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  1. MariaDB Server
  2. MDEV-36887

Reevaluate fix for MDEV-20946 (mdl deadlock overweight)

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Details

    • Bug
    • Status: Open (View Workflow)
    • Major
    • Resolution: Unresolved
    • 10.4.19, 10.5.10, 10.11.0, 10.6, 10.7(EOL), 10.8(EOL), 10.9(EOL), 10.10(EOL), 11.0(EOL), 11.1(EOL), 11.2(EOL), 11.3(EOL), 11.4, 11.5(EOL), 11.6(EOL), 11.7(EOL), 11.8, 12.0
    • 12.1
    • Locking

    Description

      Normally MDL subsystem prefers DML (over DDL) as a deadlock victim. MDEV-20946 (commit fa5f60681fe4) introduced concept of "deadlock overweight", which can turn things upside down. Now DDL can fall as deadlock victim. While it was intended only to fix FTWRL issue. Consequences are to be analysed.

      Also deadlock overweight is not reset between statements. Allowing subsequent statements to "inherit" modified value. An attempt to fix similar issue was performed in MDEV-27523 (e46ae5926503), but it reset the value for subsequent connections only.

      Hit this while debugging test case for MDEV-28567. It relies on incorrect behaviour described above.

      Attachments

        Issue Links

          is caused by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-20946 Hard FTWRL deadlock under user level locks

          • Major - Major loss of function.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-29474 main.lock_sync fails with timeout

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

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              svoj Sergey Vojtovich
              svoj Sergey Vojtovich
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              Dates

                Created:
                Updated:

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