |
termination.signalAll(); |
417 |
dl |
1.16 |
// fall through to call terminate() outside of lock. |
418 |
tim |
1.14 |
} finally { |
419 |
dl |
1.2 |
mainLock.unlock(); |
420 |
|
|
} |
421 |
|
|
|
422 |
dl |
1.16 |
assert runState == TERMINATED; |
423 |
|
|
terminated(); |
424 |
dl |
1.2 |
} |
425 |
|
|
|
426 |
|
|
/** |
427 |
tim |
1.10 |
* Worker threads |
428 |
dl |
1.2 |
*/ |
429 |
|
|
private class Worker implements Runnable { |
430 |
|
|
|
431 |
|
|
/** |
432 |
|
|
* The runLock is acquired and released surrounding each task |
433 |
|
|
* execution. It mainly protects against interrupts that are |
434 |
|
|
* intended to cancel the worker thread from instead |
435 |
|
|
* interrupting the task being run. |
436 |
|
|
*/ |
437 |
|
|
private final ReentrantLock runLock = new ReentrantLock(); |
438 |
|
|
|
439 |
|
|
/** |
440 |
|
|
* Initial task to run before entering run loop |
441 |
|
|
*/ |
442 |
|
|
private Runnable firstTask; |
443 |
|
|
|
444 |
|
|
/** |
445 |
|
|
* Per thread completed task counter; accumulated |
446 |
|
|
* into completedTaskCount upon termination. |
447 |
|
|
*/ |
448 |
|
|
volatile long completedTasks; |
449 |
|
|
|
450 |
|
|
/** |
451 |
|
|
* Thread this worker is running in. Acts as a final field, |
452 |
|
|
* but cannot be set until thread is created. |
453 |
|
|
*/ |
454 |
|
|
Thread thread; |
455 |
|
|
|
456 |
|
|
Worker(Runnable firstTask) { |
457 |
|
|
this.firstTask = firstTask; |
458 |
|
|
} |
459 |
|
|
|
460 |
|
|
boolean isActive() { |
461 |
|
|
return runLock.isLocked(); |
462 |
|
|
} |
463 |
|
|
|
464 |
|
|
/** |
465 |
|
|
* Interrupt thread if not running a task |
466 |
tim |
1.10 |
*/ |
467 |
dl |
1.2 |
void interruptIfIdle() { |
468 |
|
|
if (runLock.tryLock()) { |
469 |
|
|
try { |
470 |
|
|
thread.interrupt(); |
471 |
tim |
1.14 |
} finally { |
472 |
dl |
1.2 |
runLock.unlock(); |
473 |
|
|
} |
474 |
|
|
} |
475 |
|
|
} |
476 |
|
|
|
477 |
|
|
/** |
478 |
|
|
* Cause thread to die even if running a task. |
479 |
tim |
1.10 |
*/ |
480 |
dl |
1.2 |
void interruptNow() { |
481 |
|
|
thread.interrupt(); |
482 |
|
|
} |
483 |
|
|
|
484 |
|
|
/** |
485 |
|
|
* Run a single task between before/after methods. |
486 |
|
|
*/ |
487 |
|
|
private void runTask(Runnable task) { |
488 |
|
|
runLock.lock(); |
489 |
|
|
try { |
490 |
|
|
// Abort now if immediate cancel. Otherwise, we have |
491 |
|
|
// committed to run this task. |
492 |
dl |
1.16 |
if (runState == STOP) |
493 |
dl |
1.2 |
return; |
494 |
|
|
|
495 |
|
|
Thread.interrupted(); // clear interrupt status on entry |
496 |
|
|
boolean ran = false; |
497 |
|
|
beforeExecute(thread, task); |
498 |
|
|
try { |
499 |
|
|
task.run(); |
500 |
|
|
ran = true; |
501 |
|
|
afterExecute(task, null); |
502 |
|
|
++completedTasks; |
503 |
tim |
1.14 |
} catch(RuntimeException ex) { |
504 |
dl |
1.2 |
if (!ran) |
505 |
|
|
afterExecute(task, ex); |
506 |
dl |
1.17 |
// Else the exception occurred within |
507 |
dl |
1.2 |
// afterExecute itself in which case we don't |
508 |
|
|
// want to call it again. |
509 |
|
|
throw ex; |
510 |
|
|
} |
511 |
tim |
1.14 |
} finally { |
512 |
dl |
1.2 |
runLock.unlock(); |
513 |
|
|
} |
514 |
|
|
} |
515 |
|
|
|
516 |
|
|
/** |
517 |
|
|
* Main run loop |
518 |
|
|
*/ |
519 |
|
|
public void run() { |
520 |
|
|
try { |
521 |
|
|
for (;;) { |
522 |
|
|
Runnable task; |
523 |
|
|
if (firstTask != null) { |
524 |
|
|
task = firstTask; |
525 |
|
|
firstTask = null; |
526 |
tim |
1.14 |
} else { |
527 |
dl |
1.2 |
task = getTask(); |
528 |
|
|
if (task == null) |
529 |
|
|
break; |
530 |
|
|
} |
531 |
|
|
runTask(task); |
532 |
|
|
task = null; // unnecessary but can help GC |
533 |
|
|
} |
534 |
tim |
1.14 |
} catch(InterruptedException ie) { |
535 |
dl |
1.2 |
// fall through |
536 |
tim |
1.14 |
} finally { |
537 |
dl |
1.2 |
workerDone(this); |
538 |
|
|
} |
539 |
|
|
} |
540 |
|
|
} |
541 |
tim |
1.1 |
|
542 |
dl |
1.17 |
// Public methods |
543 |
|
|
|
544 |
tim |
1.1 |
/** |
545 |
dl |
1.17 |
* Creates a new <tt>ThreadPoolExecutor</tt> with the given |
546 |
|
|
* initial parameters. It may be more convenient to use one of |
547 |
dholmes |
1.18 |
* the {@link Executors} factory methods instead of this general |
548 |
dl |
1.17 |
* purpose constructor. |
549 |
tim |
1.1 |
* |
550 |
dl |
1.2 |
* @param corePoolSize the number of threads to keep in the |
551 |
tim |
1.1 |
* pool, even if they are idle. |
552 |
dl |
1.2 |
* @param maximumPoolSize the maximum number of threads to allow in the |
553 |
tim |
1.1 |
* pool. |
554 |
|
|
* @param keepAliveTime when the number of threads is greater than |
555 |
dl |
1.2 |
* the core, this is the maximum time that excess idle threads |
556 |
tim |
1.1 |
* will wait for new tasks before terminating. |
557 |
dl |
1.2 |
* @param unit the time unit for the keepAliveTime |
558 |
tim |
1.1 |
* argument. |
559 |
|
|
* @param workQueue the queue to use for holding tasks before the |
560 |
|
|
* are executed. This queue will hold only the <tt>Runnable</tt> |
561 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
562 |
dl |
1.2 |
* @throws IllegalArgumentException if corePoolSize, or |
563 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
564 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
565 |
tim |
1.1 |
* @throws NullPointerException if <tt>workQueue</tt> is null |
566 |
|
|
*/ |
567 |
dl |
1.2 |
public ThreadPoolExecutor(int corePoolSize, |
568 |
|
|
int maximumPoolSize, |
569 |
tim |
1.1 |
long keepAliveTime, |
570 |
dl |
1.2 |
TimeUnit unit, |
571 |
|
|
BlockingQueue<Runnable> workQueue) { |
572 |
tim |
1.10 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, |
573 |
dl |
1.2 |
defaultThreadFactory, defaultHandler); |
574 |
|
|
} |
575 |
tim |
1.1 |
|
576 |
dl |
1.2 |
/** |
577 |
|
|
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
578 |
|
|
* parameters. |
579 |
|
|
* |
580 |
|
|
* @param corePoolSize the number of threads to keep in the |
581 |
|
|
* pool, even if they are idle. |
582 |
|
|
* @param maximumPoolSize the maximum number of threads to allow in the |
583 |
|
|
* pool. |
584 |
|
|
* @param keepAliveTime when the number of threads is greater than |
585 |
|
|
* the core, this is the maximum time that excess idle threads |
586 |
|
|
* will wait for new tasks before terminating. |
587 |
|
|
* @param unit the time unit for the keepAliveTime |
588 |
|
|
* argument. |
589 |
|
|
* @param workQueue the queue to use for holding tasks before the |
590 |
|
|
* are executed. This queue will hold only the <tt>Runnable</tt> |
591 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
592 |
|
|
* @param threadFactory the factory to use when the executor |
593 |
tim |
1.10 |
* creates a new thread. |
594 |
dl |
1.2 |
* @throws IllegalArgumentException if corePoolSize, or |
595 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
596 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
597 |
tim |
1.10 |
* @throws NullPointerException if <tt>workQueue</tt> |
598 |
dl |
1.2 |
* or <tt>threadFactory</tt> are null. |
599 |
|
|
*/ |
600 |
|
|
public ThreadPoolExecutor(int corePoolSize, |
601 |
|
|
int maximumPoolSize, |
602 |
|
|
long keepAliveTime, |
603 |
|
|
TimeUnit unit, |
604 |
|
|
BlockingQueue<Runnable> workQueue, |
605 |
|
|
ThreadFactory threadFactory) { |
606 |
tim |
1.1 |
|
607 |
tim |
1.10 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, |
608 |
dl |
1.2 |
threadFactory, defaultHandler); |
609 |
|
|
} |
610 |
tim |
1.1 |
|
611 |
dl |
1.2 |
/** |
612 |
|
|
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
613 |
|
|
* parameters. |
614 |
|
|
* |
615 |
|
|
* @param corePoolSize the number of threads to keep in the |
616 |
|
|
* pool, even if they are idle. |
617 |
|
|
* @param maximumPoolSize the maximum number of threads to allow in the |
618 |
|
|
* pool. |
619 |
|
|
* @param keepAliveTime when the number of threads is greater than |
620 |
|
|
* the core, this is the maximum time that excess idle threads |
621 |
|
|
* will wait for new tasks before terminating. |
622 |
|
|
* @param unit the time unit for the keepAliveTime |
623 |
|
|
* argument. |
624 |
|
|
* @param workQueue the queue to use for holding tasks before the |
625 |
|
|
* are executed. This queue will hold only the <tt>Runnable</tt> |
626 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
627 |
|
|
* @param handler the handler to use when execution is blocked |
628 |
|
|
* because the thread bounds and queue capacities are reached. |
629 |
|
|
* @throws IllegalArgumentException if corePoolSize, or |
630 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
631 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
632 |
tim |
1.10 |
* @throws NullPointerException if <tt>workQueue</tt> |
633 |
dl |
1.2 |
* or <tt>handler</tt> are null. |
634 |
|
|
*/ |
635 |
|
|
public ThreadPoolExecutor(int corePoolSize, |
636 |
|
|
int maximumPoolSize, |
637 |
|
|
long keepAliveTime, |
638 |
|
|
TimeUnit unit, |
639 |
|
|
BlockingQueue<Runnable> workQueue, |
640 |
|
|
RejectedExecutionHandler handler) { |
641 |
tim |
1.10 |
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, |
642 |
dl |
1.2 |
defaultThreadFactory, handler); |
643 |
|
|
} |
644 |
tim |
1.1 |
|
645 |
dl |
1.2 |
/** |
646 |
|
|
* Creates a new <tt>ThreadPoolExecutor</tt> with the given initial |
647 |
|
|
* parameters. |
648 |
|
|
* |
649 |
|
|
* @param corePoolSize the number of threads to keep in the |
650 |
|
|
* pool, even if they are idle. |
651 |
|
|
* @param maximumPoolSize the maximum number of threads to allow in the |
652 |
|
|
* pool. |
653 |
|
|
* @param keepAliveTime when the number of threads is greater than |
654 |
|
|
* the core, this is the maximum time that excess idle threads |
655 |
|
|
* will wait for new tasks before terminating. |
656 |
|
|
* @param unit the time unit for the keepAliveTime |
657 |
|
|
* argument. |
658 |
|
|
* @param workQueue the queue to use for holding tasks before the |
659 |
|
|
* are executed. This queue will hold only the <tt>Runnable</tt> |
660 |
|
|
* tasks submitted by the <tt>execute</tt> method. |
661 |
|
|
* @param threadFactory the factory to use when the executor |
662 |
tim |
1.10 |
* creates a new thread. |
663 |
dl |
1.2 |
* @param handler the handler to use when execution is blocked |
664 |
|
|
* because the thread bounds and queue capacities are reached. |
665 |
|
|
* @throws IllegalArgumentException if corePoolSize, or |
666 |
|
|
* keepAliveTime less than zero, or if maximumPoolSize less than or |
667 |
|
|
* equal to zero, or if corePoolSize greater than maximumPoolSize. |
668 |
tim |
1.10 |
* @throws NullPointerException if <tt>workQueue</tt> |
669 |
dl |
1.2 |
* or <tt>threadFactory</tt> or <tt>handler</tt> are null. |
670 |
|
|
*/ |
671 |
|
|
public ThreadPoolExecutor(int corePoolSize, |
672 |
|
|
int maximumPoolSize, |
673 |
|
|
long keepAliveTime, |
674 |
|
|
TimeUnit unit, |
675 |
|
|
BlockingQueue<Runnable> workQueue, |
676 |
|
|
ThreadFactory threadFactory, |
677 |
|
|
RejectedExecutionHandler handler) { |
678 |
tim |
1.10 |
if (corePoolSize < 0 || |
679 |
dl |
1.2 |
maximumPoolSize <= 0 || |
680 |
tim |
1.10 |
maximumPoolSize < corePoolSize || |
681 |
dl |
1.2 |
keepAliveTime < 0) |
682 |
|
|
throw new IllegalArgumentException(); |
683 |
|
|
if (workQueue == null || threadFactory == null || handler == null) |
684 |
|
|
throw new NullPointerException(); |
685 |
|
|
this.corePoolSize = corePoolSize; |
686 |
|
|
this.maximumPoolSize = maximumPoolSize; |
687 |
|
|
this.workQueue = workQueue; |
688 |
|
|
this.keepAliveTime = unit.toNanos(keepAliveTime); |
689 |
|
|
this.threadFactory = threadFactory; |
690 |
|
|
this.handler = handler; |
691 |
tim |
1.1 |
} |
692 |
|
|
|
693 |
dl |
1.2 |
|
694 |
|
|
/** |
695 |
|
|
* Executes the given task sometime in the future. The task |
696 |
|
|
* may execute in a new thread or in an existing pooled thread. |
697 |
|
|
* |
698 |
|
|
* If the task cannot be submitted for execution, either because this |
699 |
|
|
* executor has been shutdown or because its capacity has been reached, |
700 |
tim |
1.10 |
* the task is handled by the current <tt>RejectedExecutionHandler</tt>. |
701 |
dl |
1.2 |
* |
702 |
|
|
* @param command the task to execute |
703 |
|
|
* @throws RejectedExecutionException at discretion of |
704 |
dl |
1.8 |
* <tt>RejectedExecutionHandler</tt>, if task cannot be accepted |
705 |
|
|
* for execution |
706 |
dl |
1.2 |
*/ |
707 |
tim |
1.10 |
public void execute(Runnable command) { |
708 |
dl |
1.2 |
for (;;) { |
709 |
dl |
1.16 |
if (runState != RUNNING) { |
710 |
dl |
1.13 |
reject(command); |
711 |
dl |
1.2 |
return; |
712 |
|
|
} |
713 |
|
|
if (poolSize < corePoolSize && addIfUnderCorePoolSize(command)) |
714 |
|
|
return; |
715 |
|
|
if (workQueue.offer(command)) |
716 |
|
|
return; |
717 |
|
|
Runnable r = addIfUnderMaximumPoolSize(command); |
718 |
|
|
if (r == command) |
719 |
|
|
return; |
720 |
|
|
if (r == null) { |
721 |
dl |
1.13 |
reject(command); |
722 |
dl |
1.2 |
return; |
723 |
|
|
} |
724 |
|
|
// else retry |
725 |
|
|
} |
726 |
tim |
1.1 |
} |
727 |
dl |
1.4 |
|
728 |
dl |
1.2 |
public void shutdown() { |
729 |
|
|
mainLock.lock(); |
730 |
|
|
try { |
731 |
dl |
1.16 |
if (runState == RUNNING) // don't override shutdownNow |
732 |
|
|
runState = SHUTDOWN; |
733 |
dl |
1.2 |
for (Iterator<Worker> it = workers.iterator(); it.hasNext(); ) |
734 |
|
|
it.next().interruptIfIdle(); |
735 |
tim |
1.14 |
} finally { |
736 |
dl |
1.2 |
mainLock.unlock(); |
737 |
|
|
} |
738 |
tim |
1.1 |
} |
739 |
|
|
|
740 |
dl |
1.16 |
|
741 |
dl |
1.2 |
public List shutdownNow() { |
742 |
|
|
mainLock.lock(); |
743 |
|
|
try { |
744 |
dl |
1.16 |
if (runState != TERMINATED) |
745 |
|
|
runState = STOP; |
746 |
dl |
1.2 |
for (Iterator<Worker> it = workers.iterator(); it.hasNext(); ) |
747 |
|
|
it.next().interruptNow(); |
748 |
tim |
1.14 |
} finally { |
749 |
dl |
1.2 |
mainLock.unlock(); |
750 |
|
|
} |
751 |
|
|
return Arrays.asList(workQueue.toArray()); |
752 |
tim |
1.1 |
} |
753 |
|
|
|
754 |
dl |
1.2 |
public boolean isShutdown() { |
755 |
dl |
1.16 |
return runState != RUNNING; |
756 |
|
|
} |
757 |
|
|
|
758 |
|
|
/** |
759 |
|
|
* Return true if this executor is in the process of terminating |
760 |
|
|
* after <tt>shutdown</tt> or <tt>shutdownNow</tt> but has not |
761 |
|
|
* completely terminated. This method may be useful for |
762 |
|
|
* debugging. A return of <tt>true</tt> reported a sufficient |
763 |
|
|
* period after shutdown may indicate that submitted tasks have |
764 |
|
|
* ignored or suppressed interruption, causing this executor not |
765 |
|
|
* to properly terminate. |
766 |
|
|
* @return true if terminating but not yet terminated. |
767 |
|
|
*/ |
768 |
|
|
public boolean isTerminating() { |
769 |
|
|
return runState == STOP; |
770 |
tim |
1.1 |
} |
771 |
|
|
|
772 |
dl |
1.2 |
public boolean isTerminated() { |
773 |
dl |
1.16 |
return runState == TERMINATED; |
774 |
dl |
1.2 |
} |
775 |
tim |
1.1 |
|
776 |
dl |
1.2 |
public boolean awaitTermination(long timeout, TimeUnit unit) |
777 |
|
|
throws InterruptedException { |
778 |
|
|
mainLock.lock(); |
779 |
|
|
try { |
780 |
|
|
return termination.await(timeout, unit); |
781 |
tim |
1.14 |
} finally { |
782 |
dl |
1.2 |
mainLock.unlock(); |
783 |
|
|
} |
784 |
dl |
1.15 |
} |
785 |
|
|
|
786 |
|
|
/** |
787 |
|
|
* Invokes <tt>shutdown</tt> when this executor is no longer |
788 |
|
|
* referenced. |
789 |
|
|
*/ |
790 |
|
|
protected void finalize() { |
791 |
|
|
shutdown(); |
792 |
dl |
1.2 |
} |
793 |
tim |
1.10 |
|
794 |
dl |
1.2 |
/** |
795 |
|
|
* Sets the thread factory used to create new threads. |
796 |
|
|
* |
797 |
|
|
* @param threadFactory the new thread factory |
798 |
tim |
1.11 |
* @see #getThreadFactory |
799 |
dl |
1.2 |
*/ |
800 |
|
|
public void setThreadFactory(ThreadFactory threadFactory) { |
801 |
|
|
this.threadFactory = threadFactory; |
802 |
tim |
1.1 |
} |
803 |
|
|
|
804 |
dl |
1.2 |
/** |
805 |
|
|
* Returns the thread factory used to create new threads. |
806 |
|
|
* |
807 |
|
|
* @return the current thread factory |
808 |
tim |
1.11 |
* @see #setThreadFactory |
809 |
dl |
1.2 |
*/ |
810 |
|
|
public ThreadFactory getThreadFactory() { |
811 |
|
|
return threadFactory; |
812 |
tim |
1.1 |
} |
813 |
|
|
|
814 |
dl |
1.2 |
/** |
815 |
|
|
* Sets a new handler for unexecutable tasks. |
816 |
|
|
* |
817 |
|
|
* @param handler the new handler |
818 |
tim |
1.11 |
* @see #getRejectedExecutionHandler |
819 |
dl |
1.2 |
*/ |
820 |
|
|
public void setRejectedExecutionHandler(RejectedExecutionHandler handler) { |
821 |
|
|
this.handler = handler; |
822 |
|
|
} |
823 |
tim |
1.1 |
|
824 |
dl |
1.2 |
/** |
825 |
|
|
* Returns the current handler for unexecutable tasks. |
826 |
|
|
* |
827 |
|
|
* @return the current handler |
828 |
tim |
1.11 |
* @see #setRejectedExecutionHandler |
829 |
dl |
1.2 |
*/ |
830 |
|
|
public RejectedExecutionHandler getRejectedExecutionHandler() { |
831 |
|
|
return handler; |
832 |
tim |
1.1 |
} |
833 |
|
|
|
834 |
dl |
1.2 |
/** |
835 |
dl |
1.17 |
* Returns the task queue used by this executor. Access to the |
836 |
|
|
* task queue is intended primarily for debugging and monitoring. |
837 |
|
|
* This queue may be in active use. Retrieveing the task queue |
838 |
dl |
1.2 |
* does not prevent queued tasks from executing. |
839 |
|
|
* |
840 |
|
|
* @return the task queue |
841 |
|
|
*/ |
842 |
|
|
public BlockingQueue<Runnable> getQueue() { |
843 |
|
|
return workQueue; |
844 |
tim |
1.1 |
} |
845 |
dl |
1.4 |
|
846 |
|
|
/** |
847 |
|
|
* Removes this task from internal queue if it is present, thus |
848 |
|
|
* causing it not to be run if it has not already started. This |
849 |
|
|
* method may be useful as one part of a cancellation scheme. |
850 |
tim |
1.10 |
* |
851 |
dl |
1.8 |
* @param task the task to remove |
852 |
|
|
* @return true if the task was removed |
853 |
dl |
1.4 |
*/ |
854 |
dl |
1.5 |
public boolean remove(Runnable task) { |
855 |
dl |
1.4 |
return getQueue().remove(task); |
856 |
|
|
} |
857 |
|
|
|
858 |
dl |
1.7 |
|
859 |
|
|
/** |
860 |
dl |
1.16 |
* Tries to remove from the work queue all {@link Cancellable} |
861 |
|
|
* tasks that have been cancelled. This method can be useful as a |
862 |
|
|
* storage reclamation operation, that has no other impact on |
863 |
|
|
* functionality. Cancelled tasks are never executed, but may |
864 |
|
|
* accumulate in work queues until worker threads can actively |
865 |
|
|
* remove them. Invoking this method instead tries to remove them now. |
866 |
|
|
* However, this method may fail to remove all such tasks in |
867 |
|
|
* the presence of interference by other threads. |
868 |
dl |
1.7 |
*/ |
869 |
|
|
|
870 |
|
|
public void purge() { |
871 |
dl |
1.16 |
// Fail if we encounter interference during traversal |
872 |
|
|
try { |
873 |
|
|
Iterator<Runnable> it = getQueue().iterator(); |
874 |
|
|
while (it.hasNext()) { |
875 |
|
|
Runnable r = it.next(); |
876 |
|
|
if (r instanceof Cancellable) { |
877 |
|
|
Cancellable c = (Cancellable)r; |
878 |
|
|
if (c.isCancelled()) |
879 |
|
|
it.remove(); |
880 |
|
|
} |
881 |
dl |
1.7 |
} |
882 |
|
|
} |
883 |
dl |
1.16 |
catch(ConcurrentModificationException ex) { |
884 |
|
|
return; |
885 |
|
|
} |
886 |
dl |
1.7 |
} |
887 |
tim |
1.1 |
|
888 |
|
|
/** |
889 |
dl |
1.2 |
* Sets the core number of threads. This overrides any value set |
890 |
|
|
* in the constructor. If the new value is smaller than the |
891 |
|
|
* current value, excess existing threads will be terminated when |
892 |
|
|
* they next become idle. |
893 |
tim |
1.1 |
* |
894 |
dl |
1.2 |
* @param corePoolSize the new core size |
895 |
tim |
1.10 |
* @throws IllegalArgumentException if <tt>corePoolSize</tt> |
896 |
dl |
1.8 |
* less than zero |
897 |
tim |
1.11 |
* @see #getCorePoolSize |
898 |
tim |
1.1 |
*/ |
899 |
dl |
1.2 |
public void setCorePoolSize(int corePoolSize) { |
900 |
|
|
if (corePoolSize < 0) |
901 |
|
|
throw new IllegalArgumentException(); |
902 |
|
|
mainLock.lock(); |
903 |
|
|
try { |
904 |
|
|
int extra = this.corePoolSize - corePoolSize; |
905 |
|
|
this.corePoolSize = corePoolSize; |
906 |
|
|
if (extra > 0 && poolSize > corePoolSize) { |
907 |
|
|
Iterator<Worker> it = workers.iterator(); |
908 |
tim |
1.10 |
while (it.hasNext() && |
909 |
|
|
extra > 0 && |
910 |
dl |
1.2 |
poolSize > corePoolSize && |
911 |
|
|
workQueue.remainingCapacity() == 0) { |
912 |
|
|
it.next().interruptIfIdle(); |
913 |
|
|
--extra; |
914 |
|
|
} |
915 |
|
|
} |
916 |
tim |
1.10 |
|
917 |
tim |
1.14 |
} finally { |
918 |
dl |
1.2 |
mainLock.unlock(); |
919 |
|
|
} |
920 |
|
|
} |
921 |
tim |
1.1 |
|
922 |
|
|
/** |
923 |
dl |
1.2 |
* Returns the core number of threads. |
924 |
tim |
1.1 |
* |
925 |
dl |
1.2 |
* @return the core number of threads |
926 |
tim |
1.11 |
* @see #setCorePoolSize |
927 |
tim |
1.1 |
*/ |
928 |
tim |
1.10 |
public int getCorePoolSize() { |
929 |
dl |
1.2 |
return corePoolSize; |
930 |
dl |
1.16 |
} |
931 |
|
|
|
932 |
|
|
/** |
933 |
|
|
* Start a core thread, causing it to idly wait for work. This |
934 |
|
|
* overrides the default policy of starting core threads only when |
935 |
|
|
* new tasks are executed. This method will return <tt>false</tt> |
936 |
|
|
* if all core threads have already been started. |
937 |
|
|
* @return true if a thread was started |
938 |
|
|
*/ |
939 |
|
|
public boolean prestartCoreThread() { |
940 |
|
|
return addIfUnderCorePoolSize(null); |
941 |
|
|
} |
942 |
|
|
|
943 |
|
|
/** |
944 |
|
|
* Start all core threads, causing them to idly wait for work. This |
945 |
|
|
* overrides the default policy of starting core threads only when |
946 |
|
|
* new tasks are executed. |
947 |
|
|
* @return the number of threads started. |
948 |
|
|
*/ |
949 |
|
|
public int prestartAllCoreThreads() { |
950 |
|
|
int n = 0; |
951 |
|
|
while (addIfUnderCorePoolSize(null)) |
952 |
|
|
++n; |
953 |
|
|
return n; |
954 |
dl |
1.2 |
} |
955 |
tim |
1.1 |
|
956 |
|
|
/** |
957 |
|
|
* Sets the maximum allowed number of threads. This overrides any |
958 |
dl |
1.2 |
* value set in the constructor. If the new value is smaller than |
959 |
|
|
* the current value, excess existing threads will be |
960 |
|
|
* terminated when they next become idle. |
961 |
tim |
1.1 |
* |
962 |
dl |
1.2 |
* @param maximumPoolSize the new maximum |
963 |
|
|
* @throws IllegalArgumentException if maximumPoolSize less than zero or |
964 |
|
|
* the {@link #getCorePoolSize core pool size} |
965 |
tim |
1.11 |
* @see #getMaximumPoolSize |
966 |
dl |
1.2 |
*/ |
967 |
|
|
public void setMaximumPoolSize(int maximumPoolSize) { |
968 |
|
|
if (maximumPoolSize <= 0 || maximumPoolSize < corePoolSize) |
969 |
|
|
throw new IllegalArgumentException(); |
970 |
|
|
mainLock.lock(); |
971 |
|
|
try { |
972 |
|
|
int extra = this.maximumPoolSize - maximumPoolSize; |
973 |
|
|
this.maximumPoolSize = maximumPoolSize; |
974 |
|
|
if (extra > 0 && poolSize > maximumPoolSize) { |
975 |
|
|
Iterator<Worker> it = workers.iterator(); |
976 |
tim |
1.10 |
while (it.hasNext() && |
977 |
|
|
extra > 0 && |
978 |
dl |
1.2 |
poolSize > maximumPoolSize) { |
979 |
|
|
it.next().interruptIfIdle(); |
980 |
|
|
--extra; |
981 |
|
|
} |
982 |
|
|
} |
983 |
tim |
1.14 |
} finally { |
984 |
dl |
1.2 |
mainLock.unlock(); |
985 |
|
|
} |
986 |
|
|
} |
987 |
tim |
1.1 |
|
988 |
|
|
/** |
989 |
|
|
* Returns the maximum allowed number of threads. |
990 |
|
|
* |
991 |
dl |
1.2 |
* @return the maximum allowed number of threads |
992 |
tim |
1.11 |
* @see #setMaximumPoolSize |
993 |
tim |
1.1 |
*/ |
994 |
tim |
1.10 |
public int getMaximumPoolSize() { |
995 |
dl |
1.2 |
return maximumPoolSize; |
996 |
|
|
} |
997 |
tim |
1.1 |
|
998 |
|
|
/** |
999 |
|
|
* Sets the time limit for which threads may remain idle before |
1000 |
dl |
1.2 |
* being terminated. If there are more than the core number of |
1001 |
tim |
1.1 |
* threads currently in the pool, after waiting this amount of |
1002 |
|
|
* time without processing a task, excess threads will be |
1003 |
|
|
* terminated. This overrides any value set in the constructor. |
1004 |
|
|
* @param time the time to wait. A time value of zero will cause |
1005 |
|
|
* excess threads to terminate immediately after executing tasks. |
1006 |
dl |
1.2 |
* @param unit the time unit of the time argument |
1007 |
dl |
1.17 |
* @throws IllegalArgumentException if time less than zero |
1008 |
tim |
1.11 |
* @see #getKeepAliveTime |
1009 |
tim |
1.1 |
*/ |
1010 |
dl |
1.2 |
public void setKeepAliveTime(long time, TimeUnit unit) { |
1011 |
|
|
if (time < 0) |
1012 |
|
|
throw new IllegalArgumentException(); |
1013 |
|
|
this.keepAliveTime = unit.toNanos(time); |
1014 |
|
|
} |
1015 |
tim |
1.1 |
|
1016 |
|
|
/** |
1017 |
|
|
* Returns the thread keep-alive time, which is the amount of time |
1018 |
dl |
1.2 |
* which threads in excess of the core pool size may remain |
1019 |
tim |
1.10 |
* idle before being terminated. |
1020 |
tim |
1.1 |
* |
1021 |
dl |
1.2 |
* @param unit the desired time unit of the result |
1022 |
tim |
1.1 |
* @return the time limit |
1023 |
tim |
1.11 |
* @see #setKeepAliveTime |
1024 |
tim |
1.1 |
*/ |
1025 |
tim |
1.10 |
public long getKeepAliveTime(TimeUnit unit) { |
1026 |
dl |
1.2 |
return unit.convert(keepAliveTime, TimeUnit.NANOSECONDS); |
1027 |
|
|
} |
1028 |
tim |
1.1 |
|
1029 |
|
|
/* Statistics */ |
1030 |
|
|
|
1031 |
|
|
/** |
1032 |
|
|
* Returns the current number of threads in the pool. |
1033 |
|
|
* |
1034 |
|
|
* @return the number of threads |
1035 |
|
|
*/ |
1036 |
tim |
1.10 |
public int getPoolSize() { |
1037 |
dl |
1.2 |
return poolSize; |
1038 |
|
|
} |
1039 |
tim |
1.1 |
|
1040 |
|
|
/** |
1041 |
dl |
1.2 |
* Returns the approximate number of threads that are actively |
1042 |
tim |
1.1 |
* executing tasks. |
1043 |
|
|
* |
1044 |
|
|
* @return the number of threads |
1045 |
|
|
*/ |
1046 |
tim |
1.10 |
public int getActiveCount() { |
1047 |
dl |
1.2 |
mainLock.lock(); |
1048 |
|
|
try { |
1049 |
|
|
int n = 0; |
1050 |
|
|
for (Iterator<Worker> it = workers.iterator(); it.hasNext(); ) { |
1051 |
|
|
if (it.next().isActive()) |
1052 |
|
|
++n; |
1053 |
|
|
} |
1054 |
|
|
return n; |
1055 |
tim |
1.14 |
} finally { |
1056 |
dl |
1.2 |
mainLock.unlock(); |
1057 |
|
|
} |
1058 |
|
|
} |
1059 |
tim |
1.1 |
|
1060 |
|
|
/** |
1061 |
dl |
1.2 |
* Returns the largest number of threads that have ever |
1062 |
|
|
* simultaneously been in the pool. |
1063 |
tim |
1.1 |
* |
1064 |
|
|
* @return the number of threads |
1065 |
|
|
*/ |
1066 |
tim |
1.10 |
public int getLargestPoolSize() { |
1067 |
dl |
1.2 |
mainLock.lock(); |
1068 |
|
|
try { |
1069 |
|
|
return largestPoolSize; |
1070 |
tim |
1.14 |
} finally { |
1071 |
dl |
1.2 |
mainLock.unlock(); |
1072 |
|
|
} |
1073 |
|
|
} |
1074 |
tim |
1.1 |
|
1075 |
|
|
/** |
1076 |
dl |
1.2 |
* Returns the approximate total number of tasks that have been |
1077 |
|
|
* scheduled for execution. Because the states of tasks and |
1078 |
|
|
* threads may change dynamically during computation, the returned |
1079 |
dl |
1.17 |
* value is only an approximation, but one that does not ever |
1080 |
|
|
* decrease across successive calls. |
1081 |
tim |
1.1 |
* |
1082 |
|
|
* @return the number of tasks |
1083 |
|
|
*/ |
1084 |
tim |
1.10 |
public long getTaskCount() { |
1085 |
dl |
1.2 |
mainLock.lock(); |
1086 |
|
|
try { |
1087 |
|
|
long n = completedTaskCount; |
1088 |
|
|
for (Iterator<Worker> it = workers.iterator(); it.hasNext(); ) { |
1089 |
|
|
Worker w = it.next(); |
1090 |
|
|
n += w.completedTasks; |
1091 |
|
|
if (w.isActive()) |
1092 |
|
|
++n; |
1093 |
|
|
} |
1094 |
|
|
return n + workQueue.size(); |
1095 |
tim |
1.14 |
} finally { |
1096 |
dl |
1.2 |
mainLock.unlock(); |
1097 |
|
|
} |
1098 |
|
|
} |
1099 |
tim |
1.1 |
|
1100 |
|
|
/** |
1101 |
dl |
1.2 |
* Returns the approximate total number of tasks that have |
1102 |
|
|
* completed execution. Because the states of tasks and threads |
1103 |
|
|
* may change dynamically during computation, the returned value |
1104 |
dl |
1.17 |
* is only an approximation, but one that does not ever decrease |
1105 |
|
|
* across successive calls. |
1106 |
tim |
1.1 |
* |
1107 |
|
|
* @return the number of tasks |
1108 |
|
|
*/ |
1109 |
tim |
1.10 |
public long getCompletedTaskCount() { |
1110 |
dl |
1.2 |
mainLock.lock(); |
1111 |
|
|
try { |
1112 |
|
|
long n = completedTaskCount; |
1113 |
tim |
1.10 |
for (Iterator<Worker> it = workers.iterator(); it.hasNext(); ) |
1114 |
dl |
1.2 |
n += it.next().completedTasks; |
1115 |
|
|
return n; |
1116 |
tim |
1.14 |
} finally { |
1117 |
dl |
1.2 |
mainLock.unlock(); |
1118 |
|
|
} |
1119 |
|
|
} |
1120 |
tim |
1.1 |
|
1121 |
|
|
/** |
1122 |
dl |
1.17 |
* Method invoked prior to executing the given Runnable in the |
1123 |
|
|
* given thread. This method may be used to re-initialize |
1124 |
|
|
* ThreadLocals, or to perform logging. Note: To properly nest |
1125 |
|
|
* multiple overridings, subclasses should generally invoke |
1126 |
dl |
1.5 |
* <tt>super.beforeExecute</tt> at the end of this method. |
1127 |
tim |
1.1 |
* |
1128 |
dl |
1.2 |
* @param t the thread that will run task r. |
1129 |
|
|
* @param r the task that will be executed. |
1130 |
tim |
1.1 |
*/ |
1131 |
dl |
1.2 |
protected void beforeExecute(Thread t, Runnable r) { } |
1132 |
tim |
1.1 |
|
1133 |
|
|
/** |
1134 |
dl |
1.2 |
* Method invoked upon completion of execution of the given |
1135 |
|
|
* Runnable. If non-null, the Throwable is the uncaught exception |
1136 |
dl |
1.5 |
* that caused execution to terminate abruptly. Note: To properly |
1137 |
|
|
* nest multiple overridings, subclasses should generally invoke |
1138 |
|
|
* <tt>super.afterExecute</tt> at the beginning of this method. |
1139 |
tim |
1.1 |
* |
1140 |
dl |
1.2 |
* @param r the runnable that has completed. |
1141 |
|
|
* @param t the exception that cause termination, or null if |
1142 |
|
|
* execution completed normally. |
1143 |
tim |
1.1 |
*/ |
1144 |
dl |
1.2 |
protected void afterExecute(Runnable r, Throwable t) { } |
1145 |
tim |
1.1 |
|
1146 |
dl |
1.2 |
/** |
1147 |
|
|
* Method invoked when the Executor has terminated. Default |
1148 |
dl |
1.17 |
* implementation does nothing. Note: To properly nest multiple |
1149 |
|
|
* overridings, subclasses should generally invoke |
1150 |
|
|
* <tt>super.terminated</tt> within this method. |
1151 |
dl |
1.2 |
*/ |
1152 |
|
|
protected void terminated() { } |
1153 |
tim |
1.1 |
|
1154 |
|
|
/** |
1155 |
dl |
1.17 |
* A handler for unexecutable tasks that runs these tasks directly |
1156 |
|
|
* in the calling thread of the <tt>execute</tt> method. This is |
1157 |
|
|
* the default <tt>RejectedExecutionHandler</tt>. |
1158 |
tim |
1.1 |
*/ |
1159 |
dl |
1.2 |
public static class CallerRunsPolicy implements RejectedExecutionHandler { |
1160 |
tim |
1.1 |
|
1161 |
|
|
/** |
1162 |
|
|
* Constructs a <tt>CallerRunsPolicy</tt>. |
1163 |
|
|
*/ |
1164 |
|
|
public CallerRunsPolicy() { } |
1165 |
|
|
|
1166 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1167 |
|
|
if (!e.isShutdown()) { |
1168 |
tim |
1.1 |
r.run(); |
1169 |
|
|
} |
1170 |
|
|
} |
1171 |
|
|
} |
1172 |
|
|
|
1173 |
|
|
/** |
1174 |
dl |
1.8 |
* A handler for unexecutable tasks that throws a |
1175 |
|
|
* <tt>RejectedExecutionException</tt>. |
1176 |
tim |
1.1 |
*/ |
1177 |
dl |
1.2 |
public static class AbortPolicy implements RejectedExecutionHandler { |
1178 |
tim |
1.1 |
|
1179 |
|
|
/** |
1180 |
|
|
* Constructs a <tt>AbortPolicy</tt>. |
1181 |
|
|
*/ |
1182 |
|
|
public AbortPolicy() { } |
1183 |
|
|
|
1184 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1185 |
|
|
throw new RejectedExecutionException(); |
1186 |
tim |
1.1 |
} |
1187 |
|
|
} |
1188 |
|
|
|
1189 |
|
|
/** |
1190 |
|
|
* A handler for unexecutable tasks that waits until the task can be |
1191 |
|
|
* submitted for execution. |
1192 |
|
|
*/ |
1193 |
dl |
1.2 |
public static class WaitPolicy implements RejectedExecutionHandler { |
1194 |
tim |
1.1 |
/** |
1195 |
|
|
* Constructs a <tt>WaitPolicy</tt>. |
1196 |
|
|
*/ |
1197 |
|
|
public WaitPolicy() { } |
1198 |
|
|
|
1199 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1200 |
|
|
if (!e.isShutdown()) { |
1201 |
|
|
try { |
1202 |
|
|
e.getQueue().put(r); |
1203 |
tim |
1.14 |
} catch (InterruptedException ie) { |
1204 |
dl |
1.2 |
Thread.currentThread().interrupt(); |
1205 |
|
|
throw new RejectedExecutionException(ie); |
1206 |
|
|
} |
1207 |
tim |
1.1 |
} |
1208 |
|
|
} |
1209 |
|
|
} |
1210 |
|
|
|
1211 |
|
|
/** |
1212 |
|
|
* A handler for unexecutable tasks that silently discards these tasks. |
1213 |
|
|
*/ |
1214 |
dl |
1.2 |
public static class DiscardPolicy implements RejectedExecutionHandler { |
1215 |
tim |
1.1 |
|
1216 |
|
|
/** |
1217 |
|
|
* Constructs <tt>DiscardPolicy</tt>. |
1218 |
|
|
*/ |
1219 |
|
|
public DiscardPolicy() { } |
1220 |
|
|
|
1221 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1222 |
tim |
1.1 |
} |
1223 |
|
|
} |
1224 |
|
|
|
1225 |
|
|
/** |
1226 |
dl |
1.8 |
* A handler for unexecutable tasks that discards the oldest |
1227 |
|
|
* unhandled request. |
1228 |
tim |
1.1 |
*/ |
1229 |
dl |
1.2 |
public static class DiscardOldestPolicy implements RejectedExecutionHandler { |
1230 |
tim |
1.1 |
/** |
1231 |
dl |
1.2 |
* Constructs a <tt>DiscardOldestPolicy</tt> for the given executor. |
1232 |
tim |
1.1 |
*/ |
1233 |
|
|
public DiscardOldestPolicy() { } |
1234 |
|
|
|
1235 |
dl |
1.2 |
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { |
1236 |
|
|
if (!e.isShutdown()) { |
1237 |
|
|
e.getQueue().poll(); |
1238 |
|
|
e.execute(r); |
1239 |
tim |
1.1 |
} |
1240 |
|
|
} |
1241 |
|
|
} |
1242 |
|
|
} |