[jboss-jira] [JBoss JIRA] (WFLY-10621) Server stop indefinitely blocked on by DistributableSessionManager in lifecycleLock.writeLockInterruptibly()

[Petr H (JIRA)]

Petr H created WFLY-10621:
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             Summary: Server stop indefinitely blocked on by DistributableSessionManager in lifecycleLock.writeLockInterruptibly()
                 Key: WFLY-10621
                 URL: https://issues.jboss.org/browse/WFLY-10621
             Project: WildFly
          Issue Type: Bug
          Components: Clustering
    Affects Versions: 11.0.0.Final
         Environment: CentOS 7.4.1708
Java 1.8.0_172-b11
WildFly 11.0.0.Final
            Reporter: Petr H
            Assignee: Paul Ferraro
         Attachments: threaddump-wfly11-stop-blocked.txt

Note: This is report for the issue reported here first https://developer.jboss.org/thread/277883
It can be seen at WildFly 11 and EAP 7.1 at least, however as the particular code in the DistributableSessionManager class seems to be unchanged even in WildFly 13 it's likely to occur there as well. (We test WildFly 11 because it's closest to the EAP 7.1 which is being considered for the production use later in this project)

Stop server operation may hang indefinitely due to the thread such as the following one being blocked:
{noformat}
"ServerService Thread Pool -- 24" #49 prio=5 os_prio=0 tid=0x00000000035d1000 nid=0x4de1 waiting on condition [0x00007f4bddc46000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000c4e61998> (a java.util.concurrent.locks.StampedLock)
        at java.util.concurrent.locks.StampedLock.acquireWrite(StampedLock.java:1119)
        at java.util.concurrent.locks.StampedLock.writeLockInterruptibly(StampedLock.java:413)
        at org.wildfly.clustering.web.undertow.session.DistributableSessionManager.stop(DistributableSessionManager.java:90)
        - locked <0x00000000c4e60090> (a org.wildfly.clustering.web.undertow.session.DistributableSessionManager)
        at io.undertow.servlet.core.DeploymentManagerImpl$3.call(DeploymentManagerImpl.java:599)
        at io.undertow.servlet.core.DeploymentManagerImpl$3.call(DeploymentManagerImpl.java:589)
        at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:42)
        at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
        at org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
        at org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction$$Lambda$1005/749195997.call(Unknown Source)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction$$Lambda$1006/1165195653.call(Unknown Source)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction$$Lambda$1006/1165195653.call(Unknown Source)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction$$Lambda$1006/1165195653.call(Unknown Source)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction$$Lambda$1006/1165195653.call(Unknown Source)
        at io.undertow.servlet.core.DeploymentManagerImpl.stop(DeploymentManagerImpl.java:603)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentService.stopContext(UndertowDeploymentService.java:139)
        at org.wildfly.extension.undertow.deployment.UndertowDeploymentService$2.run(UndertowDeploymentService.java:120)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        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)
        at org.jboss.threads.JBossThread.run(JBossThread.java:320)
{noformat}
The related code in the DistributableSessionManager makes use of the *java.util.concurrent.locks.StampedLock.writeLockInterruptibly* method which can theoretically block indefinitely and thus prevent the server stop from ever completing.

The change was introduced in the following commit [WFLY-7695 Block session manager stop until all sessions are closed|https://github.com/wildfly/wildfly/commit/94863deeb96c4536ec5e8266573e211289b02529#diff-a7519dd56759f6084e7c0c0bb006353f]

This can occur even in non-clustered environments (non-HA profile) with web applications just being marked as distributable (web.xml).

We don't know what prevents the lock from being obtained (unable to determine from the thread dump) so we can't unfortunately do much about it at the moment from the application side.

We only tried to change the infinispan web local-cache configuration due to _ISPN000136_ errors intermittedly occurring, but that seems to have no effect. We tried various combinations of *locking isolation* (REPEATABLE_READ, READ_COMMITED), *transaction locking* (OPTIMISTIC, PESSIMISTIC) and *transaction mode* (NONE, BATCH) settings and it seems to occur with all of them.

Note: The issue doesn't occur always, only in some cases.



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