# # 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. # # Addendum 1) This test is extended for MDEV-33799, as the original fix # left out the possibility that the binlog background thread can be # started during recovery if the binary log is used as the transaction # coordinator. This resulted in similar segfaults as seen by MDEV-26473. # # References: # MDEV-26473 mysqld got exception 0xc0000005 (rpl_slave_state/rpl_load_gtid_slave_state) # MDEV-33799 mysql_manager_submit Segfault at Startup Still Possible During Recovery # --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 # MDEV-33799 --echo # Ensure that when the binary log is used for recovery (as tc log), that --echo # the recovery process cannot start the binlog background thread before --echo # the mysql handle manager has started. --connection slave --echo # Add test suppresssions so crash recovery messages don't fail the test set session sql_log_bin=0; call mtr.add_suppression("mariadbd: Got error '145.*"); call mtr.add_suppression("Checking table:.*"); call mtr.add_suppression("mysql.gtid_slave_pos:.*hasn't closed the table properly"); call mtr.add_suppression("Can't init tc log"); call mtr.add_suppression("Aborting"); set session sql_log_bin=1; --echo # Create slave-side only table create table t2 (a int) engine=innodb; --write_file $MYSQLTEST_VARDIR/tmp/mysqld.2.expect wait EOF --echo # Crash mariadbd when binlogging transaction to corrupt database state --connection slave1 set @@session.debug_dbug="+d,crash_before_writing_xid"; --send insert into t2 values (1) --connection slave --source include/wait_until_disconnected.inc --connection slave1 --error 2013,ER_CONNECTION_KILLED --reap --echo # Restart mariadbd in recovery mode. Note --tc-heuristic-recover --echo # forces mysqld to exit with error, so we run mariadbd via CLI --echo # MYSQLD_LAST_CMD --debug_dbug="+d,delay_start_handle_manager" --tc-heuristic-recover=COMMIT --error 1 --exec $MYSQLD_LAST_CMD --debug_dbug="+d,delay_start_handle_manager" --tc-heuristic-recover=COMMIT --append_file $MYSQLTEST_VARDIR/tmp/mysqld.2.expect restart EOF --connection server_2 --enable_reconnect --source include/wait_until_connected_again.inc --connection slave1 --enable_reconnect --source include/wait_until_connected_again.inc --connection slave --enable_reconnect --source include/wait_until_connected_again.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 drop table t2; --source include/rpl_end.inc