英文:
Killing threads from completion service?
问题
问题
我正在使用完成服务（completion service）并创建子线程来执行一些 ETL 操作。当我在我的 IDE 中进行调试，然后停止所有进程时，我注意到仍然有许多僵尸线程在占用我的 CPU。这是因为我没有正确地终止子线程。
最简示例
Future<Boolean> future = completionService.submit(conversionProcessor);
boolean isCompleted = false;
while (!isCompleted && !closed.get()) {
try {
isCompleted = future.get(CONSUMER_HEARTBEAT_INTERVAL,
TimeUnit.SECONDS); // 等待直到心跳间隔超过
if (isCompleted) {
// 在这里执行一些操作
future.cancel(true);
break;
}
} catch (TimeoutException e) {
// 用于保持消费者在集群中活动
consumer.poll(Duration.ofSeconds(CONSUMER_HEARTBEAT_INTERVAL)); // 执行心跳操作
} catch (CancellationException e) {
future.cancel(true);
break;
} catch (InterruptedException e) {
future.cancel(true);
break;
} catch (WakeupException we) {
future.cancel(true);
break;
} catch (Exception e) {
future.cancel(true);
break;
}
想法
基本上，我将我的 Callable<Boolean> 提交给了完成服务。
ExecutorCompletionService<Boolean> completionService = new ExecutorCompletionService<>(
Executors.newSingleThreadExecutor());
如果我停止调试器，这个线程很可能仍在运行。我刚刚添加了 future.cancel(true) 这一部分，似乎已经停止了来自子线程的连续上传文件，但我仍然在活动监视器中看到这些 Java 进程在运行。
我想知道我应该如何考虑这个问题？我想要 Callable<Boolean>，因为它告诉我底层的 ETL 操作是否已经完成（true/false）。
编辑：
实际上，future.cancel 似乎帮助了不少... 这是我应该使用的方法吗？
英文:
Problem
I am using a completion service and spawning child threads to perform some ETL.
As I debug in my IDE and then stop all processes, I notice I still have a bunch of zombie threads killing my CPU. This is due to the fact that I'm not terminating the child threads properly.
Minimum Example
Future<Boolean> future = completionService.submit(conversionProcessor);
boolean isCompleted = false;
while (!isCompleted && !closed.get()) {
try {
isCompleted = future.get(CONSUMER_HEARTBEAT_INTERVAL,
TimeUnit.SECONDS); // Wait until heartbeat interval exceeds
if (isCompleted) {
// do some things here
future.cancel(true);
break;
}
} catch (TimeoutException e) {
// Used to keep consumer alive in the cluster
consumer.poll(Duration.ofSeconds(CONSUMER_HEARTBEAT_INTERVAL)); // does heart-beat
} catch (CancellationException e) {
future.cancel(true);
break;
} catch (InterruptedException e) {
future.cancel(true);
break;
} catch (WakeupException we) {
future.cancel(true);
break;
} catch (Exception e) {
future.cancel(true);
break;
}
Thoughts
Essentially, I submit my Callable<Boolean> to my completion service.
ExecutorCompletionService<Boolean> completionService = new ExecutorCompletionService<>(
Executors.newSingleThreadExecutor());
If I stop the debugger, this thread is presumably still running. I just added this future.cancel(true) piece, which seems to have stopped continuously uploaded files from my child thread, but I still see these java processes running on my activity monitor.
I'm wondering how I should be thinking about this? I want the callable<boolean> as it tells me when the underlying ETL has completed or not (true/false)
edit:
future.cancel actually seems to be helping quite a bit.. Is this what I want to be using?
答案1
得分: 2
完成CompletionService后，您需要关闭底层的执行器，因此需要执行以下操作：
ExecutorService es = Executors.newSingleThreadExecutor();
ExecutorCompletionService<Boolean> completionService = new ExecutorCompletionService<>(es);
在结束时调用：
es.shutdown();
es.awaitTermination(1, TimeUnit.SECONDS);
英文:
Once you are done with your CompletionService you need to shutdown underlying executor so you need to do the following
ExecutorService es = Executors.newSingleThreadExecutor();
ExecutorCompletionService<Boolean> completionService = new ExecutorCompletionService<>(es);
And a the end call
es.shutdown();
es.awaitTermination(1, TimeUnit.SECONDS);
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