G1 GC for 100GB+ heaps

Kees Jan Koster kjkoster at java-monitor.com
Wed Jul 22 13:51:59 UTC 2015

Dear All,

Marcus Lagergren suggested I post these questions on this list. We are considering switching to using the G1 GC for a decently sized HBase cluster, and ran into some questions. Hope you can help me our, or point me to the place where I should ask.

First -> sizing: Our machines have 128GB of RAM. We run on the bare metal. Is there a practical limit to the heap size we should allocate to the JVM when using the G1 GC? What kind of region sizing should we use, or should we just let G1 do what it does?

Second -> failure modes. Does G1 have any failure or fall-back modes that it will use for edge cases? How do we monitor for those?

Finally: Are there any gotcha’s to keep in mind, or any tunables that we have to invest time into when we want to run smoothly with 100GB+ heap sizes?

Kees Jan

kjkoster at kjkoster.org

Change is good. Granted, it is good in retrospect, but change is good.

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