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From "Ryan McGuire (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5534) Writing wide row causes high CPU usage after compaction
Date Fri, 03 May 2013 01:15:14 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13648087#comment-13648087
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Ryan McGuire commented on CASSANDRA-5534:
-----------------------------------------

The bisect brought me back to a950b9257f4c92d067eb5e1d437096699123ac9b which is from [CASSANDRA-5125|https://issues.apache.org/jira/browse/CASSANDRA-5125]
- that's the first instance where this slowdown occurs.
                
> Writing wide row causes high CPU usage after compaction
> -------------------------------------------------------
>
>                 Key: CASSANDRA-5534
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5534
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 2.0
>            Reporter: Ryan McGuire
>            Assignee: Jonathan Ellis
>         Attachments: wide_row_stress.trunk.log.txt.gz
>
>
> Introduced in commit e74c13ff08663d306dcc5cdc99c07e9e6c12ca21 there is a significant
slow down when creating a wide row with cassandra-stress:
> Testing with the prior (good) commit I used this to write a single wide row, which completed
rather quickly:
> {code}
> $ ccm create -v git:60f09f0121e0801851b9ab017eddf7e326fa05fb wide-row
> Fetching Cassandra updates...
> Cloning Cassandra (from local cache)
> Checking out requested branch (60f09f0121e0801851b9ab017eddf7e326fa05fb)
> Compiling Cassandra 60f09f0121e0801851b9ab017eddf7e326fa05fb ...
> Current cluster is now: wide-row
> $ ccm populate -n 1
> $ ccm start
> $ time ccm node1 stress -c 10000 -S 1000 -n 1
> Created keyspaces. Sleeping 1s for propagation.
> total,interval_op_rate,interval_key_rate,latency/95th/99th,elapsed_time
> 1,0,0,273.3,273.3,273.3,0
> END
> real	0m7.106s
> user	0m1.710s
> sys	0m0.120s
> {code}
> Using the bugged commit (e74c13ff08663d306dcc5cdc99c07e9e6c12ca21) I get a significant
slow down:
> {code}
> 02:42 PM:~$ ccm create -v git:e74c13ff08663d306dcc5cdc99c07e9e6c12ca21 wide-row
> Fetching Cassandra updates...
> Current cluster is now: wide-row
> 02:42 PM:~$ ccm populate -n 1
> 02:42 PM:~$ ccm start
> 02:42 PM:~$ time ccm node1 stress -c 10000 -S 1000 -n 1
> Created keyspaces. Sleeping 1s for propagation.
> total,interval_op_rate,interval_key_rate,latency,95th,99th,elapsed_time
> 1,0,0,423.2,423.2,423.2,0
> Total operation time      : 00:00:00
> END
> real	4m16.394s
> user	0m2.230s
> sys	0m0.137s
> {code}
> Interestingly, the commit in question just says it's a merge from cassandra-1.2, but
I do not see this same slowdown using that branch, this only occurs in trunk.

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