[ 
https://issues.apache.org/jira/browse/HBASE-3694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13015272#comment-13015272
 ] 

Liyin Tang commented on HBASE-3694:
-----------------------------------

yes, please review:)

> high multiput latency due to checking global mem store size in a synchronized 
> function
> --------------------------------------------------------------------------------------
>
>                 Key: HBASE-3694
>                 URL: https://issues.apache.org/jira/browse/HBASE-3694
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Liyin Tang
>            Assignee: Liyin Tang
>         Attachments: 3694-cliffs-counter.txt, Hbase-3694[r1085306], 
> Hbase-3694[r1085306]_2.patch, Hbase-3694[r1085306]_3.patch, 
> Hbase-3694[r1085508]_4.patch, Hbase-3694[r1085592]_7.patch, 
> Hbase-3694[r1085593]_5.patch, Hbase-3694[r1085593]_6.patch
>
>
> The problem is we found the multiput latency is very high.
> In our case, we have almost 22 Regions in each RS and there are no flush 
> happened during these puts.
> After investigation, we believe that the root cause is the function 
> getGlobalMemStoreSize, which is to check the high water mark of mem store. 
> This function takes almost 40% of total execution time of multiput when 
> instrumenting some metrics in the code.  
> The actual percentage may be more higher. The execution time is spent on 
> synchronize contention.
> One solution is to keep a static var in HRegion to keep the global MemStore 
> size instead of calculating them every time.
> Why using static variable?
> Since all the HRegion objects in the same JVM share the same memory heap, 
> they need to share fate as well.
> The static variable, globalMemStroeSize, naturally shows the total mem usage 
> in this shared memory heap for this JVM.
> If multiple RS need to run in the same JVM, they still need only one 
> globalMemStroeSize.
> If multiple RS run on different JVMs, everything is fine.
> After changing, in our cases, the avg multiput latency decrease from 60ms to 
> 10ms.
> I will submit a patch based on the current trunk.

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira

Reply via email to