jlaunch up 99% of CPU

[Former Member]

Hi everybody!

CRM 7.0 (abap+java) - DEV-System shows nearly 100% of CPU from jlaunch-process while no user activity is on the system.

AIX 5.3

java full version "J2RE 1.4.2 IBM AIX 5L for PowerPC (64 bit JVM) ...SR7 ...

The only hint a have is the continuing GC-entry in the std_server0.out:

<sys id="2" timestamp="Thu Mar 10 15:47:15 2011" intervalms="6256.576">

<time exclusiveaccessms="0.209" />

<nursery freebytes="113830616" totalbytes="310275072" percent="36" />

<tenured freebytes="1660896896" totalbytes="1728053248" percent="96" >

<soa freebytes="1574494848" totalbytes="1641651200" percent="95" />

<loa freebytes="86402048" totalbytes="86402048" percent="100" />

</tenured>

<gc type="global" id="2" totalid="15" intervalms="6256.830">

<compaction movecount="2078433" movebytes="164856336" reason="compact on aggressive collection" />

<classloadersunloaded count="4" timetakenms="4.388" />

<refs_cleared soft="39" threshold="32" weak="24" phantom="0" />

<finalization objectsqueued="313" />

<timesms mark="177.623" sweep="14.288" compact="449.535" total="646.103" />

<nursery freebytes="210930480" totalbytes="310275072" percent="67" />

std_server0.out (2%)

<loa freebytes="86402048" totalbytes="86402048" percent="100" />

</tenured>

<time totalms="1346.501" />

</sys>

Thanks for any help!!

Regards

Uwe

[AtulKumarJain · Accepted solution]

Hi Uwe,

Please have a look into below link,it seems same as your issue.

Best regards,

Atul

[Former Member · Accepted solution]

Thanks for the Link. I have already checked all the nodes from this Thread.

The java parameters have been checked. They seem to be fine. I hadn't expect any wrong parameter settings, as the system has benn running for a long time without these problems.

One interessting / confusing situation on the process-analyzing regarding note 743191:

Whenever I start to 'debugg' the jlaunch-process (that causes the cpu usage), the CPU usage immediatly goes down to a normal value. As sonns as I detach the process and release him from debugging, the problem starts again and usage goes up to nearly 100%. So I am not able to do a qualified analysis on the problem regarding note 743191.

Any ideas?

Regards,

Uwe

[Former Member · Accepted solution]

Well the debugger seems to slow down the process, but you should still be able to see what is going on at the moment.

Besides that, you should take a few thread dumps and compare them to get information on running threads, and if there are locking issues. If you have solman diagnostics configured you can do this with the root cause analysis feature. If you don't, then use a tool like the thread dump viewer [https://service.sap.com/sap/support/notes/1020246]

When you restart the system, does the CPU immediately go to 100% after the server process is reaches the running state?

Cheers Michael

[Former Member · Accepted solution]

Hi Michael!

Yes, when I restart the system, the CPU does immediately go to 100% after the server process is reaches the running state.

Uwe

[Former Member · Accepted solution]

1. Just to be on safe side, reset the logging activity to default in VA--> LOG CONF --> RESET TO DEFAUL under root and locations, this would ensure additional logs are not written

2. get a thread dump, pid --> command kill -3 pid --> dev-server0 and use the tdviewer to see if there any locks or hangs in the threads

3. set the -Xms and -Xmx to 2048M and check all the config tool --> server node parameters and paste them here when your are replying to this thread.

4. If this is bcz of recent deployment then we need to check the thread dump as well.

Let me know.

Regards

SM.

[Former Member · Accepted solution]

Hi Guys,

the problem has been resolved:

Cause was the Garbage Collector, that ran nonstop.

SAP recommended to set the java parameter -Xdisableexplicitgc.

As soon as we did this, the cpu usage went down to a normal level.

The parameter is mentioned in certain sap notes (contianing java recommendations), but unfortunately I wasn't able to find any documentation for this parameter. So right now I have no clue on the effect regarding to my GC. I asked SAP for information. I will let you know if I get an anwser.

Of course, if anybody of you has got information, please let me know!

regards

Uwe

[Former Member · Accepted solution]

Well it is possible to start a garbage collection from a java application with the System.gc() call. In a j2ee environment this is not wanted, the server should take care of garbage collecting itself.

With -Xdisableexplicitgc these calls are ignored, as far as i know you should always specify it for SAP J2EE's. But i never heard of any problems so far.

There is a lot of information on this, have a look here:

[Garbage collection advanced diagnostics|http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/index.jsp?topic=/com.ibm.java.doc.diagnostics.60/html/gcpd_advanced.html]

[When is a System.gc() not a System.gc()? |https://www.ibm.com/developerworks/mydeveloperworks/blogs/troubleshootingjava/entry/when_is_a_system_gc_not_a_system_gc2?lang=en]

Cheers Michael

[Former Member · Accepted solution]

In my experience when ever we install J2EE or add server node, by default this parameter -XXdisableexplicitGC is present in the java arguments of the server node.

I dont know how you guys missed it, bcz as per note 723909 it must be in every server node.

Regards

SM.

[Former Member · Accepted solution]

Try changing the Jlaunch binaries either upgrade or degrade and also check Java binaries for any issues.

All the best.

[Former Member · Accepted solution]

Thanks SM!

This solved our problem. (-XXdisableexplicitGC)

Uwe