Jenkins slaves hanging/Jenkins wedged - jenkins

Question

We have an intermittent problem with slaves hanging AFTER the job itself is finished. In the post processing step (?) what we see is that the console log has this line:
Description set: vap_current_iter-2012_03_29_19_01_03
And then nothing. Usually, it will look like this:
Description set: prod_pull-2012_03_28_19_01_03
Notifying upstream build armada_Launch_prod_pull #13 of job completion
Project armada_Launch_prod_pull still waiting for 1 builds to complete
Notifying upstream projects of job completion
Notifying upstream of completion: armada_Launch_prod_pull #13
Finished: SUCCESS
I setup a logger for hudson.model.Run, and it currently has this :
at java.lang.Thread.run(Thread.java:619)
Mar 30, 2012 12:44:00 PM hudson.model.Run run
INFO: galleon_allUnit #1134 main build action completed: SUCCESS
Mar 30, 2012 12:44:00 PM hudson.model.Run setResult
FINE: galleon_allUnit #1134 : result is set to SUCCESS
java.lang.Exception
at hudson.model.Run.setResult(Run.java:352)
at hudson.model.Run.run(Run.java:1410)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:238)
Repeated for every hung slave.
The main hudson log doesn't have any additional information.
Disconnecting the slave has no effect.
Trying to do an orderly shutdown of Jenkins has no effect (jenkins actually appears to hang on shutdown).
The only way we have found to recover is to kill -9 the tomcat process.
The tread dump for one of the slaves (they are all the same) is:
Thread Dump
Channel reader thread: channel
"Channel reader thread: channel" Id=9 Group=main RUNNABLE (in native)
at java.io.FileInputStream.readBytes(Native Method)
at java.io.FileInputStream.read(FileInputStream.java:199)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
at java.io.BufferedInputStream.read(BufferedInputStream.java:237)
- locked java.io.BufferedInputStream#1ae615a
at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249)
at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542)
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
at hudson.remoting.Channel$ReaderThread.run(Channel.java:1030)
main
"main" Id=1 Group=main WAITING on hudson.remoting.Channel#e1d5ea
at java.lang.Object.wait(Native Method)
- waiting on hudson.remoting.Channel#e1d5ea
at java.lang.Object.wait(Object.java:485)
at hudson.remoting.Channel.join(Channel.java:766)
at hudson.remoting.Launcher.main(Launcher.java:420)
at hudson.remoting.Launcher.runWithStdinStdout(Launcher.java:366)
at hudson.remoting.Launcher.run(Launcher.java:206)
at hudson.remoting.Launcher.main(Launcher.java:168)
Ping thread for channel hudson.remoting.Channel#e1d5ea:channel
"Ping thread for channel hudson.remoting.Channel#e1d5ea:channel" Id=10 Group=main TIMED_WAITING
at java.lang.Thread.sleep(Native Method)
at hudson.remoting.PingThread.run(PingThread.java:86)
Pipe writer thread: channel
"Pipe writer thread: channel" Id=12 Group=main WAITING on java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject#14263ed
at sun.misc.Unsafe.park(Native Method)
- waiting on java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject#14263ed
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1925)
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:358)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:947)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
pool-1-thread-267
"pool-1-thread-267" Id=285 Group=main RUNNABLE
at sun.management.ThreadImpl.dumpThreads0(Native Method)
at sun.management.ThreadImpl.dumpAllThreads(ThreadImpl.java:374)
at hudson.Functions.getThreadInfos(Functions.java:872)
at hudson.util.RemotingDiagnostics$GetThreadDump.call(RemotingDiagnostics.java:93)
at hudson.util.RemotingDiagnostics$GetThreadDump.call(RemotingDiagnostics.java:89)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:287)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Number of locked synchronizers = 1
- java.util.concurrent.locks.ReentrantLock$NonfairSync#1186f88
Finalizer
"Finalizer" Id=3 Group=system WAITING on java.lang.ref.ReferenceQueue$Lock#1798fdd
at java.lang.Object.wait(Native Method)
- waiting on java.lang.ref.ReferenceQueue$Lock#1798fdd
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)
Reference Handler
"Reference Handler" Id=2 Group=system WAITING on java.lang.ref.Reference$Lock#1d40442
at java.lang.Object.wait(Native Method)
- waiting on java.lang.ref.Reference$Lock#1d40442
at java.lang.Object.wait(Object.java:485)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
Signal Dispatcher
"Signal Dispatcher" Id=4 Group=system RUNNABLE
Any ideas on how to better recover or prevent this would be greatly appreciated.

Answer 1

We honestly just wrote a script that restarts jenkins every night at 4pm. We found that our breakages were happening at 3am give or take a half hour or so. Since restarting the server at this time, we haven't seen any further hangs. This is a way to prevent it as you asked, though it doesn't "Fix" the problem obviously!