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Date: Fri, 11 Sep 2015 11:22:45 +0000 (UTC)
From: "Hadoop QA (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12764341.1419995983000.312962.1441970565816@Atlassian.JIRA>
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Subject: [jira] [Commented] (HBASE-12790) Support fairness across
 parallelized scans
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    [ https://issues.apache.org/jira/browse/HBASE-12790?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14740598#comment-14740598 ] 

Hadoop QA commented on HBASE-12790:
-----------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12755372/HBASE-12790_trunk_1.patch
  against master branch at commit fda317cebb5d306cabf1899e05cedb0225b2b62b.
  ATTACHMENT ID: 12755372

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:green}+1 tests included{color}.  The patch appears to include 10 new or modified tests.

    {color:green}+1 hadoop versions{color}. The patch compiles with all supported hadoop versions (2.4.0 2.4.1 2.5.0 2.5.1 2.5.2 2.6.0 2.7.0 2.7.1)

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of javac compiler warnings.

    {color:green}+1 protoc{color}.  The applied patch does not increase the total number of protoc compiler warnings.

    {color:red}-1 javadoc{color}.  The javadoc tool appears to have generated 3 warning messages.

                {color:red}-1 checkstyle{color}.  The applied patch generated 1837 checkstyle errors (more than the master's current 1834 errors).

    {color:green}+1 findbugs{color}.  The patch does not introduce any  new Findbugs (version 2.0.3) warnings.

    {color:red}-1 release audit{color}.  The applied patch generated 1 release audit warnings (more than the master's current 0 warnings).

    {color:red}-1 lineLengths{color}.  The patch introduces the following lines longer than 100:
    +              new java.lang.String[] { "Column", "Attribute", "StartRow", "StopRow", "Filter", "TimeRange", "MaxVersions", "CacheBlocks", "BatchSize", "MaxResultSize", "StoreLimit", "StoreOffset", "LoadColumnFamiliesOnDemand", "Small", "Reversed", "Consistency", "Caching", "GroupingId", });
+      queues.add((BlockingQueue<CallRunnerWrapper>) ReflectionUtils.newInstance(queueClass, initargs));
+      scheduler = new RoundRobinRPCScheduler(schedConf, 1, 1, 1, priority, HConstants.QOS_THRESHOLD);
+    AbstractPriorityBasedRoundRobinQueue<TestObject> testList = new AbstractRoundRobinPriorityQueueImpl(

  {color:green}+1 site{color}.  The mvn post-site goal succeeds with this patch.

     {color:red}-1 core tests{color}.  The patch failed these unit tests:
                       org.apache.hadoop.hbase.client.TestOperation

Test results: https://builds.apache.org/job/PreCommit-HBASE-Build/15558//testReport/
Release audit warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/15558//artifact/patchprocess/patchReleaseAuditWarnings.txt
Release Findbugs (version 2.0.3) 	warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/15558//artifact/patchprocess/newFindbugsWarnings.html
Checkstyle Errors: https://builds.apache.org/job/PreCommit-HBASE-Build/15558//artifact/patchprocess/checkstyle-aggregate.html

                Javadoc warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/15558//artifact/patchprocess/patchJavadocWarnings.txt
Console output: https://builds.apache.org/job/PreCommit-HBASE-Build/15558//console

This message is automatically generated.

> Support fairness across parallelized scans
> ------------------------------------------
>
>                 Key: HBASE-12790
>                 URL: https://issues.apache.org/jira/browse/HBASE-12790
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: James Taylor
>            Assignee: ramkrishna.s.vasudevan
>              Labels: Phoenix
>         Attachments: AbstractRoundRobinQueue.java, HBASE-12790.patch, HBASE-12790_1.patch, HBASE-12790_5.patch, HBASE-12790_callwrapper.patch, HBASE-12790_trunk_1.patch
>
>
> Some HBase clients parallelize the execution of a scan to reduce latency in getting back results. This can lead to starvation with a loaded cluster and interleaved scans, since the RPC queue will be ordered and processed on a FIFO basis. For example, if there are two clients, A & B that submit largish scans at the same time. Say each scan is broken down into 100 scans by the client (broken down into equal depth chunks along the row key), and the 100 scans of client A are queued first, followed immediately by the 100 scans of client B. In this case, client B will be starved out of getting any results back until the scans for client A complete.
> One solution to this is to use the attached AbstractRoundRobinQueue instead of the standard FIFO queue. The queue to be used could be (maybe it already is) configurable based on a new config parameter. Using this queue would require the client to have the same identifier for all of the 100 parallel scans that represent a single logical scan from the clients point of view. With this information, the round robin queue would pick off a task from the queue in a round robin fashion (instead of a strictly FIFO manner) to prevent starvation over interleaved parallelized scans.


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