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Code Activity

MDEV-7237: Parallel replication: incorrect relaylog position after stop/start the slave

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The replication relay log position was sometimes updated incorrectly at the
end of a transaction in parallel replication. This happened because the relay
log file name was taken from the current Relay_log_info (SQL driver thread),
not the correct value for the transaction in question.

The result was that if a transaction was applied while the SQL driver thread
was at least one relay log file ahead, _and_ the SQL thread was subsequently
stopped before applying any events from the most recent relay log file, then
the relay log position would be incorrect - wrong relay log file name. Thus,
when the slave was started again, usually a relay log read error would result,
or in rare cases, if the position happened to be readable, the slave might
even skip arbitrary amounts of events.

In GTID mode, the relay log position is reset when both slave threads are
restarted, so this bug would only be seen in non-GTID mode, or in GTID mode
when only the SQL thread, not the IO thread, was stopped.
This commit is contained in:
Kristian Nielsen
2014-12-01 13:53:57 +01:00
parent f8e1952be4
commit 52b25934d7
4 changed files with 151 additions and 2 deletions
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48
mysql-test/suite/rpl/r/rpl_parallel.result
View File

@@ -972,6 +972,54 @@ SET GLOBAL binlog_format= @old_format;
SET GLOBAL slave_parallel_threads=0;
SET GLOBAL slave_parallel_threads=10;
include/start_slave.inc
*** MDEV-7237: Parallel replication: incorrect relaylog position after stop/start the slave ***
INSERT INTO t2 VALUES (40);
include/stop_slave.inc
CHANGE MASTER TO master_use_gtid=no;
SET @old_dbug= @@GLOBAL.debug_dbug;
SET GLOBAL debug_dbug="+d,rpl_parallel_scheduled_gtid_0_x_100";
SET GLOBAL debug_dbug="+d,rpl_parallel_wait_for_done_trigger";
SET GLOBAL slave_parallel_threads=0;
SET GLOBAL slave_parallel_threads=10;
INSERT INTO t2 VALUES (41);
INSERT INTO t2 VALUES (42);
DELETE FROM t2 WHERE a=40;
INSERT INTO t2 VALUES (43);
INSERT INTO t2 VALUES (44);
FLUSH LOGS;
INSERT INTO t2 VALUES (45);
SET gtid_seq_no=100;
INSERT INTO t2 VALUES (46);
BEGIN;
SELECT * FROM t2 WHERE a=40 FOR UPDATE;
a
40
include/start_slave.inc
SET debug_sync= 'now WAIT_FOR scheduled_gtid_0_x_100';
STOP SLAVE;
SET debug_sync= 'now WAIT_FOR wait_for_done_waiting';
ROLLBACK;
include/wait_for_slave_sql_to_stop.inc
SELECT * FROM t2 WHERE a >= 40 ORDER BY a;
a
41
42
include/start_slave.inc
SELECT * FROM t2 WHERE a >= 40 ORDER BY a;
a
41
42
43
44
45
46
include/stop_slave.inc
SET GLOBAL debug_dbug=@old_dbug;
SET DEBUG_SYNC= 'RESET';
SET GLOBAL slave_parallel_threads=0;
SET GLOBAL slave_parallel_threads=10;
CHANGE MASTER TO master_use_gtid=slave_pos;
include/start_slave.inc
include/stop_slave.inc
SET GLOBAL slave_parallel_threads=@old_parallel_threads;
include/start_slave.inc