A significant amount of JVM stopped time is not GC related

Issue

• GC analysis shows a significant amount of JVM stopped time is not GC related. For example, garbagecat summary output shows a high total stopped time and a relatively low GC total pause time or a low GC/stopped ratio, as in the example below:

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SUMMARY:
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# GC Events: 1032
Event Types: PARALLEL_SCAVENGE, PARALLEL_COMPACTING_OLD
# Parallel Events: 1032
# Inverted Parallelism: 0
NewRatio: 2
Max Heap Occupancy: 5235541K
Max Heap Space: 8339456K
Max Perm/Metaspace Occupancy: 182728K
Max Perm/Metaspace Space: 1251328K
GC Throughput: 99%
GC Max Pause: 2.934 secs
GC Total Pause: 71.572 secs
Stopped Time Throughput: 70%
Stopped Time Max Pause: 20.711 secs
Stopped Time Total: 2238.507 secs
GC/Stopped Ratio: 3%
First Timestamp: 0.143 secs
Last Timestamp: 7541.137 secs
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• Application is evidencing unexplained latency and freezes when heap or permgen / metaspace are not near configured limits
• Process monitoring tools are showing high CPU usage by the application - particularly by the VM Thread with relatively low GC overhead