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  1. MariaDB Server
  2. MDEV-6282

OQGraph crashes under load




      I've been updating one of my applications from OQGraphv2 to v3 and while initial tests showed everything working, I'm now getting troublesome crashes when I put some load on the OQGraph table.

      The application is basically a webservice (in PHP) that queries the OQGraph table (schema attached) and returns the result. The query in itself should be fairly simple:

      SELECT db.* FROM db_history AS db INNER JOIN version_history AS v ON db.nodeID = v.linkid WHERE origid = 1 AND destid = 3 AND latch = 'dijkstras';

      When doing single sequential requests in the browser, everything works fine. But once I started to put some load on the webservice (using siege as load testing tool), MariaDB crashes quickly after 1-2 requests (crash dump attached), always with the same crash dump.

      I should note that the database setup is a master-slave replication setup. I'm not sure that has anything to do with the crashes I'm seeing though.

      I can reproduce this fairly easily and reliably in my test environment, on both the slave and the master node, but have not been successful so far in producing a test case that does not involve running siege.


        1. backtrace_2.log
          6 kB
        2. backtrace.log
          8 kB
        3. carbon.log
          3 kB
        4. crash.log
          4 kB
        5. data.sql
          2 kB
        6. debug.log
          410 kB
        7. explain.log
          3 kB
        8. oqgraph_crash_without_latch.log
          863 kB
        9. oqgraph_load.core.tar.xz
          1.12 MB
        10. schema.sql
          0.8 kB
        11. show_variables.log
          385 kB
        12. threaddump_2.log
          61 kB
        13. threaddump.log
          88 kB
        14. valgrind.log
          10 kB
        15. variables
          69 kB

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              serg Sergei Golubchik
              pprkut Heinz Wiesinger
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