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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 03:44:25 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15238548#comment-15238548
] 

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

Github user joshelser commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/90#discussion_r59489344
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/file/blockfile/impl/CachableBlockFile.java
---
    @@ -139,11 +146,12 @@ public long getStartPos() throws IOException {
        *
        */
       public static class Reader implements BlockFileReader {
    +    private final RateLimiter readLimiter;
         private BCFile.Reader _bc;
         private String fileName = "not_available";
         private BlockCache _dCache = null;
         private BlockCache _iCache = null;
    -    private FSDataInputStream fin = null;
    +    private Closeable fin = null;
    --- End diff --
    
    Any reason for `Closeable` instead of `InputStream`?


> 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
>    Affects Versions: 1.8.0
>            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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