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bead24b7f3
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
33 lines
901 B
Text
33 lines
901 B
Text
# MDEV-20946 Hard FTWRL deadlock under user level locks
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#
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# Deadlock detector should resolve conflicts between FTWRL and user locks.
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--source include/have_debug_sync.inc
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CREATE TABLE t1(a INT);
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SELECT GET_LOCK("l1", 0);
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connect(con1,localhost,root,,);
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LOCK TABLES t1 WRITE;
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connection default;
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set debug_sync='mdl_acquire_lock_wait SIGNAL ftwrl';
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send FLUSH TABLES WITH READ LOCK;
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# At this point "default" is waiting for tables to be unlocked from
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# LOCK TABLES WRITE issued by "con1".
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connection con1;
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set debug_sync='now WAIT_FOR ftwrl';
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# The lock in the following GET_LOCK cannot be acquired since "default" holds
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# a lock on "l1" and is waiting in FLUSH TABLES for con1.
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--error ER_LOCK_DEADLOCK
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SELECT GET_LOCK("l1", 1000);
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disconnect con1; # Performs an implicit UNLOCK TABLES.
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connection default;
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reap;
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SELECT RELEASE_LOCK("l1");
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UNLOCK TABLES;
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DROP TABLE t1;
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set debug_sync='reset';
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