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Code Activity

MDEV-17515: GTID Replication in optimistic mode deadlock

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Problem:
=======
In slave_parallel_mode=optimistic configuration, when admin commands and
DML operation on the same table are scheduled simultaneously for execution,
it results in lock conflict and slave server either hangs due to
deadlock or goes down with an assert.

Analysis:
========
Admin commands OPTIMIZE, REPAIR and ANALYZE are written to binary log as
ordinary transactions. When 'slave_parallel_mode' is 'optimistic' DMLs are
allowed to run in parallel. But these locks are not detected by parallel
replication deadlock detection-and-handling mechanism. At times they result
in deadlock or assertion.

Fix:
===
Flag admin commands as DDL in Gtid_log_event at the time of writing to
binary log. Add a new bit EXECUTED_TABLE_ADMIN_CMD to
'm_unsafe_rollback_flags'. During 'mysql_admin_table' command execution it
accepts a list of tables to be processed and executes them in a loop. Upon
successful execution enable 'EXECUTED_TABLE_ADMIN_CMD' bit in
thd->transaction.stmt_unsafe_rollback_flags. Gtid_log_event constructor
will notice this flag and mark the current transaction with 'FL_DDL' flag.
Gtid_log_events marked as FL_DDL will not be scheduled parallel execution,
on the slave. They will execute in isolation to prevent deadlocks.

Note: Removed the call to 'trans_commit_implicit' from 'mysql_admin_table'
function as 'mysql_execute_command' will take care of invoking
'trans_commit_implicit'.
This commit is contained in:
Sujatha
2021-05-12 18:00:06 +05:30
parent 80ae3677e1
commit 410e3c1a9a
8 changed files with 257 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

77
mysql-test/suite/rpl/r/rpl_mark_optimize_tbl_ddl.result Normal file
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include/rpl_init.inc [topology=1->2]
connection server_1;
FLUSH TABLES;
ALTER TABLE mysql.gtid_slave_pos ENGINE=InnoDB;
connection server_2;
SET @save_slave_parallel_threads= @@GLOBAL.slave_parallel_threads;
SET @save_slave_parallel_mode= @@GLOBAL.slave_parallel_mode;
include/stop_slave.inc
SET GLOBAL slave_parallel_threads=2;
SET GLOBAL slave_parallel_mode=optimistic;
include/start_slave.inc
connection server_1;
CREATE TABLE t1(a INT) ENGINE=INNODB;
OPTIMIZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 optimize note Table does not support optimize, doing recreate + analyze instead
test.t1 optimize status OK
INSERT INTO t1 VALUES(1);
INSERT INTO t1 SELECT 1+a FROM t1;
INSERT INTO t1 SELECT 2+a FROM t1;
connection server_2;
#
# Verify that following admin commands are marked as ddl
# 'OPTIMIZE TABLE', 'REPAIR TABLE' and 'ANALYZE TABLE'
#
connection server_1;
OPTIMIZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 optimize note Table does not support optimize, doing recreate + analyze instead
test.t1 optimize status OK
REPAIR TABLE t1;
Table Op Msg_type Msg_text
test.t1 repair note The storage engine for the table doesn't support repair
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
FLUSH LOGS;
FOUND 1 /GTID 0-1-8 ddl/ in mysqlbinlog.out
FOUND 1 /GTID 0-1-9 ddl/ in mysqlbinlog.out
FOUND 1 /GTID 0-1-10 ddl/ in mysqlbinlog.out
#
# Clean up
#
DROP TABLE t1;
connection server_2;
FLUSH LOGS;
#
# Check that ALTER TABLE commands with ANALYZE, OPTIMIZE and REPAIR on
# partitions will be marked as DDL in binary log.
#
connection server_1;
CREATE TABLE t1(id INT) PARTITION BY RANGE (id) (PARTITION p0 VALUES LESS THAN (100),
PARTITION pmax VALUES LESS THAN (MAXVALUE));
INSERT INTO t1 VALUES (1), (10), (100), (1000);
ALTER TABLE t1 ANALYZE PARTITION p0;
Table Op Msg_type Msg_text
test.t1 analyze status OK
ALTER TABLE t1 OPTIMIZE PARTITION p0;
Table Op Msg_type Msg_text
test.t1 optimize status OK
ALTER TABLE t1 REPAIR PARTITION p0;
Table Op Msg_type Msg_text
test.t1 repair status OK
FLUSH LOGS;
FOUND 1 /GTID 0-1-14 ddl/ in mysqlbinlog.out
FOUND 1 /GTID 0-1-15 ddl/ in mysqlbinlog.out
FOUND 1 /GTID 0-1-16 ddl/ in mysqlbinlog.out
#
# Clean up
#
DROP TABLE t1;
connection server_2;
include/stop_slave.inc
SET GLOBAL slave_parallel_threads= @save_slave_parallel_threads;
SET GLOBAL slave_parallel_mode= @save_slave_parallel_mode;
include/start_slave.inc
include/rpl_end.inc