Java ExecutorService.submit如何提交工作
我试图了解Executor.submit(Runnable)是如何工作的。假设我们使用ExecutorService创建一个大小为2的线程池 我们有一个名为Runner implements Runnable的类Java ExecutorService.submit如何提交工作,java,multithreading,Java,Multithreading,我试图了解Executor.submit(Runnable)是如何工作的。假设我们使用ExecutorService创建一个大小为2的线程池 我们有一个名为Runner implements Runnable的类 ExecutorService.newFixedThreadPool(2); for (int i = 0; i <5; i++){ ExecutorService.submit(new Runner()); } ExecutorService.newFixedThread
ExecutorService.newFixedThreadPool(2);
for (int i = 0; i <5; i++){
ExecutorService.submit(new Runner());
}
ExecutorService.newFixedThreadPool(2);
对于(int i=0;i,服务使用一个队列来存储传入的可运行对象。一旦有线程可用于执行工作,服务就会使用该线程来执行下一个到期的可运行对象
可运行程序是而不是线程。您的示例将创建组成池的两个线程;然后随着时间的推移,5个运行程序对象将被分派到这两个线程中的一个
这就是它的全部内容。不,您正在创建包含2个线程的线程池,Executor服务将等到池中有可用线程时,才将下一个任务提交给可用线程。您可以检查from grepcode的实现
AbstractExecutorService
是的基类,它实现
检查工人
在同一类中的实施情况
/**
* Class Worker mainly maintains interrupt control state for
* threads running tasks, along with other minor bookkeeping.
* This class opportunistically extends AbstractQueuedSynchronizer
* to simplify acquiring and releasing a lock surrounding each
* task execution. This protects against interrupts that are
* intended to wake up a worker thread waiting for a task from
* instead interrupting a task being run. We implement a simple
* non-reentrant mutual exclusion lock rather than use ReentrantLock
* because we do not want worker tasks to be able to reacquire the
* lock when they invoke pool control methods like setCorePoolSize.
*/
我明白了!谢谢你的回复。我该怎么做,我没有看到任何扣子。我想它就在那里,只是看得不够锐利:)谢谢你的回复。
public void execute(Runnable command) {
if (command == null)
throw new NullPointerException();
/*
* Proceed in 3 steps:
*
* 1. If fewer than corePoolSize threads are running, try to
* start a new thread with the given command as its first
* task. The call to addWorker atomically checks runState and
* workerCount, and so prevents false alarms that would add
* threads when it shouldn't, by returning false.
*
* 2. If a task can be successfully queued, then we still need
* to double-check whether we should have added a thread
* (because existing ones died since last checking) or that
* the pool shut down since entry into this method. So we
* recheck state and if necessary roll back the enqueuing if
* stopped, or start a new thread if there are none.
*
* 3. If we cannot queue task, then we try to add a new
* thread. If it fails, we know we are shut down or saturated
* and so reject the task.
*/
int c = ctl.get();
if (workerCountOf(c) < corePoolSize) {
if (addWorker(command, true))
return;
c = ctl.get();
}
if (isRunning(c) && workQueue.offer(command)) {
int recheck = ctl.get();
if (! isRunning(recheck) && remove(command))
reject(command);
else if (workerCountOf(recheck) == 0)
addWorker(null, false);
}
else if (!addWorker(command, false))
reject(command);
/**
* Checks if a new worker can be added with respect to current
* pool state and the given bound (either core or maximum). If so,
* the worker count is adjusted accordingly, and, if possible, a
* new worker is created and started running firstTask as its
* first task. This method returns false if the pool is stopped or
* eligible to shut down. It also returns false if the thread
* factory fails to create a thread when asked, which requires a
* backout of workerCount, and a recheck for termination, in case
* the existence of this worker was holding up termination.
*
* @param firstTask the task the new thread should run first (or
* null if none). Workers are created with an initial first task
* (in method execute()) to bypass queuing when there are fewer
* than corePoolSize threads (in which case we always start one),
* or when the queue is full (in which case we must bypass queue).
* Initially idle threads are usually created via
* prestartCoreThread or to replace other dying workers.
*
* @param core if true use corePoolSize as bound, else
* maximumPoolSize. (A boolean indicator is used here rather than a
* value to ensure reads of fresh values after checking other pool
* state).
* @return true if successful
*/
private boolean addWorker(Runnable firstTask, boolean core)
/**
* Class Worker mainly maintains interrupt control state for
* threads running tasks, along with other minor bookkeeping.
* This class opportunistically extends AbstractQueuedSynchronizer
* to simplify acquiring and releasing a lock surrounding each
* task execution. This protects against interrupts that are
* intended to wake up a worker thread waiting for a task from
* instead interrupting a task being run. We implement a simple
* non-reentrant mutual exclusion lock rather than use ReentrantLock
* because we do not want worker tasks to be able to reacquire the
* lock when they invoke pool control methods like setCorePoolSize.
*/