Possible memory leak (org.neo4j.driver.internal.shaded.io.netty.util.ThreadDeathWatcher)

[jastax]

I'm using the 1.5.0 driver / Spring Data Neo4j (5.0.5.RELEASE).
The following error shows up in Eclipse when my application is auto-restarted after changing code.
(I don't have much time to take a deeper look right now.)

Warning: The web application [webapp] appears to have started a thread named [threadDeathWatcher-3-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 java.lang.Thread.sleep(Native Method)
 org.neo4j.driver.internal.shaded.io.netty.util.ThreadDeathWatcher$Watcher.run(ThreadDeathWatcher.java:152)
 org.neo4j.driver.internal.shaded.io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
 java.lang.Thread.run(Thread.java:745)
Mär 28, 2018 11:06:24 AM org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
WARNUNG: The web application [intranetrepository] appears to have started a thread named [globalEventExecutor-1-3] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 sun.misc.Unsafe.park(Native Method)
 java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
 java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
 java.util.concurrent.LinkedBlockingQueue.poll(LinkedBlockingQueue.java:467)
 org.neo4j.driver.internal.shaded.io.netty.util.concurrent.GlobalEventExecutor.takeTask(GlobalEventExecutor.java:90)
 org.neo4j.driver.internal.shaded.io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run(GlobalEventExecutor.java:230)
 org.neo4j.driver.internal.shaded.io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
 java.lang.Thread.run(Thread.java:745)

[lutovich]

Hi @querynaut,

Thanks for reporting this problem.
Driver 1.5.0 uses a slightly outdated Netty version where ThreadDeathWatcher and GlobalEventExecutor threads might hold onto class loaders. See netty/netty#7290 for more details.

PR #479 upgrades Netty version to one containing the fix. Upgrade is in 1.6 branch and should be available with next 1.6 alpha release and then in 1.6.0 GA.