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Zookeeper >> mail # user >> identify the cause of a large quantity of zookeeper threads


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identify the cause of a large quantity of zookeeper threads
I am trying to debug a problem in which when I run jstack, I see a very
large number of zookeeper threads, and as the program continues running,
more threads like the following are created. I suspect somewhere in the
program it is not releasing some resource properly, but I am not sure where
it is.

What would be the cause of these threads waiting? Are they created by
launching new instances of zookeeper, or created by read/write operations?

Thanks.
"main-EventThread" daemon prio=5 tid=7fbf2f71d800 nid=0x11c4e4000 waiting
on condition [11c4e3000]
   java.lang.Thread.State: WAITING (parking)
 at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <77e5838b8> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
 at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1987)
 at
java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:399)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:493)

"main-SendThread(localhost:21819)" daemon prio=5 tid=7fbf2f651800
nid=0x11c3e1000 runnable [11c3e0000]
   java.lang.Thread.State: RUNNABLE
at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
 at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:136)
at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:69)
 at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
- locked <77e582700> (a sun.nio.ch.Util$2)
 - locked <77e5826f0> (a java.util.Collections$UnmodifiableSet)
- locked <77e5824e8> (a sun.nio.ch.KQueueSelectorImpl)
 at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
at
org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:274)
 at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1035)

"main-EventThread" daemon prio=5 tid=7fbf2f64f800 nid=0x11c0a7000 waiting
on condition [11c0a6000]
   java.lang.Thread.State: WAITING (parking)
 at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <77e39be90> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
 at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1987)
 at
java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:399)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:493)

"main-SendThread(localhost:21819)" daemon prio=5 tid=7fbf2f0b6000
nid=0x11b7d2000 runnable [11b7d1000]
   java.lang.Thread.State: RUNNABLE
at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
 at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:136)
at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:69)
 at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
- locked <77e39acd8> (a sun.nio.ch.Util$2)
 - locked <77e39acc8> (a java.util.Collections$UnmodifiableSet)
- locked <77e39aac0> (a sun.nio.ch.KQueueSelectorImpl)
 at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
at
org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:274)
 at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1035)

"main-EventThread" daemon prio=5 tid=7fbf2f0b5000 nid=0x117c9e000 waiting
on condition [117c9d000]
   java.lang.Thread.State: WAITING (parking)
 at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <77dfd9540> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
 at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1987)
 at
java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:399)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:493)

"main-SendThread(localhost:21819)" daemon prio=5 tid=7fbf2f6b4000
nid=0x1174b6000 runnable [1174b5000]
   java.lang.Thread.State: RUNNABLE
at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
 at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:136)
at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:69)
 at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
- locked <77dfd83c8> (a sun.nio.ch.Util$2)
 - locked <77dfd83b8> (a java.util.Collections$UnmodifiableSet)
- locked <77dfd81b0> (a sun.nio.ch.KQueueSelectorImpl)
 at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
at
org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:274)
 at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1035)
+
Camille Fournier 2012-10-03, 19:24