Interpreting error message

[Vibha Harikar]

Hi,
   We have a Java (1.5) app (running on Tomcat 5.5.X)
that is experiencing some production issues. At times
one one of the Tomcat instances will lockup and cause
the entire application to be unresponsive. In the
thread dumps of one of the JVM's we see a large number
of messages like (apart from many others) :

"JMX server connection timeout 38" daemon prio=1
tid=0x08aa9b20 nid=0x596c in Object.wait()
[0x670fc000..0x670fcda0]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x72af9090> (a [I)
        at
com.sun.jmx.remote.internal.ServerCommunicatorAdmin$Timeout.run(ServerCommunicatorAdmin.java:150)
        - locked <0x72af9090> (a [I)
        at java.lang.Thread.run(Thread.java:595)

There's at least 1300 threads in this state. What does
this signify ? Is this significant or just a symptom
of some other problem we could be facing ..?

Any pointers would be appreciated.

Thanks,
Vibha.


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[eamonn.mcmanus]

Vibha,

The stack trace you show is normal when a remote JMX client connects to a
server.  But if you are seeing 1300 threads with the same stack trace then
that normally means you have 1300 remote JMX connections.  You might want to
check this with system tools (such as netstat on Unix-like systems).

Another thing you can try is to turn on JMX logging.  I usually do this by
running my application with
-Djava.util.logging.config.file=$HOME/java/jmx.logging.properties, where
that file contains the following:

handlers= java.util.logging.ConsoleHandler
javax.management.level=FINEST

java.util.logging.ConsoleHandler.level = FINEST
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter

Setting the property on the command line and logging to System.err, as here,
might not be appropriate in your environment, but you should be able to
figure out alternatives if necessary.

Hope this helps,
Éamonn McManus  --  JMX Spec Lead  --  http://weblogs.java.net/blog/emcmanus

On Sun, 15 Jul 2007 16:19:55 -0700, Vibha Harikar <vharikar@...> wrote:

>Hi,
>   We have a Java (1.5) app (running on Tomcat 5.5.X)
>that is experiencing some production issues. At times
>one one of the Tomcat instances will lockup and cause
>the entire application to be unresponsive. In the
>thread dumps of one of the JVM's we see a large number
>of messages like (apart from many others) :
>
>"JMX server connection timeout 38" daemon prio=1
>tid=0x08aa9b20 nid=0x596c in Object.wait()
>[0x670fc000..0x670fcda0]
>        at java.lang.Object.wait(Native Method)
>        - waiting on <0x72af9090> (a [I)
>        at
>com.sun.jmx.remote.internal.ServerCommunicatorAdmin$Timeout.run(ServerCommunicatorAdmin.java:150)
>        - locked <0x72af9090> (a [I)
>        at java.lang.Thread.run(Thread.java:595)
>
>There's at least 1300 threads in this state. What does
>this signify ? Is this significant or just a symptom
>of some other problem we could be facing ..?
>
>Any pointers would be appreciated.
>
>Thanks,
>Vibha.

===========================================================================
For information on the Java Management extensions (JMX), please visit
our home page at http://java.sun.com/products/JavaManagement/
The JMX-FORUM archives are accessible at http://archives.java.sun.com
To unsubscribe, send email to listserv@... and include in the body
of the message "signoff JMX-FORUM".  For general help, send email to
listserv@... and include in the body of the message "help".