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From Paul.Lewandow...@kohls.com
Subject Re: Garbage collection
Date Mon, 04 Dec 2006 14:41:32 GMT
We ran into similar issues when first starting to use JCS.  The underlying
issue for us was that the remote cache uses RMI calls.  When RMI is in use,
the JVM may automatically trigger full GC's every 60 seconds as the
default; at least under our JDK 1.3.1...not sure about JDK 1.5 but I
believe they may have changed this to the values I will list below in the
JVM parameters that we added...you can tell by examining the GC consecutive
cycles...if they are exactly 60 seconds apart, every 60 seconds, then if
you add the parameters below you may see an improvement:

-Dsun.rmi.dgc.client.gcInterval=3600000
-Dsun.rmi.dgc.server.gcInterval=3600000
-Dsun.rmi.transport.tcp.connectionPool=true

Hope this helps.

Paul




                                                                           
             "Al Forbes"                                                   
             <forbes.al@google                                             
             mail.com>                                                  To 
                                       jcs-users@jakarta.apache.org        
             12/03/2006 04:30                                           cc 
             PM                                                            
                                                                   Subject 
                                       Garbage collection                  
             Please respond to                                             
             "JCS Users List"                                              
             <jcs-users@jakart                                             
               a.apache.org>                                               
                                                                           
                                                                           




Hi,

I have a remote cache setup with a memory+disk cache, pure memory, and
a mysql cache (0 memory). This uses the latest JCS jcs-1.2.7.9.2.jar
in JDK1.5.


After starting the times for a "Full" grabage collection get longer
and longer. Eventually after about 10-12 days I need to restart the
remote cache. Also when the full garbage collection runs it uses more
and more CPU. Memory usage remains fairly constant (round 600M), and
the incremental collections are fairly small 0.02 secs. I wonder if
anyone these has seen the same thing, or has any better suggestions
for the garbage collection.

Full collection:
559228.304: [Full GC 559228.304: [CMS: 214224K->171110K(393216K),
1.2718260 secs] 328232K->171110K(524224K), [CMS Perm :
8565K->8540K(16384K)] icms_dc=0 , 1.2720400 secs]

I currently have the garbage collection configured to:

   MEMUSE="-Xms512m -Xmx1024m"
   MEMUSE=" $MEMUSE -XX:+UseConcMarkSweepGC \
     -XX:NewSize=128m -XX:MaxNewSize=128m \
     -XX:+CMSIncrementalMode \
     -XX:+CMSIncrementalPacing \
     -XX:CMSIncrementalDutyCycleMin=0 \
     -XX:CMSIncrementalDutyCycle=10 \
     -XX:+PrintGCDetails \
     -XX:+PrintGCTimeStamps \
     -Xloggc:../logs/gc.log \
     -XX:-TraceClassUnloading"

Regards
Al

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