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From Jeff Whiting <je...@qualtrics.com>
Subject Re: Region server heap used memory usage?
Date Thu, 01 Nov 2012 17:07:15 GMT
So are you looking at the total process size (e.g. top) or are you looking at the amount of
the jvm says it is using (e.g. jmap -heap <pid>)?

If you are looking at the process size (top) jvm doesn't ever give memory back so over time
process will just get bigger and bigger as it will spike in size before garbage collection
can kick 
in an free enough memory.  If you are looking at jvm memory used then it will use the memory
said + everything else "in flight".  Stuff "in flight" includes any memory for the IPC running,

memory for return values, memory for compactions, memory for general bookkeeping, etc.  The
ones would be return values (and put values) for IPC and memory used for compactions.


On 11/1/2012 8:43 AM, 徐歷盛 wrote:
>   What's the usage of region server heap used memory ?
> I originally thought it's roughly the sum of current memstore + blockcache
> + storefileindex. But in our environment, I have configured max heap to 20g
> , heap used memory is sometimes up to 19g. At that moment, storefileindex
> was 8g, blockcache was 1g, memstore was 1g. What's the rest 9g memory ?
> Thanks in advance.

Jeff Whiting
Qualtrics Senior Software Engineer

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