Java thread blocking

Question

i have a problem with my java environement. I'm running Solr 1.3 (search engine) since more then a year now and suddenly i got alot of trouble with it. All my thread pool (250) got randomly blocked once or twice a day. I did not make any change on my solr application or my tomcat server.

I'm running tomcat 5.5.25 and Solr 1.3. I got a thread dump when the system is totally overloaded :

igot like 240 thread like this one :

"http-8080-Processor1" daemon prio=10 tid=0x0000000000b2e000 nid=0x193 waiting for monitor entry [0x000000004066c000..0x000000004066cb20]
   java.lang.Thread.State: BLOCKED (on object monitor)
    at java.util.logging.StreamHandler.publish(StreamHandler.java:174)
    - waiting to lock <0x00007fe37e72b340> (a java.util.logging.ConsoleHandler)
    at java.util.logging.ConsoleHandler.publish(ConsoleHandler.java:88)
    at java.util.logging.Logger.log(Logger.java:472)
    at java.util.logging.Logger.doLog(Logger.java:494)
    at java.util.logging.Logger.log(Logger.java:517)
    at java.util.logging.Logger.info(Logger.java:1036)
    at org.apache.solr.core.SolrCore.execute(SolrCore.java:1212)
    at org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:303)
    at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:232)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Thread.java:619)

We can see that this thread is blocked and waiting on : <0x00007fe37e72b340>

The thread who actually own the <0x00007fe37e72b340> is this one :

"http-8080-Processor156" daemon prio=10 tid=0x0000000000df2000 nid=0x1e52 runnable [0x0000000044521000..0x0000000044521c20]
   java.lang.Thread.State: RUNNABLE
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:260)
    at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105)
    - locked <0x00007fe37e3abcd8> (a java.io.BufferedOutputStream)
    at java.io.PrintStream.write(PrintStream.java:430)
    - locked <0x00007fe37e3abca0> (a java.io.PrintStream)
    at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:202)
    at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:272)
    at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:276)
    at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:122)
    - locked <0x00007fe37e72cd90> (a java.io.OutputStreamWriter)
    at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:212)
    at java.util.logging.StreamHandler.flush(StreamHandler.java:225)
    - locked <0x00007fe37e72b340> (a java.util.logging.ConsoleHandler)
    at java.util.logging.ConsoleHandler.publish(ConsoleHandler.java:89)
    at java.util.logging.Logger.log(Logger.java:472)
    at java.util.logging.Logger.doLog(Logger.java:494)
    at java.util.logging.Logger.log(Logger.java:517)
    at java.util.logging.Logger.info(Logger.java:1036)
    at org.apache.solr.core.SolrCore.execute(SolrCore.java:1212)
    at org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:303)
    at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:232)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Thread.java:619)

and this is the last part of my thread dump :

"ContainerBackgroundProcessor[StandardEngine[Catalina]]" daemon prio=10 tid=0x00007f6510349800 nid=0xbff waiting on condition [0x0000000041d8d000..0x0000000041d8dd20]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
    at java.lang.Thread.sleep(Native Method)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1548)
    at java.lang.Thread.run(Thread.java:619)

"pool-1-thread-1" prio=10 tid=0x0000000000c26400 nid=0xbfe waiting on condition [0x000000004200e000..0x000000004200eca0]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00007f651b275510> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1925)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:358)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:946)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:906)
    at java.lang.Thread.run(Thread.java:619)

"Low Memory Detector" daemon prio=10 tid=0x00007f6510004400 nid=0xbfa runnable [0x0000000000000000..0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"CompilerThread1" daemon prio=10 tid=0x00007f6510001000 nid=0xbf9 waiting on condition [0x0000000000000000..0x0000000040d5e340]
   java.lang.Thread.State: RUNNABLE

"CompilerThread0" daemon prio=10 tid=0x00000000006bc400 nid=0xbf8 waiting on condition [0x0000000000000000..0x0000000040c5d2d0]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" daemon prio=10 tid=0x00000000006bb000 nid=0xbf7 runnable [0x0000000000000000..0x0000000040b5da30]
   java.lang.Thread.State: RUNNABLE

"Finalizer" daemon prio=10 tid=0x0000000000690c00 nid=0xbf6 in Object.wait() [0x000000004065e000..0x000000004065ed20]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    - waiting on <0x00007f651aa10258> (a java.lang.ref.ReferenceQueue$Lock)
    at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116)
    - locked <0x00007f651aa10258> (a java.lang.ref.ReferenceQueue$Lock)
    at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132)
    at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)

"Reference Handler" daemon prio=10 tid=0x000000000068f400 nid=0xbf5 in Object.wait() [0x000000004055d000..0x000000004055dca0]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    - waiting on <0x00007f651aa10338> (a java.lang.ref.Reference$Lock)
    at java.lang.Object.wait(Object.java:485)
    at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
    - locked <0x00007f651aa10338> (a java.lang.ref.Reference$Lock)

"main" prio=10 tid=0x0000000000622400 nid=0xbeb runnable [0x0000000000000000..0x00007fff69fcbba0]
   java.lang.Thread.State: RUNNABLE

"VM Thread" prio=10 tid=0x000000000068a000 nid=0xbf4 runnable 

"GC task thread#0 (ParallelGC)" prio=10 tid=0x000000000062cc00 nid=0xbec runnable 

"GC task thread#1 (ParallelGC)" prio=10 tid=0x000000000062e000 nid=0xbed runnable 

"GC task thread#2 (ParallelGC)" prio=10 tid=0x000000000062f400 nid=0xbee runnable 

"GC task thread#3 (ParallelGC)" prio=10 tid=0x0000000000630400 nid=0xbef runnable 

"GC task thread#4 (ParallelGC)" prio=10 tid=0x0000000000631800 nid=0xbf0 runnable 

"GC task thread#5 (ParallelGC)" prio=10 tid=0x0000000000632c00 nid=0xbf1 runnable 

"GC task thread#6 (ParallelGC)" prio=10 tid=0x0000000000634000 nid=0xbf2 runnable 

"GC task thread#7 (ParallelGC)" prio=10 tid=0x0000000000635400 nid=0xbf3 runnable 

"VM Periodic Task Thread" prio=10 tid=0x00007f6510006800 nid=0xbfb waiting on condition 

JNI global references: 1201

I know this is not a thread deadlock prob since one thread is actually runnning with all the ressource every other thread want.

Anyone got an idea of what can cause this prob ?

Answer 1

All your Threads are logging things. They all need to write on the disk from time to time. Everytime one of your 240 threads hits a logging line there will be disk access issues.

It baffles me that the Thread having the lock is in the RUNNABLE state.

I think it might be waiting for some external ressource to be released (like disk access for example)

Are you running low on disk space? Have you recently changed something in your storage system?