Accumulo
  1. Accumulo
  2. ACCUMULO-2889

Batch metadata table updates for new walogs

    Details

    • Type: Improvement Improvement
    • Status: Patch Available
    • Priority: Major Major
    • Resolution: Unresolved
    • Affects Version/s: 1.5.1, 1.6.0
    • Fix Version/s: None
    • Component/s: None
    • Labels:
      None

      Description

      Currently, when we update the Metadata table with new loggers, we will update the metadata for each tablet serially. We could optimize this to instead use a batchwriter to send all metadata updates for all tablets in a batch.

      A few special cases include:

      • What if the !METADATA tablet was included in the batch?
      • What about the root tablet?

      Benefit:
      In one of our clusters, we're experiencing particularly slow HDFS operations leading to large oscillations in ingest performance. We haven't isolated the cause in HDFS but when we profile the tservers, we noticed that they were waiting for metadata table operations to complete. This would target the waiting.

      Potential downsides:
      Given the existing locking scheme, it looks like we may have to lock a tablet for slightly longer (we'll lock for the duration of the batch).

      1. ACCUMULO-2889.2.patch
        33 kB
        Jonathan Park
      2. accumulo-2889_withoutpatch.png
        475 kB
        Jonathan Park
      3. accumulo-2889-withpatch.png
        464 kB
        Jonathan Park
      4. ACCUMULO-2889.1.patch
        35 kB
        Jonathan Park
      5. start-ingest.sh
        2 kB
        Jonathan Park
      6. batch_perf_test.sh
        0.5 kB
        Jonathan Park
      7. run_all.sh
        0.3 kB
        Jonathan Park
      8. ACCUMULO-2889.0.patch.txt
        30 kB
        Jonathan Park

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            • Assignee:
              Jonathan Park
              Reporter:
              Jonathan Park
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              Dates

              • Created:
                Updated:

                Development