yanze chen created IOTDB-5471:
---------------------------------
Summary: Add isDone() check in
WrappedThreadPoolExecutor#afterExecute
Key: IOTDB-5471
URL: https://issues.apache.org/jira/browse/IOTDB-5471
Project: Apache IoTDB
Issue Type: Improvement
Reporter: yanze chen
Assignee: yanze chen
I want to use the thread pool created by the IoTDBThreadPoolFactory in
CompleteFuture. However, I have found that this can cause problems with threads
not being released.
Here is the example code.
{code:java}
import org.apache.iotdb.commons.concurrent.IoTDBThreadPoolFactory;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
public class Tests {
public static void main(String[] args) {
ExecutorService flushTaskExecutor1 =
IoTDBThreadPoolFactory.newFixedThreadPool(2, "1");
CompletableFuture<Void>[] completableFutures = new CompletableFuture[5];
for (int j = 0; j < 5; j++) {
completableFutures[j] =
CompletableFuture.supplyAsync(
() -> {
System.out.println("run");
return null;
},
flushTaskExecutor1);
}
CompletableFuture.allOf(completableFutures).join();
System.out.println("done");
flushTaskExecutor1.shutdown();
}
}
{code}
Only two “run” are printed, whereas the expectation is that 5 “run” should be
printed. if I change the thread creation code to
{code:java}
ExecutorService flushTaskExecutor1 = Executors.newFixedThreadPool(2); {code}
, it works as expected.
Using the thread dump, I found that the thread was blocking at
WrappedThreadPoolExecutor#afterExecute after execution. This was due to a
problem with the implementation of CompleteFuture#AsyncRun. One solution I
found in
[https://stackoverflow.com/questions/2248131/handling-exceptions-from-java-executorservice-tasks]
is to add the isDone check before invoking get(). The {{isDone()}} check is
necessary in certain cases to avoid blocking. See
[bugs.openjdk.org/browse/JDK-8071638|https://bugs.openjdk.org/browse/JDK-8071638]
and
[bugs.openjdk.org/browse/JDK-7146994|https://bugs.openjdk.org/browse/JDK-7146994]
for details.
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