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  1. MariaDB Server
  2. MDEV-20628

If temporary error occurs with optimistic mode of parallel replication, error message has false information

Details

    • Bug
    • Status: Closed (View Workflow)
    • Critical
    • Resolution: Duplicate
    • 10.2.27
    • N/A
    • Replication
    • None

    Description

      With optimistic mode of parallel replication, if a query fails, then you can end up with log messages like this:

      2019-09-17 19:27:07 140190015801088 [ERROR] Slave (additional info): Commit failed due to failure of an earlier commit on which this one depends Error_code: 1964
      		 
      2019-09-17 19:27:07 140190015801088 [Warning] Slave: Duplicate entry '...' for key 'name' Error_code: 1062
      		 
      2019-09-17 19:27:07 140190015801088 [Warning] Slave: Deadlock found when trying to get lock; try restarting transaction Error_code: 1213
      		 
      2019-09-17 19:27:07 140190015801088 [Warning] Slave: Commit failed due to failure of an earlier commit on which this one depends Error_code: 1964
      		 
      2019-09-17 19:27:07 140190015801088 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'mariadb-bin.000001' position 50284765; GTID position '0-1-119489'
      		 
      2019-09-17 19:27:07 140190315325184 [ERROR] Slave (additional info): Commit failed due to failure of an earlier commit on which this one depends Error_code: 1964
      		 
      2019-09-17 19:27:07 140190315325184 [Warning] Slave: Deadlock found when trying to get lock; try restarting transaction Error_code: 1213
      		 
      2019-09-17 19:27:07 140190315325184 [Warning] Slave: Connection was killed Error_code: 1927
      		 
      2019-09-17 19:27:07 140190315325184 [Warning] Slave: Deadlock found when trying to get lock; try restarting transaction Error_code: 1213
      		 
      2019-09-17 19:27:07 140190315325184 [Warning] Slave: Commit failed due to failure of an earlier commit on which this one depends Error_code: 1964
      		 
      2019-09-17 19:27:07 140190315325184 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'mariadb-bin.000001' position 50284765; GTID position '0-1-119489'

      These messages are printed in slave_output_error_info. See here:

      https://github.com/MariaDB/server/blob/mariadb-10.2.27/sql/slave.cc#L4756

      With optimistic mode of parallel replication, the slave_output_error_info function can be called when a transaction has failed because another transaction that it depends on has failed. See here:

      https://github.com/MariaDB/server/blob/mariadb-10.2.27/sql/rpl_parallel.cc#L1221

      Some errors are considered "temporary errors". The only temporary errors are currently just deadlocks and timeouts. See here:

      https://github.com/MariaDB/server/blob/mariadb-10.2.27/sql/slave.cc#L3381

      In the case of a "temporary error", the event group can actually be retried. See here:

      https://github.com/MariaDB/server/blob/mariadb-10.2.27/sql/rpl_parallel.cc#L1305

      These retries happen if slave_transaction_retries is greater than 0.

      https://mariadb.com/kb/en/library/replication-and-binary-log-system-variables/#slave_transaction_retries

      In the example shown above, the errors were deadlocks, so the transactions were indeed retried. Notice that the following message was still included in the above log snippet:

      2019-09-17 19:27:07 140190315325184 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'mariadb-bin.000001' position 50284765; GTID position '0-1-119489'

      This message is not quite correct in this case.

      • The SQL thread was not aborted.
      • The SQL thread does not need to be manually restarted.

      It seems like this error message in slave_output_error_info should be slightly different if the SQL thread encounters a temporary error. In that case, maybe it should be a Warning instead of an Error, and maybe it should say something like this instead:

      2019-09-17 19:27:07 140190315325184 [Warning] Temporary error running query. The slave SQL thread will retry the query. We encountered the temporary error at log 'mariadb-bin.000001' position 50284765; GTID position '0-1-119489'

      Attachments

        Issue Links

          is blocked by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-33303 slave_parallel_mode=optimistic should not report the mode's specific temporary errors

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

          Bug - A problem which impairs or prevents the functions of the product. MDEV-13577 slave_parallel_mode=optimistic should not report the mode's specific temporary errors

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-30010 Slave (additional info): Commit failed due to failure of an earlier commit on which this one depends Error_code: 1964

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-20604 Duplicate key value is silently truncated to 64 characters in print_keydup_error

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

          Bug - A problem which impairs or prevents the functions of the product. MDEV-20605 Awaken transaction can miss inserted by other transaction records due to wrong persistent cursor restoration

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

          Activity

            Transition Time In Source Status Execution Times
            Julien Fritsch made transition -
            Open Closed
            		386d 9h 53m 1

            People

              sachin.setiya.007 Sachin Setiya (Inactive)
              GeoffMontee Geoff Montee (Inactive)
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              Dates

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                Updated:
                Resolved:

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