JBoss deadlocks and hangs accessing synchronized Seam components

Solution Verified - Updated

Environment

  • JBoss Enterprise Application Platform (EAP)
    • Seam

Issue

  • JBoss hangs due to threads that are deadlocked on synchronized Seam components, like so:
    "ajp-0.0.0.0-8009-1" daemon prio=10 tid=0x000000004b8c4800 nid=0x350c waiting on condition [0x0000000061778000]
   java.lang.Thread.State: TIMED_WAITING (parking)
     at sun.misc.Unsafe.park(Native Method)
     - parking to wait for  <0x0000000774430a88> (a java.util.concurrent.locks.ReentrantLock$FairSync)
     at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198)
     at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireNanos(AbstractQueuedSynchronizer.java:905)
     at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireNanos(AbstractQueuedSynchronizer.java:1224)
     at java.util.concurrent.locks.ReentrantLock.tryLock(ReentrantLock.java:416)
     at org.jboss.seam.core.SynchronizationInterceptor.aroundInvoke(SynchronizationInterceptor.java:28)
     at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
     at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
     at org.jboss.seam.intercept.JavaBeanInterceptor.interceptInvocation(JavaBeanInterceptor.java:185)
     at org.jboss.seam.intercept.JavaBeanInterceptor.invoke(JavaBeanInterceptor.java:103)

Resolution

  • Ensure the Seam components' synchronized timeouts are not set too high.  Usually something around 1 to 5 seconds suffices:
    @Synchronized(timeout=5000)

Root Cause

  • Multiple threads hit the same Seam components at once to cause a deadlock.
  • These components should have a synchronized timeout, meaning this deadlocked state couldn't last any longer than the timeout.
  • If this timeout is set very high, this deadlock can persist for quite some time to back up many threads.

Diagnostic Steps

Product(s)
Components

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