I gave 3GB total heap space of activemq, the XX:NewRatio=2. So new generation 1GB and old generation 2GB. And I also config memoryUsage limit="1 gb"
ACTIVEMQ_OPTS_MEMORY="-Xms1G -Xmx3G -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:CMSInitiatingOccupancyFraction=70 -XX:NewRatio=2" There are only two queues. <policyEntry queue=">" optimizedDispatch="true" producerFlowControl="false" cursorMemoryHighWaterMark="70" memoryLimit="100 mb" /> <systemUsage> <systemUsage> <memoryUsage> <memoryUsage limit="1 gb" /> </memoryUsage> <storeUsage> <storeUsage limit="50 gb"/> </storeUsage> <tempUsage> <tempUsage limit="50 gb"/> </tempUsage> </systemUsage> </systemUsage> $ jstat -gcutil 10345 1000 S0 S1 E O P YGC YGCT FGC FGCT GCT 99.72 0.00 100.00 100.00 59.94 293 14.149 69 115.657 129.806 99.72 0.00 100.00 100.00 59.94 293 14.149 69 115.657 129.806 0.00 0.00 58.20 100.00 59.94 293 14.149 70 129.375 143.524 0.00 0.00 62.86 100.00 59.95 293 14.149 70 130.325 144.474 0.00 0.00 72.10 100.00 59.98 293 14.149 70 130.325 144.474 0.00 0.00 85.59 100.00 59.98 293 14.149 70 130.325 144.474 0.00 0.00 99.82 100.00 59.98 293 14.149 70 130.325 144.474 46.40 0.00 100.00 100.00 59.99 293 14.149 70 130.325 144.474 99.96 0.00 100.00 100.00 60.00 293 14.149 71 130.325 144.474 99.96 0.00 100.00 100.00 60.00 293 14.149 71 130.325 144.474 99.96 0.00 100.00 100.00 60.00 293 14.149 71 130.325 144.474 $ jmap -heap 10345 Attaching to process ID 10345, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.45-b08 using parallel threads in the new generation. using thread-local object allocation. Concurrent Mark-Sweep GC Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 3221225472 (3072.0MB) NewSize = 1310720 (1.25MB) MaxNewSize = 17592186044415 MB OldSize = 5439488 (5.1875MB) NewRatio = 2 SurvivorRatio = 8 PermSize = 21757952 (20.75MB) MaxPermSize = 85983232 (82.0MB) G1HeapRegionSize = 0 (0.0MB) Heap Usage: New Generation (Eden + 1 Survivor Space): capacity = 966393856 (921.625MB) used = 966388976 (921.6203460693359MB) free = 4880 (0.0046539306640625MB) 99.99949502990218% used Eden Space: capacity = 859045888 (819.25MB) used = 859045888 (819.25MB) free = 0 (0.0MB) 100.0% used >From Space: capacity = 107347968 (102.375MB) used = 107343088 (102.37034606933594MB) free = 4880 (0.0046539306640625MB) 99.99545403598138% used To Space: capacity = 107347968 (102.375MB) used = 0 (0.0MB) free = 107347968 (102.375MB) 0.0% used concurrent mark-sweep generation: capacity = 2147483648 (2048.0MB) used = 2147483608 (2047.9999618530273MB) free = 40 (3.814697265625E-5MB) 99.99999813735485% used Perm Generation: capacity = 52916224 (50.46484375MB) used = 31660712 (30.194007873535156MB) free = 21255512 (20.270835876464844MB) 59.83176728558712% used