Hi,
On 24.02.20 22:03, Bernd Eckenfels wrote:
Hello Mohd,
Would be good if you can upload sample GC logs which show the issue. If
a mixed collection does not clean up your heap but a FullGC does you
might need to look into soft references or direct buffers.
If you have generally smallish heap one option would be to go to
ParallelOld GC, it is less sensitive to fragmentation.
Gruss
Bernd
--
http://bernd.eckenfels.net
------------------------------------------------------------------------
*Von:* hotspot-gc-use <hotspot-gc-use-boun...@openjdk.java.net> im
Auftrag von mohd shaban <mohdshaban000...@gmail.com>
*Gesendet:* Monday, February 24, 2020 8:45:35 PM
*An:* Leo Korinth <leo.kori...@oracle.com>;
hotspot-gc-use@openjdk.java.net <hotspot-gc-use@openjdk.java.net>
*Betreff:* Re: How to do force full garbage collection when heap usage
goes beyond a certain threshold
Hi Leo ,
Actually we set up alerts for heap utilisation and we are getting to
many alerts.
So we have done the analysis and found more heap utilisation and once GC
happened it backs to normal but suppose my alert scheduler runs at 8:00
and at the same heap usage reach to 90 then we get the alert, But when i
monitor the heap usage , after 8:02 GC happened and it back to normal
usage means 50%.
So that why we want if heap usage reaches to 80-85% we trigger the GC so
that we can't get the alerts.
Please suggest how can we achieve this?
by default, in jdk9+ targets 90% heap occupancy (100 -
G1ReservePercent) to be the threshold at which old generation should be
reclaimed. I.e. G1 will automatically start liveness analysis in the old
gen so that at (roughly) 90% of heap usage it will start cleaning out
old gen.
So unless you get full gcs (or evacuation failures, i.e. "to-space
exhausted") this behavior is normal with default options, and could
likely be fixed by increasing the G1ReservePercent value (default 10).
GC logs, options used and JDK version used would help a lot to further
diagnose the issue.
Thanks,
Thomas
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