我使用以下代码创建了一个ThreadPoolExecutor:
private ExecutorService executor = new ThreadPoolExecutor(5, 10, 120, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(20, true));
然后,我运行了25个任务(T01到T25),情况如下:
- 5个任务正在运行中(T01到T05)
- 20个任务在队列中等待(T06到T25)
但是,在现实生活中,如果队列已满且尚未达到MaxPoolSize限制,则会启动最新的任务。
所以,我有...
- 6个任务正在运行中(T01到T05和T26)
- 20个任务在队列中等待(T06到T25)
- 6个任务正在运行中(T01到T06)
- 20个任务在队列中等待(T07到T26)
顺便提一下,这是ThreadPoolExecutor源代码的一部分。
public void execute(Runnable command) {
if (command == null)
throw new NullPointerException();
if (poolSize >= corePoolSize || !addIfUnderCorePoolSize(command)) {
if (runState == RUNNING && workQueue.offer(command)) {
if (runState != RUNNING || poolSize == 0)
ensureQueuedTaskHandled(command);
}
else if (!addIfUnderMaximumPoolSize(command))
reject(command); // is shutdown or saturated
}
}
private boolean addIfUnderMaximumPoolSize(Runnable firstTask) {
Thread t = null;
final ReentrantLock mainLock = this.mainLock;
mainLock.lock();
try {
if (poolSize < maximumPoolSize && runState == RUNNING)
t = addThread(firstTask);
} finally {
mainLock.unlock();
}
if (t == null)
return false;
t.start();
return true;
}
谢谢