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  1. Jenkins
  2. JENKINS-34450

Deadlock between Executor and AsynchronousExecution

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      A deadlock has been observed sporadically during Pipeline-related tests:

      "jenkins.util.Timer [#3]":
  waiting for ownable synchronizer 0x00000006c25235e0, (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync),
  which is held by "Executing ...SomeTest"
"Executing ...SomeTest":
  waiting to lock monitor 0x00007fd8b8004328 (object 0x00000006c254f860, a org.jenkinsci.plugins.workflow.job.WorkflowRun$2),
  which is held by "jenkins.util.Timer [#3]"
"jenkins.util.Timer [#3]":
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000006c25235e0> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireShared(AbstractQueuedSynchronizer.java:967)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireShared(AbstractQueuedSynchronizer.java:1283)
	at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.lock(ReentrantReadWriteLock.java:727)
	at hudson.model.Executor.getCurrentWorkUnit(Executor.java:533)
	at hudson.model.queue.WorkUnitContext.synchronizeEnd(WorkUnitContext.java:141)
	at hudson.model.Executor.finish1(Executor.java:460)
	at hudson.model.Executor.completedAsynchronous(Executor.java:484)
	at jenkins.model.queue.AsynchronousExecution.completed(AsynchronousExecution.java:118)
	- locked <0x00000006c254f860> (a org.jenkinsci.plugins.workflow.job.WorkflowRun$2)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun$3.run(WorkflowRun.java:249)
	- locked <0x00000006c253fc30> (a java.util.concurrent.atomic.AtomicBoolean)
	at ...
"Executing ...SomeTest":
	at jenkins.model.queue.AsynchronousExecution.getExecutor(AsynchronousExecution.java:98)
	- waiting to lock <0x00000006c254f860> (a org.jenkinsci.plugins.workflow.job.WorkflowRun$2)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun$2.interrupt(WorkflowRun.java:234)
	at hudson.model.Executor.interrupt(Executor.java:227)
	at hudson.model.Executor.interrupt(Executor.java:193)
	at hudson.model.Executor.interrupt(Executor.java:187)
	at hudson.model.Executor.interrupt(Executor.java:173)
	at hudson.model.Executor.doStop(Executor.java:867)
	at org.jenkinsci.plugins.workflow.job.WorkflowRun.doStop(WorkflowRun.java:629)
	- locked <0x00000006c24f8f10> (a org.jenkinsci.plugins.workflow.job.WorkflowRun)
	at ...SomeTest

      I think the bug is in core, not WorkflowRun. The timer thread is holding an AsynchronousExecution monitor and waiting for the corresponding Executor read lock. This is entirely happening in core code. The test thread is holding the executor write lock (from doStop) and waiting for the AsynchronousExecution monitor. doStop winds up calling back into AsynchronousExecution.interrupt, which in this case is calling getExecutor, as indeed the Javadoc recommends.

      (The test thread is also holding a lock on the WorkflowRun, and the timer thread a lock on WorkflowRun.completed, both of which are potentially concerning, but these do not seem involved here.)

            jglick Jesse Glick
            jglick Jesse Glick
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              Created:
              Updated: