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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
40 lines
1.6 KiB
Text
40 lines
1.6 KiB
Text
CREATE TABLE t (a int PRIMARY KEY, b int NOT NULL UNIQUE) engine = InnoDB, STATS_PERSISTENT=0;
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InnoDB 0 transactions not purged
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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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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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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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INSERT INTO t VALUES(10, 20) # trx_2;
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connect con_del_2,localhost,root,,;
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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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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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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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connection con_ins_1;
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connection default;
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INSERT INTO t VALUES(30, 20);
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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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