Hi Peter, I am not sure that it was due to AggressiveHeap. I did try to set the -XX:NewSize=400M -XX:MaxNewSize=400M, Full GC is happening every minute So now options are | JAVA_OPTS="-server -Xms1500m -Xmx1500m -Xss128k -XX:NewSize=400M -XX:MaxNewSize=400M -verbose:gc -Xloggc:/opt/jboss-4.2.0.GA/logs/GC.log -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -XX:+UseLargePages -XX:PermSize=512m -XX:MaxPermSize=512m -XX:ThreadStackSize=512 -XX:+UseParallelGC -XX:CompileThreshold=100 -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:MaxTenuringThreshold=31" | see the excerpts from GC.log | 4.083: [GC [PSYoungGen: 92161K->4011K(358400K)] 92161K->4011K(1484800K), 0.0105160 secs] | 4.093: [Full GC [PSYoungGen: 4011K->0K(358400K)] [PSOldGen: 0K->3912K(1126400K)] 4011K->3912K(1484800K) [PSPermGen: 10442K->10442K(524288K)], 0.0647090 secs] | 14.868: [GC [PSYoungGen: 307200K->16084K(358400K)] 311112K->19996K(1484800K), 0.0257470 secs] | 24.043: [GC [PSYoungGen: 323284K->35371K(358400K)] 327196K->39283K(1484800K), 0.0585670 secs] | 29.813: [GC [PSYoungGen: 342571K->46513K(358400K)] 346483K->50425K(1484800K), 0.0626800 secs] | 64.215: [GC [PSYoungGen: 267394K->51194K(358400K)] 271306K->68206K(1484800K), 0.0918350 secs] | 64.307: [Full GC [PSYoungGen: 51194K->0K(358400K)] [PSOldGen: 17011K->67462K(1126400K)] 68206K->67462K(1484800K) [PSPermGen: 56403K->56403K(524288K)], 0.5361080 secs] | 124.906: [GC [PSYoungGen: 151055K->4753K(358400K)] 218518K->72216K(1484800K), 0.0107620 secs] | 124.916: [Full GC [PSYoungGen: 4753K->0K(358400K)] [PSOldGen: 67462K->72103K(1126400K)] 72216K->72103K(1484800K) [PSPermGen: 62877K->62877K(524288K)], 0.5240890 secs] | 185.465: [GC [PSYoungGen: 18961K->306K(358400K)] 91065K->72410K(1484800K), 0.0044300 secs] | 185.470: [Full GC [PSYoungGen: 306K->0K(358400K)] [PSOldGen: 72103K->70911K(1126400K)] 72410K->70911K(1484800K) [PSPermGen: 62898K->62728K(524288K)], 0.5783190 secs] | 246.080: [GC [PSYoungGen: 17583K->321K(358400K)] 88495K->71233K(1484800K), 0.0043550 secs] | 246.084: [Full GC [PSYoungGen: 321K->0K(358400K)] [PSOldGen: 70911K->71137K(1126400K)] 71233K->71137K(1484800K) [PSPermGen: 62754K->62754K(524288K)], 0.4824640 secs] | | View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4233990#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...