We are currently on elasticsearch version 7.0.1 and about to upgrade to 7.8. In our elastic search logs, we observe a warning "OpenJDK 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release."
On analysis, we found that CMS gc is deprecated from java 9 onwards and be completely removed from java 14. Currently, we are on java 11.
We found that this warning can be avoided by replacing CMSGC with G1GC (garbage collectors).
Following is the code snippet for configuring GC:
## GC configuration 8-13:-XX:+UseConcMarkSweepGC 8-13:-XX:CMSInitiatingOccupancyFraction=75 8-13:-XX:+UseCMSInitiatingOccupancyOnly ## G1GC Configuration # NOTE: G1 GC is only supported on JDK version 10 or later # to use G1GC, uncomment the next two lines and update the version on the # following three lines to your version of the JDK # 10-13:-XX:-UseConcMarkSweepGC # 10-13:-XX:-UseCMSInitiatingOccupancyOnly 14-:-XX:+UseG1GC 14-:-XX:G1ReservePercent=25 14-:-XX:InitiatingHeapOccupancyPercent=30
Please suggest what impact can be seen after changing this JVM option. Is there any performance impact or what possibly could get affected if we switch to G1GC from CMSGC?
Thanks in advance