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  1. MariaDB Server
  2. MDEV-21018

CPU Spikes to 50% and does not let up with RocksDB enabled

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    Details

    • Type: Bug
    • Status: Open (View Workflow)
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 10.2.26, 10.3.17, 10.2.29, 10.3.20, 10.4.7, 10.4.10
    • Fix Version/s: 10.2, 10.3, 10.4
    • Labels:
      None
    • Environment:
      Encountered on Windows, debugged on Windows.

      Description

      When upgrading to 10.4.7 and continuing on through 10.4.10 (and equivalent version of 10.2 and 10.3), if I have the RocksDB plugin enabled:

      [mysqld]
      ...
      plugin_load_add = ha_rocksdb
      

      Then as soon as I start that instance (a service in my case), the CPU usage spikes to 50% and does not let up until I kill the process.

      It may dip to 48-49%.

      If I start a second instance, they both end up taking ~49-50% each, and the CPU is pegged at 100%.

      If I start a third instance, the 3 generally end up using about ~32-33% each, and the CPU is pegged at 100%.

      The instances were only using about 32M RAM, and zero activity was occurring on them.

      I started Windows profiler, and attached it (and CPU stats gatherer), allowed it to run for 50 seconds, and analyzed. It showed that the CPU usage came from ha_rocksdb.dll.

      I then commented out the RocksDB plugin:

      #plugin_load_add = ha_rocksdb
      

      Restarted MariaDB.

      And then CPU was back to normal, roughly 0% in this case, since there was 0 activity.

      Comment: It is easy to remove if you enabled the plugin via the config file: simply remove or comment out the line, as above, and restart MariaDB.

      If you enabled it via the command line, then you need to uninstall it via the command line:

      UNINSTALL SONAME 'ha_rocksdb';
      

      However, this command is just hanging for me in this situation (i.e., when CPU is pegged out). It is essentially stuck. It did finally complete after about 20 minutes

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            Assignee:
            psergey Sergei Petrunia
            Reporter:
            ccalender Chris Calender
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              Dates

              Created:
              Updated: