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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4187) Rate limiting of major compactions
Date Wed, 13 Apr 2016 21:08:25 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15240017#comment-15240017
] 

ASF GitHub Bot commented on ACCUMULO-4187:
------------------------------------------

Github user keith-turner commented on the pull request:

    https://github.com/apache/accumulo/pull/90#issuecomment-209647745
  
    I played around with this branch locally.  I created a table with 10,000,000 entries using
test_ingest using the following commands. 
    
    ```
    ./bin/accumulo shell -u root -p secret -e "createtable test_ingest"
    ./bin/accumulo org.apache.accumulo.test.TestIngest -u root -p secret --timestamp 1 --size
50 --random 56 --rows 10000000 --start 0 --cols 1 --instance instance16
    ```
    I set the rate limit to 5M and forced a compaction.  I saw the following in the tserver
logs.
    
    ```
    Compaction 2<< 10,000,000 read | 10,000,000 written | 122,925 entries/sec | 81.350
secs |  431,758,096 bytes | 5307413.596 byte/sec
    ```
    
    Then I split the table into 8 tablets and forced a compaction to test the rate limit for
multiple threads.  I had the default of 3 compaction threads.  I saw the following in the
logs for this test.
    
    ```
    Compaction 2;row_0003749;row_00025 1,249,000 read | 1,249,000 written | 41,866 entries/sec
| 29.833 secs |   53,926,291 bytes | 1807605.370 byte/sec
    Compaction 2;row_00025;row_000125 1,250,000 read | 1,250,000 written | 41,899 entries/sec
| 29.833 secs |   53,970,229 bytes | 1809078.168 byte/sec
    Compaction 2;row_000125< 1,250,000 read | 1,250,000 written | 41,783 entries/sec |
29.916 secs |   53,969,343 bytes | 1804029.382 byte/sec
    Compaction 2;row_000625;row_0005 1,250,000 read | 1,250,000 written | 42,134 entries/sec
| 29.667 secs |   53,970,847 bytes | 1819221.593 byte/sec
    Compaction 2;row_0005;row_0003749 1,251,000 read | 1,251,000 written | 42,109 entries/sec
| 29.708 secs |   54,012,874 bytes | 1818125.555 byte/sec
    Compaction 2;row_00075;row_000625 1,250,000 read | 1,250,000 written | 41,881 entries/sec
| 29.846 secs |   53,969,549 bytes | 1808267.406 byte/sec
    Compaction 2;row_000875;row_00075 1,250,000 read | 1,250,000 written | 63,909 entries/sec
| 19.559 secs |   53,969,511 bytes | 2759318.523 byte/sec
    Compaction 2<;row_000875 1,250,000 read | 1,250,000 written | 63,798 entries/sec |
19.593 secs |   53,969,987 bytes | 2754554.535 byte/sec
    ```
    
    



> Rate limiting of major compactions
> ----------------------------------
>
>                 Key: ACCUMULO-4187
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4187
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: core, tserver
>            Reporter: Shawn Walker
>            Assignee: Shawn Walker
>            Priority: Minor
>             Fix For: 1.8.0
>
>
> In discussing [ACCUMULO-4166] with Keith Turner, we decided that the underlying issue
is that major compactions can overwhelm a tablet server, rendering it nearly unresponsive.
> To address this, we should take a cue from Apache Cassandra and restrict how quickly
we perform major compactions.  Rate limiting reads and writes involved in major compactions
will directly affect the IO load caused by major compactions, and should also indirectly affect
the CPU load.



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