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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 16:24:25 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15239534#comment-15239534
] 

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_r59579078
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/file/FileOperations.java ---
    @@ -55,23 +56,24 @@ public static FileOperations getInstance() {
        */
     
       public abstract FileSKVIterator openReader(String file, Range range, Set<ByteSequence>
columnFamilies, boolean inclusive, FileSystem fs, Configuration conf,
    -      AccumuloConfiguration tableConf) throws IOException;
    +      RateLimiter readLimiter, AccumuloConfiguration tableConf) throws IOException;
     
       public abstract FileSKVIterator openReader(String file, Range range, Set<ByteSequence>
columnFamilies, boolean inclusive, FileSystem fs, Configuration conf,
    -      AccumuloConfiguration tableConf, BlockCache dataCache, BlockCache indexCache) throws
IOException;
    +      RateLimiter readLimiter, AccumuloConfiguration tableConf, BlockCache dataCache,
BlockCache indexCache) throws IOException;
     
       /**
        * Open a reader that fully support seeking and also enable any optimizations related
to seeking, like bloom filters.
        *
        */
     
    -  public abstract FileSKVIterator openReader(String file, boolean seekToBeginning, FileSystem
fs, Configuration conf, AccumuloConfiguration acuconf)
    -      throws IOException;
    +  public abstract FileSKVIterator openReader(String file, boolean seekToBeginning, FileSystem
fs, Configuration conf, RateLimiter readLimiter,
    --- End diff --
    
    > In many parts of our internal code, I would prefer we grab what we need from AccumuloConfiguration,
combine it with any additional configuration appropriate for that specific context, and create
a new context-specific configuration object to pass around within that context.
    
    Somehow get the RateLimiterFactory directly from the config? That'd be a stop-gap.
    
    > I was thinking perhaps a fluent syntax for opening readers/writers would make sense.
    > That said, introducing such a change seemed a bit ambitious.
    
    Yeah, I totally understand. Finding some middle ground to avoid lots of unrelated changes
to your actual feature is ideal.


> 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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