how to see Garbage Collector and change options

[Former Member]

Hi..

Can someone tell me how I can know when all the garbage collector works in the JAVA system? I want to know whether a minimal GC is happening or a heavy GC is happening which could be creating any bottle necks to the system. I also want to know where I can see how much time Garbage collector took on the system.

Please advise.

Thanks, Jim.

System - Web AS ABAP+JAVA (BI 7)

Db - SQL Server

OS - MS Windows

[Former Member · Accepted solution]

Hi,

GC is not SAP topic but Java VM topic. You should find and read your JDK vendor documents for GC specific. Pelase try the online documentation of SUN, IBM, HP.

Kind regards,

Tsvetomir

[former_member265210]

1. JVM has GC parameters like -XX:-PrintGCDetails, -XX:-PrintGCTimeStamps ,-Xloggc:GC.log ,-XX:UseParallelGC,-XX:DisableExplicitGC, -XX:+UseParNewGC

try to get more + ive & - ive info of above parameters.

2. GC path <SID>JC<>j2eeclusterserver0gc.log & also check for each server node in "Work" folder

3. when all the garbage collector works in the JAVA system?

Ans: in simple terms...when there is not enough memory to store the info then JVM trigger the GC to

clean up the mem.

4. I want to know whether a minimal GC is happening or a heavy GC is happening which could be creating any bottle necks to the system..

Ans: in GC.log file look for text "FULL GC". if exist then full GC is happening.

5. I also want to know where I can see how much time Garbage collector took on the system.

Ans: https://www.sdn.sap.com/irj/sdn/wiki?path=/display/java/javaMemoryAnalysis

Regards

Shridhar Gowda

[former_member200234]

Hi Jim ,

The Wily Introscope is a powerfull tool to analyze your J2EE engine.

Please take a look at

Note 797147 - Wily Introscope Installation for SAP Customers

Also in the /usr/sap/<SID>/JCXX/work directory you can find the

dev_server0 and std_server0.out files which provide you with info about the GC proces

Cheers,

E

[Former Member]

Hi,

Go through the contents under "Garbage Collector options" in the SAP Note 723909 - Java VM settings for J2EE 6.40/7.0

Hope this gives a start for your analysis !

Regards

Srinivasan T