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From "Neal Young (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-16876) RatioBasedCompactionPolicy ignores mayBeStuck
Date Tue, 18 Oct 2016 22:16:58 GMT
Neal Young created HBASE-16876:
----------------------------------

             Summary: 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


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 (start < countOfFiles) {
        if (countOfFiles - start >= comConf.getMinFilesToCompact()) {
            LOG.info("Default compaction algorithm has selected " + (countOfFiles - start)
                     + " files from " + countOfFiles + " candidates");
        } else {
            start = countOfFiles;
        }
    } else if (mayBeStuck) {
        // We may be stuck. Compact the latest files if we can.
        int filesToLeave = candidates.size() - comConf.getMinFilesToCompact();
        if (filesToLeave >= 0) {
            start = filesToLeave;
        }
    }
{code}




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