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From Graham Sanderson <gra...@vast.com>
Subject Re: High CPU usage on some of nodes
Date Thu, 10 Sep 2015 19:00:28 GMT
Haven’t been following this thread, but we run beefy machines with 8gig new gen, 12 gig old
gen (down from 16g since moving memtables off heap, we can probably go lower)…

Apart from making sure you have all the latest -XX: flags from cassandra-env.sh (and MALLOC_ARENA_MAX),
I personally would recommend running latest 2.1.x with

memory_allocator: JEMallocAllocator
memtable_allocation_type: offheap_objects

Some people will probably disagree, but it works great for us (rare long pauses sub 2 secs),
and if you’re seeing slow GC because of promotion failure of objects 131074 dwords big,
then I definitely suggest you give it a try.

> On Sep 10, 2015, at 1:43 PM, Robert Coli <rcoli@eventbrite.com> wrote:
> 
> On Thu, Sep 10, 2015 at 10:54 AM, Roman Tkachenko <roman@mailgunhq.com <mailto:roman@mailgunhq.com>>
wrote: 
> [5 second CMS GC] Is my best shot to play with JVM settings trying to tune garbage collection
then?
> 
> Yep. As a minor note, if the machines are that beefy, they probably have a lot of RAM,
you might wish to consider trying G1 GC and a larger heap.
> 
> =Rob
> 
>  


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