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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HBASE-13082) Coarsen StoreScanner locks to RegionScanner
Date Wed, 11 Nov 2015 11:31:11 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13082?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15000264#comment-15000264
] 

ramkrishna.s.vasudevan edited comment on HBASE-13082 at 11/11/15 11:31 AM:
---------------------------------------------------------------------------

Withpatch
=======
Avg: 324secs
Withoutpatch
===========
Avg : 410secs
Using the command
{code}
./hbase org.apache.hadoop.hbase.PerformanceEvaluation --nomapred --oneCon=true  --caching=5000
--filterAll=true --rows=10000  scanRange10000 50
{code}
With YCSB scanRange can see that there is no significant gain because of network bottleneck
but there is no degrade. 
Withpatch
========
[OVERALL], Throughput(ops/sec), 3752.08334427691
Withoutpatch
==========
[OVERALL], Throughput(ops/sec), 3723.210569152307





was (Author: ram_krish):
Withpatch
=======
Avg: 324secs
Withoutpatch
===========
Avg : 410secs
Using the command
{code}
./hbase org.apache.hadoop.hbase.PerformanceEvaluation --nomapred --oneCon=true  --caching=5000
--filterAll=true --rows=10000  scanRange10000 50
{code}
With YCSB scanRange can see that there is no significant gain because of network bottleneck
but there is no degrade. 
Withpatch
========
[OVERALL], Throughput(ops/sec), 3723.210569152307
Withoutpatch
==========
[OVERALL], Throughput(ops/sec), 3752.08334427691



> Coarsen StoreScanner locks to RegionScanner
> -------------------------------------------
>
>                 Key: HBASE-13082
>                 URL: https://issues.apache.org/jira/browse/HBASE-13082
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Assignee: ramkrishna.s.vasudevan
>         Attachments: 13082-test.txt, 13082-v2.txt, 13082-v3.txt, 13082-v4.txt, 13082.txt,
13082.txt, HBASE-13082.pdf, HBASE-13082_1.pdf, HBASE-13082_12.patch, HBASE-13082_13.patch,
HBASE-13082_14.patch, HBASE-13082_1_WIP.patch, HBASE-13082_2.pdf, HBASE-13082_2_WIP.patch,
HBASE-13082_3.patch, HBASE-13082_4.patch, HBASE-13082_9.patch, HBASE-13082_9.patch, gc.png,
gc.png, gc.png, hits.png, next.png, next.png
>
>
> Continuing where HBASE-10015 left of.
> We can avoid locking (and memory fencing) inside StoreScanner by deferring to the lock
already held by the RegionScanner.
> In tests this shows quite a scan improvement and reduced CPU (the fences make the cores
wait for memory fetches).
> There are some drawbacks too:
> * All calls to RegionScanner need to be remain synchronized
> * Implementors of coprocessors need to be diligent in following the locking contract.
For example Phoenix does not lock RegionScanner.nextRaw() and required in the documentation
(not picking on Phoenix, this one is my fault as I told them it's OK)
> * possible starving of flushes and compaction with heavy read load. RegionScanner operations
would keep getting the locks and the flushes/compactions would not be able finalize the set
of files.
> I'll have a patch soon.



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