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ba02550166
Problem is that FLUSH TABLES WITH READ LOCK first blocks threads from starting new commits, then waits for running commits to complete. But in-order parallel replication needs commits to happen in a particular order, so this can easily deadlock. To fix this problem, this patch introduces a way to temporarily pause the parallel replication worker threads. Before starting FTWRL, we let all worker threads complete in-progress transactions, and then wait. Then we proceed to take the global read lock. Once the lock is obtained, we unpause the worker threads. Now commits are blocked from starting by the global read lock, so the deadlock will no longer occur.
126 lines
3.1 KiB
Text
126 lines
3.1 KiB
Text
include/rpl_init.inc [topology=1->2]
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*** MDEV-5509: Incorrect value for Seconds_Behind_Master if parallel replication ***
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SET @old_parallel_threads=@@GLOBAL.slave_parallel_threads;
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include/stop_slave.inc
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SET GLOBAL slave_parallel_threads=5;
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include/start_slave.inc
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CREATE TABLE t1 (a INT PRIMARY KEY, b INT);
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CALL mtr.add_suppression("Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. Statement is unsafe because it uses a system function that may return a different value on the slave");
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INSERT INTO t1 VALUES (1,sleep(2));
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Warnings:
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Note 1592 Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. Statement is unsafe because it uses a system function that may return a different value on the slave.
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include/wait_for_slave_param.inc [Seconds_Behind_Master]
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Seconds_Behind_Master should be zero here because the slave is fully caught up and idle.
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Seconds_Behind_Master = '0'
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*** MDEV-8294: Inconsistent behavior of slave parallel threads at runtime ***
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INSERT INTO t1 VALUES (10,0);
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SET sql_log_bin= 0;
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DELETE FROM t1 WHERE a=10;
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SET sql_log_bin= 1;
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INSERT INTO t1 VALUES (10,0);
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SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
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a b
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10 0
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include/wait_for_slave_sql_error.inc [errno=1062]
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SET GLOBAL slave_parallel_threads=8;
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STOP SLAVE;
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SET GLOBAL sql_slave_skip_counter= 1;
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include/start_slave.inc
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SELECT * FROM t1 WHERE a >= 10 ORDER BY a;
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a b
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10 0
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*** MDEV-7818: Deadlock occurring with parallel replication and FTWRL ***
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CREATE TABLE t2 (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
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INSERT INTO t2 VALUES (1,0), (2,0), (3,0);
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include/stop_slave.inc
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SET @old_dbug= @@SESSION.debug_dbug;
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SET @commit_id= 4242;
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SET SESSION debug_dbug="+d,binlog_force_commit_id";
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BEGIN;
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UPDATE t2 SET b=b+1 WHERE a=2;
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COMMIT;
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BEGIN;
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INSERT INTO t2 VALUES (4,10);
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COMMIT;
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SET SESSION debug_dbug= @old_dbug;
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INSERT INTO t2 VALUES (5,0);
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INSERT INTO t2 VALUES (6,0);
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INSERT INTO t2 VALUES (7,0);
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INSERT INTO t2 VALUES (8,0);
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INSERT INTO t2 VALUES (9,0);
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INSERT INTO t2 VALUES (10,0);
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INSERT INTO t2 VALUES (11,0);
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INSERT INTO t2 VALUES (12,0);
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INSERT INTO t2 VALUES (13,0);
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INSERT INTO t2 VALUES (14,0);
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INSERT INTO t2 VALUES (15,0);
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INSERT INTO t2 VALUES (16,0);
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INSERT INTO t2 VALUES (17,0);
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INSERT INTO t2 VALUES (18,0);
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INSERT INTO t2 VALUES (19,0);
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BEGIN;
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SELECT * FROM t2 WHERE a=2 FOR UPDATE;
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a b
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2 0
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include/start_slave.inc
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FLUSH TABLES WITH READ LOCK;
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COMMIT;
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STOP SLAVE;
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SELECT * FROM t2 ORDER BY a;
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a b
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1 0
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2 1
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3 0
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4 10
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5 0
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6 0
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7 0
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8 0
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9 0
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10 0
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11 0
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12 0
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13 0
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14 0
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15 0
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16 0
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17 0
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18 0
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19 0
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UNLOCK TABLES;
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include/wait_for_slave_to_stop.inc
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include/start_slave.inc
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SELECT * FROM t2 ORDER BY a;
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a b
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1 0
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2 1
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3 0
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4 10
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5 0
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6 0
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7 0
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8 0
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9 0
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10 0
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11 0
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12 0
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13 0
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14 0
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15 0
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16 0
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17 0
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18 0
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19 0
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*** MDEV-8318: Assertion `!pool->busy' failed in pool_mark_busy(rpl_parallel_thread_pool*) on concurrent FTWRL ***
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LOCK TABLE t2 WRITE;
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FLUSH TABLES WITH READ LOCK;
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FLUSH TABLES WITH READ LOCK;
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KILL QUERY CID;
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ERROR 70100: Query execution was interrupted
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UNLOCK TABLES;
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UNLOCK TABLES;
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include/stop_slave.inc
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SET GLOBAL slave_parallel_threads=@old_parallel_threads;
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include/start_slave.inc
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DROP TABLE t1, t2;
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include/rpl_end.inc
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