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From Romain Hardouin <>
Subject Re: Attached profiled data but need help understanding it
Date Mon, 27 Feb 2017 18:30:54 GMT
Regarding shared pool workers see CASSANDRA-11966. You may have to backport it depending on
your Cassandra version. 
Did you try to lower compaction throughput to see if it helps? Be sure to keep an eye on pending
compactions, SSTables count and SSTable per read of course.
"alloc" is the memory allocation rate. You can see that compactions are GC intensive.
You won't be able to achieve impressive writes/s with LWT. But maybe there is room for improvement.
Try GC tuning, different pool sizes for NTR, concurrent reads and writes, compaction executors,
etc. Also check if you can improve network latency (e.g. VF or ENA on AWS).
What LWT rate would you want to achieve?

    Le Lundi 27 février 2017 12h48, Kant Kodali <> a écrit :

 Also Attached is a flamed graph generated from a thread dump.
On Mon, Feb 27, 2017 at 2:32 AM, Kant Kodali <> wrote:

Attached are the stats of my Cassandra node running on a 4-core CPU. I am using sjk-plus tool
for the first time so what are the things I should watched out for in my attached screenshot?
I can see the CPU is almost maxed out but should I say that is because of compaction or shared-worker-pool
threads (which btw, I dont know what they are doing perhaps I need to take threadump)? Also
what is alloc for each thread? 
I have a insert heavy workload (almost like an ingest running against cassandra cluster) and
in my case all writes are LWT.
The current throughput is 1500 writes/sec where each write is about 1KB. How can I tune something
for a higher throughput? Any pointers or suggestions would help.

Thanks much,kant

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