IBM BS029ML Self Help Guide - Page 160
Additional SUN JVM attributes, Servers, Application Servers, WebSphere_Portal, Server Infrastructure
View all IBM BS029ML manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 160 highlights
As the Portal Server places a greater demand on JVM memory, you should increase the Java minimum and maximum heap sizes accordingly. To view or modify the SUN JVM settings from the WebSphere Application Server Administrative Console, select Servers → Application Servers → WebSphere_Portal → Server Infrastructure → Java and Process Management → Process Definition → Java Virtual Machine. Table 5-3 shows the default and recommended values. Table 5-3 SUN JVM settings Parameter JVM initial heap size JVM maximum heap size Default value n/a n/a Recommended value 1536 2048 Additional SUN JVM attributes For the SUN JVM, we strongly recommend that you set a number of additional JVM attributes to fine-tune the behavior of the generational heap. Increase the size of the Young generation heap (NewSize and MaxNewSize), as objects in this heap should not live through more then one garbage collection (GC) cycle. Up to 50% to 60% of the total heap size can be set for the Young generation. Also, consider slightly increasing SurvivorRatio. Additionally, ensure that the Permanent generation (PermSize and MaxPermSize) is adequately sized to hold all class loaded data. This includes classes loaded at Portal Server runtime startup and dynamically compiled JSPs. If the Permanent generation becomes full, a Full GC will result. Note: The Permanent generation is not allocated from the heap defined by either the (-Xms) or (-Xmx) settings. To view or modify the SUN JVM settings from the WebSphere Application Server Administrative Console, select Servers → Application Servers → WebSphere_Portal → Server Infrastructure → Java and Process Management → Process Definition → Java Virtual Machine. Table 5-4 shows the default and recommended values. Table 5-4 Additional SUN JVM settings Parameter HotSpot Server option Default size of New Generation (in bytes) Default value n/a n/a Maximum size of New Generation (in bytes). n/a Default size of Permanent Generation n/a Maximum Permanent Generation Size n/a Ratio of Eden / Survivor Space Size n/a GC Concurrent Collector n/a GC Parallel Collector n/a Recommended value -server -XX:NewSize=(50% to 60% of heap) -XX:MaxNewSize=(50% to 60% of heap) -XX:PermSize=512m -XX:MaxPermSize=768 m -XX:SurvivorRatio=16 -XX: +UseConcMarkSweep GC -XX:+UseParNewGC 146 IBM WebSphere Portal V6 Self Help Guide