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  1. MariaDB Server
  2. MDEV-5810

OQGRAPH causes MariaDB 100% CPU usage

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Duplicate
    • Affects Version/s: 10.0.8
    • Fix Version/s: None
    • Component/s: None
    • Labels:
    • Environment:
      Debian Wheezy
      MariaDB 10.0.8 (query cache disabled)

      Description

      This does not happen every time, unfortunately. I've tried to google this issue - 've found similar problems, but most of them revolve around MariaDB 5 series with OQGRAPH v2, not v3.

      Create a test database with the information listed here:

      https://mariadb.com/kb/en/oqgraph-overview/

      MariaDB [test]> SELECT * FROM oq_graph;
      Killed

      It takes over a minute for it to return "Killed", all the while mysqld uses as much CPU as possible. But then, if I try to access it again:

      MariaDB [test]> SELECT * FROM oq_graph;
      ERROR 2013 (HY000): Lost connection to MySQL server during query
      MariaDB [test]> SELECT * FROM oq_graph;
      ERROR 2006 (HY000): MySQL server has gone away
      No connection. Trying to reconnect...
      Connection id:    3
      Current database: test
       
      +-------+--------+--------+--------+------+--------+
      | latch | origid | destid | weight | seq  | linkid |
      +-------+--------+--------+--------+------+--------+
      | NULL  |      1 |      2 |      1 | NULL |   NULL |
      | NULL  |      2 |      3 |      1 | NULL |   NULL |
      | NULL  |      2 |      6 |      1 | NULL |   NULL |
      | NULL  |      3 |      4 |      1 | NULL |   NULL |
      | NULL  |      4 |      5 |      1 | NULL |   NULL |
      | NULL  |      5 |      6 |      1 | NULL |   NULL |
      +-------+--------+--------+--------+------+--------+
      6 rows in set (0.02 sec)

      And then sometimes, it works as expected.

      Accessing from PHP or Python has the same effect: 100% CPU load. I've yet to get a proper result returned from these environments.

      Selecting from oq_backing works fine.

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              Assignee:
              andymc73 Andrew McDonnell
              Reporter:
              blitzmann Ryan Holmes (Inactive)
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                Updated:
                Resolved:

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