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https://issues.apache.org/jira/browse/FLINK-16510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17164511#comment-17164511
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Thomas Weise commented on FLINK-16510:
--------------------------------------

I think there are 2 interests involved here:

1. How to ensure that the task manager JVM gets safely terminated on a fatal 
error, regardless of the behavior of user code and other dependencies
2. Why execution of shutdown hooks can cause the JVM to get stuck

We at Lyft need the option to safely terminate the VMs so that pods are 
replaced immediately. We are not interested in executing of shutdown hooks when 
the JVM is already in a problematic state.

> Task manager safeguard shutdown may not be reliable
> ---------------------------------------------------
>
>                 Key: FLINK-16510
>                 URL: https://issues.apache.org/jira/browse/FLINK-16510
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Task
>            Reporter: Maximilian Michels
>            Assignee: Maximilian Michels
>            Priority: Major
>         Attachments: stack2-1.txt
>
>
> The {{JvmShutdownSafeguard}} does not always succeed but can hang when 
> multiple threads attempt to shutdown the JVM. Apparently mixing 
> {{System.exit()}} with ShutdownHooks and forcefully terminating the JVM via 
> {{Runtime.halt()}} does not play together well:
> {noformat}
> "Jvm Terminator" #22 daemon prio=5 os_prio=0 tid=0x00007fb8e82f2800 
> nid=0x5a96 runnable [0x00007fb35cffb000]
>    java.lang.Thread.State: RUNNABLE
>       at java.lang.Shutdown.$$YJP$$halt0(Native Method)
>       at java.lang.Shutdown.halt0(Shutdown.java)
>       at java.lang.Shutdown.halt(Shutdown.java:139)
>       - locked <0x000000047ed67638> (a java.lang.Shutdown$Lock)
>       at java.lang.Runtime.halt(Runtime.java:276)
>       at 
> org.apache.flink.runtime.util.JvmShutdownSafeguard$DelayedTerminator.run(JvmShutdownSafeguard.java:86)
>       at java.lang.Thread.run(Thread.java:748)
>    Locked ownable synchronizers:
>       - None
> "FlinkCompletableFutureDelayScheduler-thread-1" #18154 daemon prio=5 
> os_prio=0 tid=0x00007fb708a7d000 nid=0x5a8a waiting for monitor entry 
> [0x00007fb289d49000]
>    java.lang.Thread.State: BLOCKED (on object monitor)
>       at java.lang.Shutdown.halt(Shutdown.java:139)
>       - waiting to lock <0x000000047ed67638> (a java.lang.Shutdown$Lock)
>       at java.lang.Shutdown.exit(Shutdown.java:213)
>       - locked <0x000000047edb7348> (a java.lang.Class for java.lang.Shutdown)
>       at java.lang.Runtime.exit(Runtime.java:110)
>       at java.lang.System.exit(System.java:973)
>       at 
> org.apache.flink.runtime.taskexecutor.TaskManagerRunner.terminateJVM(TaskManagerRunner.java:266)
>       at 
> org.apache.flink.runtime.taskexecutor.TaskManagerRunner.lambda$onFatalError$1(TaskManagerRunner.java:260)
>       at 
> org.apache.flink.runtime.taskexecutor.TaskManagerRunner$$Lambda$27464/1464672548.accept(Unknown
>  Source)
>       at 
> java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:774)
>       at 
> java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:750)
>       at 
> java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:488)
>       at 
> java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:1990)
>       at 
> org.apache.flink.runtime.concurrent.FutureUtils$Timeout.run(FutureUtils.java:943)
>       at 
> org.apache.flink.runtime.concurrent.DirectExecutorService.execute(DirectExecutorService.java:211)
>       at 
> org.apache.flink.runtime.concurrent.FutureUtils.lambda$orTimeout$11(FutureUtils.java:361)
>       at 
> org.apache.flink.runtime.concurrent.FutureUtils$$Lambda$27435/159015392.run(Unknown
>  Source)
>       at 
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
>       at java.util.concurrent.FutureTask.run(FutureTask.java:266)
>       at 
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
>       at 
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
>       at 
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
>       at 
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
>       at java.lang.Thread.run(Thread.java:748)
>    Locked ownable synchronizers:
>       - <0x00000006d5e56bd0> (a 
> java.util.concurrent.ThreadPoolExecutor$Worker)
> {noformat}
> Note that under this condition the JVM should terminate but it still hangs. 
> Sometimes it quits after several minutes.



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