Need help on long minor GC pause

[Avinash Mishra]

Hi folks,

We are facing a strange issue where the minor GC gets stuck for several seconds:


734827.324: [GC 639235K->587610K(1042048K), 2.4140118
secs] 
734846.488: [GC 640090K->589859K(1042048K), 22.1046232 secs] 
734949.577: [GC 642339K->590078K(1042048K), 12.2527731 secs] 
735045.592: [GC 642558K->591084K(1042048K), 0.1158979
secs]
 Our Java configuration is something like this:

java -Xms1024m -Xmx1024m -XX:+UseConcMarkSweepGC -cp %MY_CLASSPATH% com.myclass


We are using Java 1.6u24 and the application is running on a Windows 2003 server.

The issue is specific to a couple of servers at a customer site and nowhere else. The servers here run fine for up to some 45 days when the issue shows up.

From the logs(above) it seems that there is plenty of old space available on heap so we have ruled out concurrent failures. We are looking into fragmentation as the potential root cause. We have enabled these traces to confirm if we have a fragmentation issue


-XX:+PrintGCDetails
-XX:+PrintPromotionFailure
-XX:PrintFLSStatistics=1

From these logs we are monitoring "Max chunk available" and look for a decrease in trend to determine if the servers are heading towards a fragmentation problem. Please let me know if anything else is required to confirm on fragmentation issue and if there is a a way to confirm it sooner instead of waiting for couple of months.


Please let me know if you have any other pointers on potential root cause.

Thanks,
Avinash
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