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Disallow killing a thread that has started TOI until it completes #488

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c8609ce
MDEV-36116: Remove debug assert in TOI when executing thread is killed
denis-protivensky Feb 18, 2025
df9c6d7
Disallow killing a thread that has started TOI until it completes
denis-protivensky Feb 26, 2025
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22 changes: 22 additions & 0 deletions mysql-test/suite/galera/r/MDEV-36116.result
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@@ -0,0 +1,22 @@
connection node_2;
connection node_1;
connect con1,127.0.0.1,root,,test,$NODE_MYPORT_1;
connection node_1;
CALL mtr.add_suppression("CREATE TABLE isolation failure");
SET DEBUG_SYNC = 'wsrep_kill_thd_before_enter_toi SIGNAL may_kill WAIT_FOR continue';
CREATE TABLE t1 (a INT) ENGINE=InnoDB;
connection con1;
SET DEBUG_SYNC = 'now WAIT_FOR may_kill';
SET DEBUG_SYNC = 'now SIGNAL continue';
connection node_1;
ERROR HY000: Lost connection to MySQL server during query
connection node_2;
SHOW TABLES LIKE 't1';
Tables_in_test (t1)
connection con1;
SHOW TABLES LIKE 't1';
Tables_in_test (t1)
SET DEBUG_SYNC = 'RESET';
disconnect con1;
disconnect node_2;
disconnect node_1;
42 changes: 42 additions & 0 deletions mysql-test/suite/galera/t/MDEV-36116.test
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@@ -0,0 +1,42 @@
#
# MDEV-36116: TOI crashes in debug assert if executing thread is killed.
#

--source include/galera_cluster.inc
--source include/have_debug_sync.inc
--source include/have_debug.inc

--connect con1,127.0.0.1,root,,test,$NODE_MYPORT_1

# Start TOI operation and wait for the thread to be killed.
--connection node_1
CALL mtr.add_suppression("CREATE TABLE isolation failure");

--let $connection_id = `SELECT CONNECTION_ID()`
SET DEBUG_SYNC = 'wsrep_kill_thd_before_enter_toi SIGNAL may_kill WAIT_FOR continue';
--send
CREATE TABLE t1 (a INT) ENGINE=InnoDB;

# Kill the thread and let it continue.
--connection con1
SET DEBUG_SYNC = 'now WAIT_FOR may_kill';
--disable_query_log
--eval KILL CONNECTION $connection_id
--enable_query_log
SET DEBUG_SYNC = 'now SIGNAL continue';

--connection node_1
--error 2013
--reap

# Verify no tables created on either nodes.
--connection node_2
SHOW TABLES LIKE 't1';

--connection con1
SHOW TABLES LIKE 't1';

# Cleanup
SET DEBUG_SYNC = 'RESET';
--disconnect con1
--source include/galera_end.inc
19 changes: 17 additions & 2 deletions sql/wsrep_mysqld.cc
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Expand Up @@ -2621,12 +2621,13 @@ int wsrep_to_isolation_begin(THD *thd, const char *db_, const char *table_,
const wsrep::key_array *fk_tables,
const HA_CREATE_INFO *create_info)
{
DEBUG_SYNC(thd, "wsrep_kill_thd_before_enter_toi");
mysql_mutex_lock(&thd->LOCK_thd_kill);
const killed_state killed = thd->killed;
mysql_mutex_unlock(&thd->LOCK_thd_kill);
if (killed)
{
DBUG_ASSERT(FALSE);
/* The thread may have been killed as a result of memory pressure. */
return -1;
}

Expand Down Expand Up @@ -2698,6 +2699,10 @@ int wsrep_to_isolation_begin(THD *thd, const char *db_, const char *table_,

if (thd->variables.wsrep_on && wsrep_thd_is_local(thd))
{
mysql_mutex_lock(&thd->LOCK_thd_kill);
if (thd->killed) wsrep_backup_kill_for_commit(thd);
mysql_mutex_unlock(&thd->LOCK_thd_kill);

switch (wsrep_OSU_method_get(thd)) {
case WSREP_OSU_TOI:
ret= wsrep_TOI_begin(thd, db_, table_, table_list, alter_info, fk_tables,
Expand Down Expand Up @@ -2728,9 +2733,12 @@ int wsrep_to_isolation_begin(THD *thd, const char *db_, const char *table_,
case 1:
/* TOI replication skipped, treat as success */
ret= 0;
break;
/* fall through */
case -1:
/* TOI replication failed, treat as error */
mysql_mutex_lock(&thd->LOCK_thd_kill);
wsrep_restore_kill_after_commit(thd);
mysql_mutex_unlock(&thd->LOCK_thd_kill);
break;
}
}
Expand Down Expand Up @@ -2759,6 +2767,13 @@ void wsrep_to_isolation_end(THD *thd)
DBUG_ASSERT(0);
}
if (wsrep_emulate_bin_log) wsrep_thd_binlog_trx_reset(thd);

mysql_mutex_lock(&thd->LOCK_thd_kill);
if (thd->wsrep_abort_by_kill != NOT_KILLED)
{
wsrep_restore_kill_after_commit(thd);
}
mysql_mutex_unlock(&thd->LOCK_thd_kill);
}

#define WSREP_MDL_LOG(severity, msg, schema, schema_len, req, gra) \
Expand Down
1 change: 0 additions & 1 deletion sql/wsrep_thd.cc
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Expand Up @@ -496,7 +496,6 @@ void wsrep_backup_kill_for_commit(THD *thd)

void wsrep_restore_kill_after_commit(THD *thd)
{
DBUG_ASSERT(wsrep_is_active(thd));
mysql_mutex_assert_owner(&thd->LOCK_thd_kill);
thd->killed= thd->wsrep_abort_by_kill;
my_free(thd->killed_err);
Expand Down