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  1. MariaDB Server
  2. MDEV-7929

record_gtid() for non-transactional event group calls wakeup_subsequent_commits() too early, causing slave hang

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          Description

          This was found together with MDEV-7888, but it is a logically different bug,
          so filing separately.

          The parallel replication worker threads can hang in some cases with
          non-transactional event groups. The symptom is that worker threads are stuck
          in "waiting for prior transaction to start commit".

          The problem is when record_gtid() runs at the end of the non-transactional
          update. Then it needs to create its own transaction to update the
          mysql.gtid_slave_pos table. This causes ha_commit_trans() to call
          wakeup_subsequent_commits(). But this is wrong, it is too early.

          The hang then occurs because a following transaction things the prior
          non-transactional event group is already done - so it deallocates the
          corresponding group_commit_orderer object. Then a following worker thread does
          not get its wakeup, and the slave gets stuck.

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                Bug - A problem which impairs or prevents the functions of the product. MDEV-7888 ANALYZE TABLE does wakeup_subsequent_commits(), causing wrong binlog order and parallel replication hang

                • Major - Major loss of function.
                • Closed

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                  knielsen Kristian Nielsen added a comment -

                  http://lists.askmonty.org/pipermail/commits/2015-April/007723.html

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                  knielsen Kristian Nielsen added a comment - http://lists.askmonty.org/pipermail/commits/2015-April/007723.html
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                  knielsen Kristian Nielsen added a comment -

                  10.1-specific part:

                  http://lists.askmonty.org/pipermail/commits/2015-April/007724.html

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                  knielsen Kristian Nielsen added a comment - 10.1-specific part: http://lists.askmonty.org/pipermail/commits/2015-April/007724.html

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