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  1. MariaDB Server
  2. MDEV-7121

Parallel slave may hang if master crashes in the middle of writing transaction to binlog

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          Description

          This bug happens on the slave, when a binlog from a master ends with a
          partially written event group (that has BEGIN but is missing COMMIT, eg).
          Such partial event group occurs if the master crashes in the middle of writing
          to the binlog.

          The slave detects this when the restart format description event in the
          following binlog file is received. A worker thread that is in the middle of
          replicating the partial event group must be notified so that it can roll back
          the transaction.

          The bug was that this notification could be lost, depending on thread
          scheduling. If lost, the worker thread would then wait indefinitely for the
          rest of the transaction to arrive, and the SQL thread in turn would wait for
          the worker thread to complete the rollback, deadlocking the slave.

          This bug is likely what was seen by a user in a hard-to-reproduce hang.

          It is also the cause of the sporadic failure in Buildbot in MDEV-7079.

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                relates to

                Bug - A problem which impairs or prevents the functions of the product. MDEV-7079 rpl.rpl_parallel_temptable fails sporadically in standard buildbot tests and persistently in valgrind builder

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

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                  knielsen Kristian Nielsen added a comment -

                  http://lists.askmonty.org/pipermail/commits/2014-November/007034.html

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                  knielsen Kristian Nielsen added a comment - http://lists.askmonty.org/pipermail/commits/2014-November/007034.html

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                    • Assignee:
                      knielsen Kristian Nielsen
                      Reporter:
                      knielsen Kristian Nielsen
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                      • Created:
                        Updated:
                        Resolved: