mariadb/mysql-test/suite/rpl/t/rpl_parallel2.test
unknown 8cc6e90d74 MDEV-5509: Seconds_behind_master incorrect in parallel replication
The problem was a race between the SQL driver thread and the worker threads.
The SQL driver thread would set rli->last_master_timestamp to zero to
mark that it has caught up with the master, while the worker threads would
set it to the timestamp of the executed event. This can happen out-of-order
in parallel replication, causing the "caught up" status to be overwritten
and Seconds_Behind_Master to wrongly grow when the slave is idle.

To fix, introduce a separate flag rli->sql_thread_caught_up to mark that the
SQL driver thread is caught up. This avoids issues with worker threads
overwriting the SQL driver thread status. In parallel replication, we then
make SHOW SLAVE STATUS check in addition that all worker threads are idle
before showing Seconds_Behind_Master as 0 due to slave idle.
2014-01-08 11:00:44 +01:00

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--source include/have_binlog_format_statement.inc
--let $rpl_topology=1->2
--source include/rpl_init.inc
--echo *** MDEV-5509: Incorrect value for Seconds_Behind_Master if parallel replication ***
--connection server_2
SET @old_parallel_threads=@@GLOBAL.slave_parallel_threads;
--source include/stop_slave.inc
SET GLOBAL slave_parallel_threads=5;
--source include/start_slave.inc
--connection server_1
CREATE TABLE t1 (a INT PRIMARY KEY, b INT);
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");
--save_master_pos
--connection server_2
--sync_with_master
--connection server_1
INSERT INTO t1 VALUES (1,sleep(2));
--save_master_pos
--connection server_2
--sync_with_master
--echo Seconds_Behind_Master should be zero here because the slave is fully caught up and idle.
--let $status_items= Seconds_Behind_Master
--source include/show_slave_status.inc
--connection server_2
--source include/stop_slave.inc
SET GLOBAL slave_parallel_threads=@old_parallel_threads;
--source include/start_slave.inc
--connection server_1
DROP TABLE t1;
--source include/rpl_end.inc