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MDEV-29621: Replica stopped by locks on sequence

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When using binlog_row_image=FULL with sequence table inserts, a
replica can deadlock because it treats full inserts in a sequence as DDL
statements by getting an exclusive lock on the sequence table. It
has been observed that with parallel replication, this exclusive
lock on the sequence table can lead to a deadlock where one
transaction has the exclusive lock and is waiting on a prior
transaction to commit, whereas this prior transaction is waiting on
the MDL lock.

This fix for this is on the master side, to raise FL_DDL
flag on the GTID of a full binlog_row_image write of a sequence table.
This forces the slave to execute the statement serially so a deadlock
cannot happen.

A test verifies the deadlock also to prove it happen on the OLD (pre-fixes)
slave.

OLD (buggy master) -replication-> NEW (fixed slave) is provided.
As the pre-fixes master's full row-image may represent both
SELECT NEXT VALUE and INSERT, the parallel slave pessimistically
waits for the prior transaction to have committed before to take on the
critical part of the second (like INSERT in the test) event execution.
The waiting exploits a parallel slave's retry mechanism which is
controlled by `@@global.slave_transaction_retries`.

Note that in order to avoid any persistent 'Deadlock found' 2013 error
in OLD -> NEW, `slave_transaction_retries` may need to be set to a
higher than the default value.
START-SLAVE is an effective work-around if this still happens.
This commit is contained in:
Andrei 2023-03-18 21:11:07 +02:00
commit 55a53949be
8 changed files with 190 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

3
sql/ha_sequence.cc
View file

@ -235,8 +235,9 @@ int ha_sequence::write_row(uchar *buf)
on master and slaves
- Check that the new row is an accurate SEQUENCE object
*/
THD *thd= table->in_use;
/* mark a full binlog image insert to force non-parallel slave */
thd->transaction.stmt.mark_trans_did_ddl();
if (table->s->tmp_table == NO_TMP_TABLE &&
thd->mdl_context.upgrade_shared_lock(table->mdl_ticket,
MDL_EXCLUSIVE,

27
sql/log_event.cc
View file

@ -13713,8 +13713,14 @@ Rows_log_event::write_row(rpl_group_info *rgi,
int Rows_log_event::update_sequence()
{
TABLE *table= m_table; // pointer to event's table
bool old_master= false;
int err= 0;
if (!bitmap_is_set(table->rpl_write_set, MIN_VALUE_FIELD_NO))
if (!bitmap_is_set(table->rpl_write_set, MIN_VALUE_FIELD_NO) ||
(!(table->in_use->rgi_slave->gtid_ev_flags2 & Gtid_log_event::FL_DDL) &&
!(old_master=
rpl_master_has_bug(thd->rgi_slave->rli,
29621, FALSE, FALSE, FALSE, TRUE))))
{
/* This event come from a setval function executed on the master.
Update the sequence next_number and round, like we do with setval()
@ -13727,12 +13733,27 @@ int Rows_log_event::update_sequence()
return table->s->sequence->set_value(table, nextval, round, 0) > 0;
}
if (thd->rgi_slave->is_parallel_exec && old_master)
{
DBUG_ASSERT(thd->rgi_slave->parallel_entry);
/*
With parallel replication enabled, we can't execute alongside any other
transaction in which we may depend, so we force retry to release
the server layer table lock for possible prior in binlog order
same table transactions.
*/
if (thd->rgi_slave->parallel_entry->last_committed_sub_id <
thd->rgi_slave->wait_commit_sub_id)
{
err= ER_LOCK_DEADLOCK;
my_error(err, MYF(0));
}
}
/*
Update all fields in table and update the active sequence, like with
ALTER SEQUENCE
*/
return table->file->ha_write_row(table->record[0]);
return err == 0 ? table->file->ha_write_row(table->record[0]) : err;
}

7
sql/rpl_parallel.cc
View file

@ -2780,7 +2780,12 @@ rpl_parallel::do_event(rpl_group_info *serial_rgi, Log_event *ev,
if (mode <= SLAVE_PARALLEL_MINIMAL ||
!(gtid_flags & Gtid_log_event::FL_GROUP_COMMIT_ID) ||
e->last_commit_id != gtid_ev->commit_id)
e->last_commit_id != gtid_ev->commit_id ||
/*
MULTI_BATCH is also set when the current gtid even being a member
of a commit group is flagged as DDL which disallows parallel.
*/
(gtid_flags & Gtid_log_event::FL_DDL))
flags|= group_commit_orderer::MULTI_BATCH;
/* Make sure we do not attempt to run DDL in parallel speculatively. */
if (gtid_flags & Gtid_log_event::FL_DDL)

36
sql/slave.cc
View file

@ -8028,14 +8028,15 @@ end:
@return TRUE if master has the bug, FALSE if it does not.
*/
bool rpl_master_has_bug(const Relay_log_info *rli, uint bug_id, bool report,
bool (*pred)(const void *), const void *param)
bool (*pred)(const void *), const void *param,
bool maria_master)
{
struct st_version_range_for_one_bug {
uint bug_id;
const uchar introduced_in[3]; // first version with bug
const uchar fixed_in[3]; // first version with fix
};
static struct st_version_range_for_one_bug versions_for_all_bugs[]=
static struct st_version_range_for_one_bug versions_for_their_bugs[]=
{
{24432, { 5, 0, 24 }, { 5, 0, 38 } },
{24432, { 5, 1, 12 }, { 5, 1, 17 } },
@ -8043,13 +8044,30 @@ bool rpl_master_has_bug(const Relay_log_info *rli, uint bug_id, bool report,
{33029, { 5, 1, 0 }, { 5, 1, 12 } },
{37426, { 5, 1, 0 }, { 5, 1, 26 } },
};
static struct st_version_range_for_one_bug versions_for_our_bugs[]=
{
{29621, { 10, 3, 36 }, { 10, 3, 39 } },
{29621, { 10, 4, 26 }, { 10, 4, 29 } },
{29621, { 10, 5, 17 }, { 10, 5, 20 } },
{29621, { 10, 6, 9 }, { 10, 6, 13 } },
{29621, { 10, 7, 5 }, { 10, 7, 9 } },
{29621, { 10, 8, 4 }, { 10, 8, 8 } },
{29621, { 10, 9, 2 }, { 10, 9, 6 } },
{29621, { 10, 10,1 }, { 10, 10,4 } },
{29621, { 10, 11,1 }, { 10, 11,3 } },
};
const uchar *master_ver=
rli->relay_log.description_event_for_exec->server_version_split.ver;
DBUG_ASSERT(sizeof(rli->relay_log.description_event_for_exec->server_version_split.ver) == 3);
for (uint i= 0;
i < sizeof(versions_for_all_bugs)/sizeof(*versions_for_all_bugs);i++)
struct st_version_range_for_one_bug* versions_for_all_bugs= maria_master ?
versions_for_our_bugs : versions_for_their_bugs;
uint all_size= maria_master ?
sizeof(versions_for_our_bugs)/sizeof(*versions_for_our_bugs) :
sizeof(versions_for_their_bugs)/sizeof(*versions_for_their_bugs);
for (uint i= 0; i < all_size; i++)
{
const uchar *introduced_in= versions_for_all_bugs[i].introduced_in,
*fixed_in= versions_for_all_bugs[i].fixed_in;
@ -8058,18 +8076,21 @@ bool rpl_master_has_bug(const Relay_log_info *rli, uint bug_id, bool report,
(memcmp(fixed_in, master_ver, 3) > 0) &&
(pred == NULL || (*pred)(param)))
{
const char *bug_source= maria_master ?
"https://jira.mariadb.org/browse/MDEV-" :
"http://bugs.mysql.com/bug.php?id=";
if (!report)
return TRUE;
// a short message for SHOW SLAVE STATUS (message length constraints)
my_printf_error(ER_UNKNOWN_ERROR, "master may suffer from"
" http://bugs.mysql.com/bug.php?id=%u"
" %s%u"
" so slave stops; check error log on slave"
" for more info", MYF(0), bug_id);
" for more info", MYF(0), bug_source, bug_id);
// a verbose message for the error log
rli->report(ERROR_LEVEL, ER_UNKNOWN_ERROR, NULL,
"According to the master's version ('%s'),"
" it is probable that master suffers from this bug:"
" http://bugs.mysql.com/bug.php?id=%u"
" %s%u"
" and thus replicating the current binary log event"
" may make the slave's data become different from the"
" master's data."
@ -8083,6 +8104,7 @@ bool rpl_master_has_bug(const Relay_log_info *rli, uint bug_id, bool report,
" equal to '%d.%d.%d'. Then replication can be"
" restarted.",
rli->relay_log.description_event_for_exec->server_version,
bug_source,
bug_id,
fixed_in[0], fixed_in[1], fixed_in[2]);
return TRUE;

3
sql/slave.h
View file

@ -231,7 +231,8 @@ bool show_all_master_info(THD* thd);
void show_binlog_info_get_fields(THD *thd, List<Item> *field_list);
bool show_binlog_info(THD* thd);
bool rpl_master_has_bug(const Relay_log_info *rli, uint bug_id, bool report,
bool (*pred)(const void *), const void *param);
bool (*pred)(const void *), const void *param,
bool maria_master= false);
bool rpl_master_erroneous_autoinc(THD* thd);
const char *print_slave_db_safe(const char *db);