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14685b10df
The motivation of introducing the parameter innodb_purge_rseg_truncate_frequency in mysql/mysql-server@28bbd66ea5 and mysql/mysql-server@8fc2120fed seems to have been to avoid stalls due to freeing undo log pages or truncating undo log tablespaces. In MariaDB Server, innodb_undo_log_truncate=ON should be a much lighter operation than in MySQL, because it will not involve any log checkpoint. Another source of performance stalls should be trx_purge_truncate_rseg_history(), which is shrinking the history list by freeing the undo log pages whose undo records have been purged. To alleviate that, we will introduce a purge_truncation_task that will offload this from the purge_coordinator_task. In that way, the next innodb_purge_batch_size pages may be parsed and purged while the pages from the previous batch are being freed and the history list being shrunk. The processing of innodb_undo_log_truncate=ON will still remain the responsibility of the purge_coordinator_task. purge_coordinator_state::count: Remove. We will ignore innodb_purge_rseg_truncate_frequency, and act as if it had been set to 1 (the maximum shrinking frequency). purge_coordinator_state::do_purge(): Invoke an asynchronous task purge_truncation_callback() to free the undo log pages. purge_sys_t::iterator::free_history(): Free those undo log pages that have been processed. This used to be a part of trx_purge_truncate_history(). purge_sys_t::clone_end_view(): Take a new value of purge_sys.head as a parameter, so that it will be updated while holding exclusive purge_sys.latch. This is needed for race-free access to the field in purge_truncation_callback(). Reviewed by: Vladislav Lesin
87 lines
3.7 KiB
Text
87 lines
3.7 KiB
Text
--source include/have_innodb.inc
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--source include/count_sessions.inc
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source include/have_debug.inc;
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source include/have_debug_sync.inc;
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CREATE TABLE t (a int PRIMARY KEY, b int NOT NULL UNIQUE) engine = InnoDB, STATS_PERSISTENT=0;
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--source include/wait_all_purged.inc
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--connect(prevent_purge,localhost,root,,)
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start transaction with consistent snapshot;
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--connect(con_del_1,localhost,root,,)
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INSERT INTO t VALUES (20,20);
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SET DEBUG_SYNC = 'innodb_row_search_for_mysql_exit SIGNAL first_del_row_search_mvcc_finished WAIT_FOR first_del_cont';
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--send DELETE FROM t WHERE b = 20 # trx_1
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--connect(con_ins_1,localhost,root,,)
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SET DEBUG_SYNC = 'now WAIT_FOR first_del_row_search_mvcc_finished';
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# It's supposed the following INSERT will be suspended just after
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# lock_wait_start syncpoint, and will be awaken
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# after trx_1 DELETE commits. ib_after_row_insert will be executed
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# after the trx_2 INSERT is woken up. The trx_1 DELETE will wait for
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# first_del_cont signal before commit, and this signal will be sent later.
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# So it's safe to use two signals in a row here, it's guaranted the first
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# signal will be received before the second signal is sent.
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SET DEBUG_SYNC = 'lock_wait_start SIGNAL first_ins_locked';
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SET DEBUG_SYNC = 'ib_after_row_insert SIGNAL first_ins_row_inserted WAIT_FOR first_ins_cont';
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--send INSERT INTO t VALUES(10, 20) # trx_2
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--connect(con_del_2,localhost,root,,)
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# After MDEV-30225 is fixed, the following DELETE creates next-key lock for
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# unqique search for RR, and the above INSERT kills it as deadlock victim.
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# But it still requests not-gap lock for RC.
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SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
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SET DEBUG_SYNC = 'now WAIT_FOR first_ins_locked';
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SET DEBUG_SYNC = 'lock_wait_start SIGNAL second_del_locked';
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##############################################################################
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# trx_3 DELETE is locked by trx_1 DELETE, after trx_1 DELETE is
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# committed, it will still be locked by trx_2 INSERT on delete-marked
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# heap_no 2 record. After trx_2 INSERT inserted the record with heap_no 3,
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# and after heap_no 2 record is purged, trx_3 DELETE will be unlocked and
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# must restore persistent cursor position at heap_no 3 record, as it has the
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# same secondary key value as former heap_no 2 record. Then it must be blocked
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# by trx_2 INSERT, and after trx_2 INSERT is committed, it must
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# delete the record, inserted by trx_2 INSERT, and trx_4 INSERT(see
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# below) must be finished without error. But instead this DELETE restores
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# persistent cursor position to supremum, as a result, it does not delete the
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# record, inserted by trx_2 INSERT, and trx_4 INSERT is finished with
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# duplicate key check error.
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###############################################################################
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--send DELETE FROM t WHERE b = 20 # trx_3
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--connection default
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SET DEBUG_SYNC = 'now WAIT_FOR second_del_locked';
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SET @saved_dbug = @@GLOBAL.debug_dbug;
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SET @@GLOBAL.debug_dbug="d,enable_row_purge_del_mark_exit_sync_point";
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SET DEBUG_SYNC = 'now SIGNAL first_del_cont';
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SET DEBUG_SYNC = 'now WAIT_FOR first_ins_row_inserted';
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--connection con_del_1
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--reap
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--connection default
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--disconnect prevent_purge
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SET DEBUG_SYNC = 'now WAIT_FOR row_purge_del_mark_finished';
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SET @@GLOBAL.debug_dbug = @saved_dbug;
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SET DEBUG_SYNC = 'now SIGNAL first_ins_cont';
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--connection con_del_2
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--reap
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--connection con_ins_1
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--reap
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--connection default
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###############################################################################
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# Duplicate key error is expected if the bug is not fixed.
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###############################################################################
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INSERT INTO t VALUES(30, 20); # trx_4
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--disconnect con_ins_1
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--disconnect con_del_1
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--disconnect con_del_2
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--connection default
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SET DEBUG_SYNC = 'RESET';
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DROP TABLE t;
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--source include/wait_until_count_sessions.inc
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