Using G1GC of JDK 8 on Cloudera

[#1]

Hi,

We have CDH 5.15 on our production cluster with JDK 8,

What is your recommendation about moving to G1GC or stay with the CMS,

didn't find any clear instruction about it.

Does it depend on the CDH version? or on the components I'm using?

Thanks

[#2 · Accepted solution]

The CMS + Parallel New collector does a decent job for mid-to-high heaps. It continues to remain our default, although things may change with the introduction of newer JDK (LTS) support in future.

G1 is a great new collector that's been improving since its inception, and if you are going to use it, I advise using the latest JDK8 version available.

Most of the cases where we've had to recommend G1 GC over the stock defaults typically arise out of specific workload and heap pattern analysis.

Are you facing long pauses with CMS + ParNew collectors? What are the pauses caused by, according to your GC logging (allocation failure? too low new-size? etc.)?

Its worth measuring what's impacting the current heap collector configuration, as a simple switch will only bring in limited improvements that may not truly/automatically solve your existing problems.

[#3]

We don't have any critical issues.
We just saw in other systems (Cassandra, Kafka etc) that G1GC brought better performance and fewer problems so we thought to use it also for CDH, but I see from your answer it is not a big change.
Thanks!