mariadb/mysql-test/main/lock_multi_bug38499.result
Sergei Golubchik bead24b7f3 mariadb-test: wait on disconnect
Remove one of the major sources of race condiitons in mariadb-test.
Normally, mariadb_close() sends COM_QUIT to the server and immediately
disconnects. In mariadb-test it means the test can switch to another
connection and sends queries to the server before the server even
started parsing the COM_QUIT packet and these queries can see the
connection as fully active, as it didn't reach dispatch_command yet.

This is a major source of instability in tests and many - but not all,
still less than a half - tests employ workarounds. The correct one
is a pair count_sessions.inc/wait_until_count_sessions.inc.
Also very popular was wait_until_disconnected.inc, which was completely
useless, because it verifies that the connection is closed, and after
disconnect it always is, it didn't verify whether the server processed
COM_QUIT. Sadly the placebo was as widely used as the real thing.

Let's fix this by making mariadb-test `disconnect` command _to wait_ for
the server to confirm. This makes almost all workarounds redundant.

In some cases count_sessions.inc/wait_until_count_sessions.inc is still
needed, though, as only `disconnect` command is changed:

 * after external tools, like `exec $MYSQL`
 * after failed `connect` command
 * replication, after `STOP SLAVE`
 * Federated/CONNECT/SPIDER/etc after `DROP TABLE`

and also in some XA tests, because an XA transaction is dissociated from
the THD very late, after the server has closed the client connection.

Collateral cleanups: fix comments, remove some redundant statements:
 * DROP IF EXISTS if nothing is known to exist
 * DROP table/view before DROP DATABASE
 * REVOKE privileges before DROP USER
 etc
2025-07-16 09:14:33 +07:00

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SET @odl_sync_frm = @@global.sync_frm;
SET @@global.sync_frm = OFF;
connect locker,localhost,root,,;
connect writer,localhost,root,,;
connection default;
CREATE TABLE t1( a INT, b INT );
CREATE TABLE t2( a INT, b INT );
INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4);
INSERT INTO t2 VALUES (1, 1), (2, 2), (3, 3), (4, 4);
# 1. test regular tables
# 1.1. test altering of columns that multiupdate doesn't use
# 1.1.1. normal mode
# 1.1.2. PS mode
# 1.2. test altering of columns that multiupdate uses
# 1.2.1. normal mode
connection default;
# 1.2.2. PS mode
connection default;
ALTER TABLE t1 ADD COLUMN a INT, LOCK=SHARED;
# 2. test UNIONs
# 2.1. test altering of columns that multiupdate doesn't use
# 2.1.1. normal mode
# 2.1.2. PS mode
# 2.2. test altering of columns that multiupdate uses
# 2.2.1. normal mode
connection default;
# 2.2.2. PS mode
connection default;
DROP TABLE t1,t2;
disconnect locker;
disconnect writer;
SET @@global.sync_frm = @odl_sync_frm;
# End of 5.0 tests