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From "Adam Fuchs (JIRA)" <>
Subject [jira] [Created] (ACCUMULO-4692) CompactionDriver leaves abandoned metadata scans
Date Wed, 02 Aug 2017 00:11:01 GMT
Adam Fuchs created ACCUMULO-4692:

             Summary: CompactionDriver leaves abandoned metadata scans
                 Key: ACCUMULO-4692
             Project: Accumulo
          Issue Type: Bug
          Components: fate
            Reporter: Adam Fuchs

We wrote a tool to kick off tablet compactions in the background while minimizing compaction
load per-server. The tool uses range compaction on one tablet per call. We're seeing a high
number of scans on the metadata table (~7,000 on a ~100 node cluster).

The metadata query in the isReady() method of CompactionDriver that is used to see if the
compaction has completed uses a range that goes to the end of the metadata entries for the
given table, but it stops consuming the results of the scanner at the end of the compaction
range. isReady gets called in a pretty tight loop, especially with hundreds of compactions
running concurrently. Seems like we should limit the scan to the metadata range associated
with the compaction so that the scan can get cleaned up quickly.

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