Identify Java code consuming high CPU in Linux-linking JVM thread and Linux PID

Identify Java code consuming high CPU in Linux--linking JVM thread and Linux PID

The original article is in : http://blogs.manageengine.com/appmanager/2011/02/09/identify-java-code-consuming-high-cpu-in-linux-linking-jvm-thread-and-linux-pid/

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We can easily identify a problematic java code which leads to high CPU utilization in Linux. Let me explain the steps with the following example,

Step 2 :

The top command displays the process list like the above image. Press ‘Shift + h‘ and wait few secs. You can see ‘Show threads on‘ message in the top console. Now, you can see thread level details like CPU/Memory utilization. You can see a ‘java’ command thread with PID 7087 utilized 94% of CPU.



Step 3:

The identified problematic thread PID ( 7087 ) is in decimal format. Convert it into hexadecimal format. The respective hexadecimal for 7087 is 1BAF. And convert it into lowercase (1baf ).

Step 4:

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Take thread dump and search the converted hexadecimal PID ( 1baf ) in the thread dump. You can find the hex PID as ‘nid‘ (with ’0x’) of the thread trace. From the trace, you can find ‘MyThread-1005‘ is the problematic thread in the test program. And using the thread trace you can identify the problematic code and fix the problem.
[rameshj@rameshj thread]$ java test/ThreadDumpTest^\Full thread dump Java HotSpot(TM) Client VM (1.5.0_06-b05 mixed mode):“DestroyJavaVM” prio=1 tid=0x083d2d78 nid=0x1ba2 waiting on condition [0x00000000..0xbff4bf60]“MyThread-1009″ prio=1 tid=0x08510a88 nid=0x1bb3 waiting on condition [0xa9cca000..0xa9ccb020]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)??????????&nbs
p;????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????????????????? “MyThread-1008″ prio=1 tid=0×08510318 nid=0x1bb2 waiting on condition [0xa9d4b000..0xa9d4bea0]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)???????????????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????????????????? “MyThread-1007″ prio=1 tid=0x0850f298 nid=0x1bb1 waiting on condition [0xa9dcc000..0xa9dccf20]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)???????????????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????????????????? “MyThread-1006″ prio=1 tid=0x0850d818 nid=0x1bb0 waiting on condition [0xa9e4d000..0xa9e4dda0]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)???????????????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)?????????????????????????????????????????????
1. “MyThread-1005” prio=1 tid=0x0850c9f8 nid=0x1baf runnable [0xa9ece000..0xa9ecee20]
2. ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:43)????????????????????
3. ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????? “MyThread-1004″ prio=1 tid=0x0850b8e8 nid=0x1bae waiting on condition [0xa9f4f000..0xa9f500a0]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)???????????????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????????????????? “MyThread-1003″ prio=1 tid=0x0850aac8 nid=0x1bad waiting on condition [0xa9fd0000..0xa9fd1120]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)???????????????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????????????????? “MyThread-1002″ prio=1 tid=0x085099b8 nid=0x1bac waiting on condition [0xaa051000..0xaa051fa0]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)???????????????????????????????? ??????? at java.lang.Thread.run(Thread.java:595)????????????????????????????????????????????? “MyThread-1001″ prio=1 tid=0x08508a28 nid=0x1bab waiting
   on condition [0xaa0d2000..0xaa0d3020]??????? at java.lang.Thread.sleep(Native Method)????????????????????????????????????????????? ??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)??????? at java.lang.Thread.run(Thread.java:595)“MyThread-1000″ prio=1 tid=0×08508520 nid=0x1baa waiting on condition [0xaa153000..0xaa153ea0]??????? at java.lang.Thread.sleep(Native Method)??????? at test.ThreadDumpTest$TR.run(ThreadDumpTest.java:45)??????? at java.lang.Thread.run(Thread.java:595)“Low Memory Detector” daemon prio=1 tid=0x0843cf58 nid=0x1ba8 runnable [0x00000000..0x00000000]“CompilerThread0″ daemon prio=1 tid=0x0843b930 nid=0x1ba7 waiting on condition [0x00000000..0xaa3eb808]“Signal Dispatcher” daemon prio=1 tid=0x0843a9d0 nid=0x1ba6 waiting on condition [0x00000000..0x00000000]“Finalizer” daemon prio=1 tid=0×08430740 nid=0x1ba5 in Object.wait() [0xaa52c000..0xaa52d120]??????? at java.lang.Object.wait(Native Method)??????? – waiting on <0xaa6b0848> (a java.lang.ref.ReferenceQueue$Lock)??????? at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116)??????? – locked <0xaa6b0848> (a java.lang.ref.ReferenceQueue$Lock)??????? at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132)??????? at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)“Reference Handler” daemon prio=1 tid=0x0842e898 nid=0x1ba4 in Object.wait() [0xaa5ad000..0xaa5adfa0]??????? at java.lang.Object.wait(Native Method)??????? – waiting on <0xaa6b0758> (a java.lang.ref.Reference$Lock)??????? at java.lang.Object.wait(Object.java:474)??????? at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)??????? – locked <0xaa6b0758> (a java.lang.ref.Reference$Lock)“VM Thread” prio=1 tid=0x0842bb68 nid=0x1ba3 runnable“VM Periodic Task Thread” prio=1 tid=0x0843e538 nid=0x1ba9 waiting on condition

Update : FYI : You can automatically take a thread dump of a Java application when a high CPU threshold is violated by using Applications Manager. ?Learn more?or watch a related video or download Applications Manager now.