G1 GC Tuning parameters

[Narasimha C Achi]

Hi Team,

Please find attached logs. java web services are deployed in these servers.
Attachment 1: shows to-space exhausted and allocation failure
Attachment2: Log GC Pauses.

Please find below G1 GC setting ini all our 4 managed servers.

-XX:GCLogFileSize=10485760 -XX:InitialHeapSize=6442450944 -XX:MaxGCPauseMillis=50 -XX:MaxHeapSize=6442450944 -XX:NumberOfGCLogFiles=10 -XX:+PrintGC -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+ReduceSignalUsage -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseG1GC -XX:+UseGCLogFileRotation -XX:concGCThread=4 -XX:+ExplicitGC

Our observation is that heap utilization is more and free Heap Percentage comes to 8-9% and suddenly goes to 34%. Does this create any issues like outofmemory error and server crash?
How to fine tune these parameters and what other parameters to change for proper GC process with less stop world times.

Each server serves almost 50000 requests every day. Few times we observed to-space exhausted and Allocation Failure in GC logs.

Please provide us details about any other parameters to tune to avoid GC Issues.

Thanks and Regards
Narasimha Chary Achi




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