I'm currently in the process of evaluating milo for our project. One thing I noticed while shutting down our application is that milo seems to have some trouble shutting down all of its worker threads.
Here's how I tried to shutdown milo:
OpcUaClient _client;
//connect to opc endpoint
.....
//shutting down milo
_client.disconnect().get();
However when I run this code, our application fails to shutdown milo's threads:
WARNUNG: The web application [ROOT] appears to have started a thread named [milo-netty-event-loop-0] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
io.netty.channel.nio.SelectedSelectionKeySetSelector.select(SelectedSelectionKeySetSelector.java:62)
io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:824)
io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:457)
io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1050)
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
java.lang.Thread.run(Thread.java:748)
Okt 01, 2020 11:23:35 AM org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
WARNUNG: The web application [ROOT] appears to have started a thread named [milo-netty-wheel-timer] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.lang.Thread.sleep(Native Method)
io.netty.util.HashedWheelTimer$Worker.waitForNextTick(HashedWheelTimer.java:577)
io.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:476)
java.lang.Thread.run(Thread.java:748)
Okt 01, 2020 11:23:35 AM org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
WARNUNG: The web application [ROOT] appears to have started a thread named [milo-netty-event-loop-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
io.netty.channel.nio.SelectedSelectionKeySetSelector.select(SelectedSelectionKeySetSelector.java:62)
io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:824)
io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:457)
io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1050)
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
java.lang.Thread.run(Thread.java:748)
Okt 01, 2020 11:23:35 AM org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
WARNUNG: The web application [ROOT] appears to have started a thread named [milo-shared-scheduled-executor-0] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
sun.misc.Unsafe.park(Native Method)
java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1081)
java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
java.lang.Thread.run(Thread.java:748)
I always assumed that this would shutdown milo and its worker threads. Is there something I'm missing? I looked through the javadoc but couldn't find anything concrete about shutting down milos worker threads.
Kind regards,
