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MDEV-15152 Optimistic parallel slave doesnt cope well with START SLAVE UNTIL

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The immediate bug was caused by a failure to recognize a correct
position to stop the slave applier run in optimistic parallel mode.
There were the following set of issues that the analysis unveil.
1 incorrect estimate for the event binlog position passed to
  is_until_satisfied
2 wait for workers to complete by the driver thread did not account non-group events
  that could be left unprocessed and thus to mix up the last executed
  binlog group's file and position:
  the file remained old and the position related to the new rotated file
3 incorrect 'slave reached file:pos' by the parallel slave report in the error log
4 relay log UNTIL missed out the parallel slave branch in
  is_until_satisfied.

The patch addresses all of them to simplify logics of log change
notification in either the master and relay-log until case.
P.1 is addressed with passing the event into is_until_satisfied()
for proper analisis by the function.
P.2 is fixed by changes in handle_queued_pos_update().
P.4 required removing relay-log change notification by workers.
Instead the driver thread updates the notion of the current relay-log
fully itself with aid of introduced
bool Relay_log_info::until_relay_log_names_defer.

An extra print out of the requested until file:pos is arranged
with --log-warning=3.
This commit is contained in:
Andrei Elkin
2020-05-05 20:32:32 +03:00
parent 451bfcd6bb
commit 0c1f97b3ab
6 changed files with 859 additions and 20 deletions
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6
sql/rpl_parallel.cc
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@ -75,18 +75,18 @@ handle_queued_pos_update(THD *thd, rpl_parallel_thread::queued_event *qev)
/* Do not update position if an earlier event group caused an error abort. */
DBUG_ASSERT(qev->typ == rpl_parallel_thread::queued_event::QUEUED_POS_UPDATE);
rli= qev->rgi->rli;
e= qev->entry_for_queued;
if (e->stop_on_error_sub_id < (uint64)ULONGLONG_MAX || e->force_abort)
if (e->stop_on_error_sub_id < (uint64)ULONGLONG_MAX ||
(e->force_abort && !rli->stop_for_until))
return;
rli= qev->rgi->rli;
mysql_mutex_lock(&rli->data_lock);
cmp= strcmp(rli->group_relay_log_name, qev->event_relay_log_name);
if (cmp < 0)
{
rli->group_relay_log_pos= qev->future_event_relay_log_pos;
strmake_buf(rli->group_relay_log_name, qev->event_relay_log_name);
rli->notify_group_relay_log_name_update();
} else if (cmp == 0 &&
rli->group_relay_log_pos < qev->future_event_relay_log_pos)
rli->group_relay_log_pos= qev->future_event_relay_log_pos;