[FIXED] Spring boot DelegatingSecurityContextAsyncTaskExecutor causes potential memory leak

Issue

In a spring boot app (2.1.4-RELEASE) when using the following configuration of a TaskExecutor

  @Primary
  @Qualifier("threadPoolTaskExecutor")
  @Bean
  public TaskExecutor threadPoolTaskExecutor() {
    final ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(10);
    executor.setMaxPoolSize(100);
    executor.setQueueCapacity(50);
    executor.setThreadNamePrefix("Foo-");
    executor.initialize();

    return new DelegatingSecurityContextAsyncTaskExecutor(executor);
  }

when shutting down tomcat (9.0.19) I get the following warning.

02-May-2019 10:34:07.384 WARNUNG [main] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [myapp#bar] appears to have started a thread named [Foo-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 [email protected]/jdk.internal.misc.Unsafe.park(Native Method)
 [email protected]/java.util.concurrent.locks.LockSupport.park(LockSupport.java:194)
 [email protected]/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2081)
 [email protected]/java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:433)
 [email protected]/java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1054)
 [email protected]/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1114)
 [email protected]/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
 [email protected]/java.lang.Thread.run(Thread.java:834)

The warning disappears when the DelegatingSecurityContextAsyncTaskExecutor is removed:

  @Primary
  @Qualifier("threadPoolTaskExecutor")
  @Bean
  public TaskExecutor threadPoolTaskExecutor() {
    final ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(10);
    executor.setMaxPoolSize(100);
    executor.setQueueCapacity(50);
    executor.setThreadNamePrefix("Foo-");
    executor.initialize();

    return executor;
  }

What is the cause? How can that be solved?

Update: I excuse (please don't stone me) but I completely forgot that it is a spring boot app which is being deployed as an exploded war in the tomcat. I now tried as well tomcat version 9.0.17 which is used by Spring 2.1.4.RELEASE but same problem. When starting the spring boot by itself then the problem does not appear.

Update2: Opened a bug

Solution

Was answered by Rob Winch here.

Answered By - Kavau
Answer Checked By - Terry (JavaFixing Volunteer)