Java 如果我叫return怎么办;从Runnable开始?
我在Java Runnable中实现了Java 如果我叫return怎么办;从Runnable开始?,java,multithreading,executorservice,Java,Multithreading,Executorservice,我在Java Runnable中实现了run()方法。在这个run方法中有一些到服务器的连接,当它失败时,我对线程执行不再感兴趣,我想退出它。我是这样做的: class MyRunnable implements Runnable { @Override public void run() { // connect to server here if (it failed) { return; }
run()
方法。在这个run方法中有一些到服务器的连接,当它失败时,我对线程执行不再感兴趣,我想退出它。我是这样做的:
class MyRunnable implements Runnable {
@Override
public void run() {
// connect to server here
if (it failed) {
return;
}
// do something else
}
}
现在,我使用自己的线程工厂将此runnable提交到Executors.cachedThreadPool(),它基本上没有什么新功能
我能安全地从那样的地方回来吗
我查看了jvisualvm,我看到线程池中有一个线程+有一些线程在与服务器逻辑的连接中执行,当我返回时,我看到这些连接线程被停止,它们确实保留在列表中,但它们是白色的 从
void
方法使用return
是非常好的。它只是从该方法返回,在本例中,该方法将完成线程执行。从void
方法使用return
是完全正确的。它只是从该方法返回,在本例中,该方法将完成线程执行。您不是向执行器提交线程,而是向其提交可运行文件。在Runnable中调用return不会导致执行它的线程终止。编写executor是为了在Runnable完成执行(不管它是否提前返回)后,线程继续执行,并从排队提交的任务中获得更多的工作,它可以以Runnable的形式运行多个任务
以下是ThreadPoolExecutor#runWorker方法中的代码。显示task.run()
的行是工作线程执行任务的位置,当您的任务返回时,工作线程将从那里继续执行
final void runWorker(Worker w) {
Thread wt = Thread.currentThread();
Runnable task = w.firstTask;
w.firstTask = null;
w.unlock(); // allow interrupts
boolean completedAbruptly = true;
try {
while (task != null || (task = getTask()) != null) {
w.lock();
// If pool is stopping, ensure thread is interrupted;
// if not, ensure thread is not interrupted. This
// requires a recheck in second case to deal with
// shutdownNow race while clearing interrupt
if ((runStateAtLeast(ctl.get(), STOP) ||
(Thread.interrupted() &&
runStateAtLeast(ctl.get(), STOP))) &&
!wt.isInterrupted())
wt.interrupt();
try {
beforeExecute(wt, task);
Throwable thrown = null;
try {
task.run();
} catch (RuntimeException x) {
thrown = x; throw x;
} catch (Error x) {
thrown = x; throw x;
} catch (Throwable x) {
thrown = x; throw new Error(x);
} finally {
afterExecute(task, thrown);
}
} finally {
task = null;
w.completedTasks++;
w.unlock();
}
}
completedAbruptly = false;
} finally {
processWorkerExit(w, completedAbruptly);
}
}
您不是向执行器提交线程,而是向其提交可运行程序。在Runnable中调用return不会导致执行它的线程终止。编写executor是为了在Runnable完成执行(不管它是否提前返回)后,线程继续执行,并从排队提交的任务中获得更多的工作,它可以以Runnable的形式运行多个任务 以下是ThreadPoolExecutor#runWorker方法中的代码。显示
task.run()
的行是工作线程执行任务的位置,当您的任务返回时,工作线程将从那里继续执行
final void runWorker(Worker w) {
Thread wt = Thread.currentThread();
Runnable task = w.firstTask;
w.firstTask = null;
w.unlock(); // allow interrupts
boolean completedAbruptly = true;
try {
while (task != null || (task = getTask()) != null) {
w.lock();
// If pool is stopping, ensure thread is interrupted;
// if not, ensure thread is not interrupted. This
// requires a recheck in second case to deal with
// shutdownNow race while clearing interrupt
if ((runStateAtLeast(ctl.get(), STOP) ||
(Thread.interrupted() &&
runStateAtLeast(ctl.get(), STOP))) &&
!wt.isInterrupted())
wt.interrupt();
try {
beforeExecute(wt, task);
Throwable thrown = null;
try {
task.run();
} catch (RuntimeException x) {
thrown = x; throw x;
} catch (Error x) {
thrown = x; throw x;
} catch (Throwable x) {
thrown = x; throw new Error(x);
} finally {
afterExecute(task, thrown);
}
} finally {
task = null;
w.completedTasks++;
w.unlock();
}
}
completedAbruptly = false;
} finally {
processWorkerExit(w, completedAbruptly);
}
}
是的,它只是一个方法调用。返回很好。是的,它只是一个方法调用。回来很好。是的,你是对的。我对此进行了测试,runnable过早地返回了几次,并且在JVM的整个生命周期中,jvisualvm中仍然有一个线程处于活动状态,因此在空闲时可以重用线程。是的,你是对的。我对此进行了测试,runnable过早地返回了几次,并且在JVM的整个生命周期中,jvisualvm中仍然有一个线程处于活动状态,因此线程在空闲时被重用。