我需要一次执行一定数量的任务4，就像这样:
ExecutorService taskExecutor = Executors.newFixedThreadPool(4);
while(...) {
taskExecutor.execute(new MyTask());
}
//...wait for completion somehow
当所有这些都完成后，我如何得到通知?现在我想不出比设置一些全局任务计数器更好的方法，并在每个任务结束时减少它，然后在无限循环中监视这个计数器变成0;或获取一个期货列表，并在无限循环监视器isDone为所有它们。不涉及无限循环的更好的解决方案是什么?
谢谢。
当前回答
所以我把我的答案贴在这里，以防有人想要一个更简单的方法来做到这一点
ExecutorService executor = Executors.newFixedThreadPool(10);
CompletableFuture[] futures = new CompletableFuture[10];
int i = 0;
while (...) {
futures[i++] = CompletableFuture.runAsync(runner, executor);
}
CompletableFuture.allOf(futures).join(); // THis will wait until all future ready.
其他回答
这可能会有所帮助
Log.i(LOG_TAG, "shutting down executor...");
executor.shutdown();
while (true) {
try {
Log.i(LOG_TAG, "Waiting for executor to terminate...");
if (executor.isTerminated())
break;
if (executor.awaitTermination(5000, TimeUnit.MILLISECONDS)) {
break;
}
} catch (InterruptedException ignored) {}
}
如果你连续使用了更多的ExecutionServices线程，并且想要等待每个EXECUTIONSERVICE完成。最好的办法是像下面这样;
ExecutorService executer1 = Executors.newFixedThreadPool(THREAD_SIZE1);
for (<loop>) {
executer1.execute(new Runnable() {
@Override
public void run() {
...
}
});
}
executer1.shutdown();
try{
executer1.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
ExecutorService executer2 = Executors.newFixedThreadPool(THREAD_SIZE2);
for (true) {
executer2.execute(new Runnable() {
@Override
public void run() {
...
}
});
}
executer2.shutdown();
} catch (Exception e){
...
}
基本上在ExecutorService上调用shutdown()，然后调用awaitterminate ():
ExecutorService taskExecutor = Executors.newFixedThreadPool(4);
while(...) {
taskExecutor.execute(new MyTask());
}
taskExecutor.shutdown();
try {
taskExecutor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
} catch (InterruptedException e) {
...
}
遵循以下方法之一。
遍历从ExecutorService上的submit返回的所有Future任务，并按照Kiran的建议使用Future对象上的阻塞调用get()检查状态 在ExecutorService上使用invokeAll() CountDownLatch ForkJoinPool或Executors.html#newWorkStealingPool 按照适当的顺序使用ThreadPoolExecutor的shutdown、awaitterminate、shutdownNow api
相关的SE问题:
CountDownLatch是如何在Java多线程中使用的?
如何正确关闭java ExecutorService
你应该使用executorService.shutdown()和executorService。awaitTermination方法。
示例如下:
public class ScheduledThreadPoolExample {
public static void main(String[] args) throws InterruptedException {
ScheduledExecutorService executorService = Executors.newScheduledThreadPool(5);
executorService.scheduleAtFixedRate(() -> System.out.println("process task."),
0, 1, TimeUnit.SECONDS);
TimeUnit.SECONDS.sleep(10);
executorService.shutdown();
executorService.awaitTermination(1, TimeUnit.DAYS);
}
}
