Bug in G1GC it performs Full GC when code cache is full resulting in overkill

[Martin Makundi]

Hi!

For long time, we have had about 10gb more memory than what we need,
but about 1-3 times per day in production, the G1GC performs Full GC
without any apparent reason.

Recently we installed Appdynamics profiler which shows also Code Cache
memory levels. To our surprise we noticed, that every time the code
cache becomes almost full, G1GC performs a Full GC, which we ofcourse
consider an overkill because the Full GC takes nearly 60 seconds every
time with our memory size!

Is this a bug in G1GC or is there a configuration option to disable
such behavior?



See profiler snapshots at:

http://eisler.vps.kotisivut.com/logs/g1gc-code-cache-full-gc-bug-illustration.png

The issue is not an isolated occurrence, it occurs daily.

Similar posts can be found on the web where G1GC performs Full GC with
no apparent reason:

http://grokbase.com/t/openjdk/hotspot-gc-use/1192sy84j5/g1c-strange-full-gc-behavior
http://grokbase.com/p/openjdk/hotspot-gc-use/123ydf9c92/puzzling-why-is-a-full-gc-triggered-here


**
Martin