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78a04a4c22
1. The merge aeccbbd926 has overwritten
lock0lock.cc, and the changes of MDEV-29622 and MDEV-29635 were
partially lost, this commit restores the changes.
2. innodb.deadlock_wait_thr_race test:
The following hang was found during testing.
There is deadlock_report_before_lock_releasing sync point in
Deadlock::report(), which is waiting for sel_cont signal under lock_sys_t
lock. The signal must be issued after "UPDATE t SET b = 100" rollback,
and that rollback is executing undo record, which is blocked
on dict_sys latch request. dict_sys is locked by the thread of statistics
update(dict_stats_save()), and during that update lock_sys lock is
requested, and can't be acquired as Deadlock::report() holds it. We have
to disable statistics update to make the test stable.
But even if statistics update is disabled, and transaction with consistent
snapshot is started at the very beginning of the test to prevent purging,
the purge can still be invoked for system tables, and it tries to open
system table by id, what causes dict_sys.freeze() call and dict_sys
latching. What, in combination with lock_sys::xx_lock() causes the same
deadlock as described above. We need to disable purging globally for the
test as well.
All the above is applicable to innodb.deadlock_wait_lock_race test also.
72 lines
3.1 KiB
Plaintext
72 lines
3.1 KiB
Plaintext
--source include/have_innodb.inc
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--source include/have_debug_sync.inc
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--source include/count_sessions.inc
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# Purge can cause deadlock in the test, requesting page's RW_X_LATCH for trx
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# ids reseting, after trx 2 acqured RW_S_LATCH and suspended in debug sync point
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# lock_trx_handle_wait_enter, waiting for upd_cont signal, which must be
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# emitted after the last SELECT in this test. The last SELECT will hang waiting
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# for purge RW_X_LATCH releasing, and trx 2 will be rolled back by timeout.
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# There is deadlock_report_before_lock_releasing sync point in
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# Deadlock::report(), which is waiting for sel_cont signal under
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# lock_sys_t lock. The signal must be issued after "UPDATE t SET b = 100"
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# rollback, and that rollback is executing undo record, which is blocked on
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# dict_sys latch request. dict_sys is locked by the thread of statistics
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# update(dict_stats_save()), and during that update lock_sys lock is requested,
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# and can't be acquired as Deadlock::report() holds it. We have to disable
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# statistics update to make the test stable.
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CREATE TABLE t (a int PRIMARY KEY, b int) engine = InnoDB STATS_PERSISTENT=0;
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CREATE TABLE t2 (a int PRIMARY KEY) engine = InnoDB STATS_PERSISTENT=0;
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INSERT INTO t VALUES (10, 10), (20, 20), (30, 30);
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INSERT INTO t2 VALUES (10), (20), (30);
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BEGIN; # trx 1
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# The following update is necessary to increase the transaction weight, which is
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# calculated as the number of locks + the number of undo records during deadlock
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# report. Victim's transaction should have minimum weight. We need trx 2 to be
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# choosen as victim, that's why we need to increase the current transaction
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# weight.
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UPDATE t2 SET a = a + 100;
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SELECT * FROM t WHERE a = 20 FOR UPDATE;
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--connect(con_2,localhost,root,,)
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# RC is necessary to do semi-consistent read
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SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
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# It will be hit on trying to lock (20,20).
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SET DEBUG_SYNC = 'lock_trx_handle_wait_enter SIGNAL upd_locked WAIT_FOR upd_cont';
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SET DEBUG_SYNC = 'trx_t_release_locks_enter SIGNAL sel_cont WAIT_FOR upd_cont_2';
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BEGIN; # trx 2
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# We must not modify primary key fields to cause rr_sequential() read record
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# function choosing in mysql_update(), i.e. both query_plan.using_filesort and
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# query_plan.using_io_buffer must be false during init_read_record() call.
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# The following UPDATE will be chosen as deadlock victim and rolled back.
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--send UPDATE t SET b = 100
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--connection default
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SET DEBUG_SYNC="now WAIT_FOR upd_locked";
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SET DEBUG_SYNC="deadlock_report_before_lock_releasing SIGNAL upd_cont WAIT_FOR sel_cont";
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SET DEBUG_SYNC="lock_wait_before_suspend SIGNAL sel_before_suspend";
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# If the bug is not fixed, the following SELECT will crash, as the above UPDATE
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# will reset trx->lock.wait_thr during rollback
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--send SELECT * FROM t WHERE a = 10 FOR UPDATE;
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--connect(con_3,localhost,root,,)
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SET DEBUG_SYNC="now WAIT_FOR sel_before_suspend";
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SET DEBUG_SYNC="now SIGNAL upd_cont_2";
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--disconnect con_3
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--connection con_2
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--error ER_LOCK_DEADLOCK
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--reap
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--disconnect con_2
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--connection default
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--reap
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SET DEBUG_SYNC = 'RESET';
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DROP TABLE t;
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DROP TABLE t2;
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--source include/wait_until_count_sessions.inc
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