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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16876) RatioBasedCompactionPolicy ignores mayBeStuck
Date Mon, 24 Oct 2016 15:51:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15602391#comment-15602391
] 

Andrew Purtell commented on HBASE-16876:
----------------------------------------

Thanks for the feedback on the docs [~nealeyoung] . 'git diff > HBASE-16876.patch' and
attachment of that file here is all you need to do, FWIW. We can take it from there. 

> RatioBasedCompactionPolicy ignores mayBeStuck
> ---------------------------------------------
>
>                 Key: HBASE-16876
>                 URL: https://issues.apache.org/jira/browse/HBASE-16876
>             Project: HBase
>          Issue Type: Bug
>          Components: Compaction
>            Reporter: Neal Young
>              Labels: newbie
>
> I'm a newbie so may not be reporting this bug correctly.  The bug currently shows in
lines 181 - 190 here : http://hbase.apache.org/xref/org/apache/hadoop/hbase/regionserver/compactions/RatioBasedCompactionPolicy.html#181
.
> {code:title=Bar.java|borderStyle=solid}
> 176     while (countOfFiles - start >= comConf.getMinFilesToCompact() &&
> 177       fileSizes[start] > Math.max(comConf.getMinCompactSize(),
> 178           (long) (sumSize[start + 1] * ratio))) {
> 179       ++start;
> 180     }
> 181     if (start < countOfFiles) {
> 182       LOG.info("Default compaction algorithm has selected " + (countOfFiles - start)
> 183         + " files from " + countOfFiles + " candidates");
> 184     } else if (mayBeStuck) {
> 185       // We may be stuck. Compact the latest files if we can.
> 186       int filesToLeave = candidates.size() - comConf.getMinFilesToCompact();
> 187       if (filesToLeave >= 0) {
> 188         start = filesToLeave;
> 189       }
> 190     }
> {code}
> On reaching line 176, start = 0.  When comConf.getMinFilesToCompact() is at least 2 (as
occurs in the default), the while loop is guaranteed to terminate with start < countOfFiles.
 Hence, the else clause starting at line 184 never executes, regardless of the value of mayBeStuck.
> Perhaps the following code would be better, but I'm not sure:
> {code:title=Bar.java|borderStyle=solid}
>     while (start < countOfFiles
>            && fileSizes[start] > Math.max(comConf.getMinCompactSize(),
>                                           (long) (sumSize[start + 1] * ratio))) {
>         ++start;
>     }
>     if (countOfFiles - start < comConf.getMinFilesToCompact()) {
>         if (mayBeStuck && countOfFiles >= comConf.getMinFilesToCompact())
{
>             start = countOfFiles - comConf.getMinFilesToCompact();
>         } else {
>             start = countOfFiles;
>         }
>     }
>     if (countOfFiles - start > 0) {
>         LOG.info("Default compaction algorithm has selected " + (countOfFiles - start)
>                  + " files from " + countOfFiles + " candidates");
>     }
> {code}



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