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  1. MariaDB Server
  2. MDEV-33327

rpl_seconds_behind_master_spike Sensitive to IO Thread Stop Position




      The test rpl.rpl_seconds_behind_master_spike can fail with

      CURRENT_TEST: rpl.rpl_seconds_behind_master_spike
      mysqltest: At line 63: query 'select count(*)=1 from t1' failed: ER_NO_SUCH_TABLE (1146): Table 'test.t1' doesn't exist
      The result from queries just before the failure was:
      < snip >
      SET @@global.debug_dbug="+d,pause_sql_thread_on_fde,negate_clock_diff_with_master";
      # Future events must be logged at least 2 seconds after
      # the slave starts
      connection master;
      # Write events to ensure slave will be consistent with master
      create table t1 (a int);
      insert into t1 values (1);
      # Flush logs on master forces slave to generate a Format description
      # event in its relay log
      flush logs;
      connection slave;
      # Ignore FDEs that happen before the CREATE/INSERT commands
      SET DEBUG_SYNC='now WAIT_FOR paused_on_fde';
      SET DEBUG_SYNC='now SIGNAL sql_thread_continue';
      SET DEBUG_SYNC='now WAIT_FOR paused_on_fde';
      SET DEBUG_SYNC='now SIGNAL sql_thread_continue';
      # On the next FDE, the slave should have the master CREATE/INSERT events
      SET DEBUG_SYNC='now WAIT_FOR paused_on_fde';
      select count(*)=1 from t1;

      because the test is reliant on a specific number of format descriptor events (FDEs). However, depending on when the IO thread is stopped, it can send an extra FDE before sending the transactions, forcing the test to pause before executing any transactions.

      The test should be fixed to be more flexible and not reliant on FDE count.

      Note this test became much more unstable after MDEV-32551, as the amended kill_zombie_dump_threads would kill the IO thread quicker, making this test fail quite often.


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              bnestere Brandon Nesterenko
              bnestere Brandon Nesterenko
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