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Date: Wed, 13 Apr 2016 03:54:25 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (ACCUMULO-4187) Rate limiting of major
 compactions
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    [ https://issues.apache.org/jira/browse/ACCUMULO-4187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15238561#comment-15238561 ] 

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_r59489844
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/file/streams/RateLimitedInputStream.java ---
    @@ -0,0 +1,67 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.accumulo.core.file.streams;
    +
    +import java.io.FilterInputStream;
    +import java.io.IOException;
    +import java.io.InputStream;
    +import org.apache.accumulo.core.util.ratelimit.NullRateLimiter;
    +import org.apache.accumulo.core.util.ratelimit.RateLimiter;
    +import org.apache.hadoop.fs.Seekable;
    +
    +/** A decorator for an {@code InputStream} which limits the rate at which reads are performed. */
    --- End diff --
    
    Expand the javadoc please (style-nit)


> 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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