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Problem: ======== During mysqld initialization, if the number of GTIDs added since that last purge of the mysql.gtid_slave_pos tables is greater than or equal to the –-gtid-cleanup-batch-size value, a race condition can occur. Specifically, the binlog background thread will submit the bg_gtid_delete_pending job to the mysql handle manager; however, the mysql handle manager may not be initialized, leading to crashes. Solution: ======== Force the mysql handle manager to initialize/start before the binlog background thread is created. Reviewed By: ============ Andrei Elkin <andrei.elkin@mariadb.com>
68 lines
2.5 KiB
Plaintext
68 lines
2.5 KiB
Plaintext
#
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# Purpose:
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# This test ensures that, during mysqld initialization, the mysql handle
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# manager starts before the binlog background thread. This is because the
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# binlog background thread uses the mysql handle manager, and if the background
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# thread tries to submit a job to the handle manager before it is
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# initialized/started, mysqld can crash (the actual behavior is undefined).
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# This race condition lead to the problem described in MDEV-26473.
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#
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# Methodology:
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# This test ensures that the binlog background thread cannot be started
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# before the mysql manager is started. Specifically, it forces a path in
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# the binlog background thread to call mysql_manager_submit() by reducing
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# --gtid-cleanup-batch-size to be 1 (which submits a job to delete unused rows
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# from the mysql.gtid_slave_pos* tables). With this path forced, the main
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# mysqld thread is suspended just before its handle manager initialization to
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# allow time for the binlog thread to call mysql_manager_submit. The fix
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# associated with this test should enforce that the binlog background thread is
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# not created before the handle manager is initialized.
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#
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# References:
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# MDEV-26473 mysqld got exception 0xc0000005 (rpl_slave_state/rpl_load_gtid_slave_state)
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#
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--source include/have_debug.inc
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--source include/master-slave.inc
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# The race condition discovered from MDEV-26473 is binlog format independent.
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# We use ROW format though because it was used by the reporter.
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--source include/have_binlog_format_row.inc
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--connection master
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--echo # Create a GTID event so the binlog background thread will submit a
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--echo # mysql handler job the next time mysqld is restarted.
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create table t1 (a int);
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--source include/save_master_gtid.inc
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--connection slave
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--source include/sync_with_master_gtid.inc
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--echo # Set a debug point that forces the main mysqld thread to sleep before
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--echo # anything is initialized for the mysql handle manager
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--let $rpl_server_parameters=--debug_dbug="+d,delay_start_handle_manager"
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--echo # Restart the slave mysqld instance so it re-initializes with the
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--echo # binlog background thread submitting a mysql handler job and the
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--echo # mysql handler initialization suspending for a second. Without the fix
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--echo # associated with this test/patch, the following restart will error
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--echo # with a failed assertion.
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--source include/rpl_restart_server.inc
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--source include/start_slave.inc
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--echo #
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--echo # Cleanup
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--echo #
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--connection master
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drop table t1;
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--source include/save_master_gtid.inc
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--connection slave
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--source include/sync_with_master_gtid.inc
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--source include/rpl_end.inc
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