Java Virtual Machine counters

The Java Virtual Machine (JVM) counters are used to monitor JVM performance. Except for the counters used for total, used, and free heap size, you can find the counters by using the Java virtual machine Profiler Interface (JVMPI). To use JVMPI, you must turn on the monitoring by setting the -XrunpmiJvmpiProfiler command line. See Enabling Java Virtual Machine Profiler Interface data reporting.

Note: With the instrumentation level set to anything other than MAX, the values may be less accurate for TimeStatistics and CountStatistics (and in the case of CountStatistics, such as numConnectionHandles, can even be negative). This is due to counters not being synchronized. Synchronizing counters is very expensive in terms of resources, so it is only done when the instrumentation level is set to MAX.

Counter definitions
Name Key Description Version Granularity Type Level
Free memory (KB) jvmRuntimeModule.freeMemory The free memory in the JVM run time 3.5.5 and later Per Java Virtual Machine (JVM) CountStatistic Low
Used memory (KB) jvmRuntimeModule.usedMemory The used memory in the JVM run time 3.5.5 and later Per JVM CountStatistic Low
Total memory (KB) jvmRuntimeModule.totalMemory The total memory in the JVM run time 3.5.5 and later Per JVM BoundedRangeStatistic. The upperBound and lowerBound are not implemented for the Total memory counter. High
JVM up time (seconds) jvmRuntimeModule.upTime The amount of time that the JVM is running 5.0 Per JVM CountStatistic Low
Num GC calls jvmRuntimeModule.numGcCalls The number of garbage collection calls. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max
Avg time between GC calls (ms) jvmRuntimeModule.avgTimeBetweenGcCalls The average garbage collection value in seconds between two garbage collections. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM TimeStatistic Max
Avg GC duration (ms) jvmRuntimeModule.avgGcDuration The average duration of a garbage collection. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM TimeStatistic Max
Num waits for lock jvmRuntimeModule.numWaitsForLock The number of times that a thread waits for a lock. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max
Avg time wait for lock jvmRuntimeModule.avgTimeWaitForLock The average time that a thread waits for a lock. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM TimeStatistic Max
Num objects allocated jvmRuntimeModule.numObjectsAllocated The number of objects that are allocated in the heap. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max
Num objects moved jvmRuntimeModule.numObjectsMoved The number of objects in the heap. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max
Num objects freed jvmRuntimeModule.numObjectsFreed The number of objects freed in the heap. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max
Num started threads jvmRuntimeModule.numThreadsStarted The number of threads started. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max
Num dead threads jvmRuntimeModule.numThreadsDead The number of failed threads. This counter is not available unless the -XrunpmiJvmpiProfiler option is set when starting the JVM. 4.0 and later Per JVM CountStatistic Max



Related tasks
Enabling Java Virtual Machine Profiler Interface data reporting
Related reference
Performance data organization



Searchable topic ID:   rprf_datacounter4
Last updated: Jun 21, 2007 8:07:48 PM CDT    WebSphere Business Integration Server Foundation, Version 5.0.2
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