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