java 在关闭 Executor 之前等待所有线程完成
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Waiting for all the threads to finish before shutting down the Executors
提问by Kraken
Here is my code snippet.
这是我的代码片段。
ExecutorService executor = Executors.newFixedThreadPool(ThreadPoolSize);
while(conditionTrue)
{
ClassImplementingRunnable c = new ClassImplementingRunnable();
executor.submit(c);
}
Now after this is do
现在这样做之后
executor.shutdown();
What i want to achieve here is that i want to wait for all the threads in the threadpool to have finished the execution and then i want to shutdown the executor.
我想在这里实现的是，我想等待线程池中的所有线程完成执行，然后我想关闭执行程序。
But i guess this is not what is happening here. The main thread seems to be executing shutdown and it just shuts down everything.
但我想这不是这里发生的事情。主线程似乎正在执行关闭，它只是关闭了一切。
Before when my threadpool size was 2, i did the following and it seemed to work.
在我的线程池大小为 2 之前，我执行了以下操作并且它似乎有效。
ClassImplementingRunnable c1 = new ClassImplementingRunnable();
executor.submit(c1);
ClassImplementingRunnable c2 = new ClassImplementingRunnable();
executor.submit(c2);
Future f1 = executor.submit(c1);
Future f2 = executor.submit(c2);
while(!f1.done || !f2.done)
{}
executor.submit();
How do i do this for a greater number of threads in the threadpool? Thanks.
我如何为线程池中的更多线程执行此操作？谢谢。
回答by assylias
You generally use the following idiom:
您通常使用以下习语：
executor.shutdown();
executor.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS);
shutdownjust says that the executor won't accept new jobs.awaitTerminationwaits until all the tasks that have already been submitted finish what they are doing (or until the timeout is reached - which won't happen with Integer.MAX_VALUE - you might want to use a lower value).
shutdown只是说执行人不会接受新工作。awaitTermination等待所有已经提交的任务完成他们正在做的事情（或者直到超时 - 这不会发生在 Integer.MAX_VALUE - 你可能想要使用一个较低的值）。
回答by Marko Topolnik
shutdownis a "soft" order and won't abruptly shut down the executor. It will do just what you want: refuse any new tasks, wait for all submitted tasks to complete, and then shut down.
shutdown是一个“软”命令，不会突然关闭执行程序。它会做你想做的事：拒绝任何新任务，等待所有提交的任务完成，然后关闭。
Add awaitTerminationto your code in order to block until the executor service is shut down.
添加awaitTermination到您的代码中以阻止直到执行程序服务关闭。
In the documentationthere's also this code that covers all the angles:
在文档中还有这段代码涵盖了所有的角度：
void shutdownAndAwaitTermination(ExecutorService pool) {
pool.shutdown(); // Disable new tasks from being submitted
try {
// Wait a while for existing tasks to terminate
if (!pool.awaitTermination(60, TimeUnit.SECONDS)) {
pool.shutdownNow(); // Cancel currently executing tasks
// Wait a while for tasks to respond to being cancelled
if (!pool.awaitTermination(60, TimeUnit.SECONDS))
System.err.println("Pool did not terminate");
}
} catch (InterruptedException ie) {
// (Re-)Cancel if current thread also interrupted
pool.shutdownNow();
// Preserve interrupt status
Thread.currentThread().interrupt();
}
}
回答by Peter Lawrey
What i want to achieve here is that i want to wait for all the threads in the threadpool to have finished the execution and then i want to shutdown the executor.
我想在这里实现的是，我想等待线程池中的所有线程完成执行，然后我想关闭执行程序。
That is what executor.shutdown();does. If you want to shutdown immediately you need to use shutdownNow()
这就是executor.shutdown();它的作用。如果你想立即关机，你需要使用shutdownNow()
