Please ignore this outdated comment.

The comment explains how to replay the most probably same problem 

based on the replay test in bs_2.tgz.

bs_2.tgz and the comment could be removed in case it turns out that

ml_31_M.test was sufficient for fixing the problem.

How to replay the problem?

-------------------------------------------

cd <source>/mysql-test

tar xvzf bs_2.tgz

--> mysqltest_background.sh  

      A shellscript for running session 1 and 2 activity in background +

     signaling when failures happened etc.

--> main/bs_2.test

      The MTR test

cd <source with binaries>/mysql-test

./mysql-test-run.pl --mem bs_2.test | tee prt

prt itself tells if the test failed but lacks sometimes important details.

Example:

worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 16000..16019

main.bs_2 'innodb'                       [ fail ]

        Test ended at 2019-02-18 22:12:05

CURRENT_TEST: main.bs_2

mysqltest: At line 124:

The result from queries just before the failure was:

< snip >

   ALTER TABLE t0 DROP KEY `idx1`;

}

--echo # End   of SQL_FILE reached

End   of content of '/home/mleich/Server/10.4/bld_debug/mysql-test/var/tmp/sql.1' ----

Start executing '/home/mleich/Server/10.4/bld_debug/mysql-test/var/tmp/sql.1' at TS: 1550524323

End   executing '/home/mleich/Server/10.4/bld_debug/mysql-test/var/tmp/sql.1' at TS: 1550524323 and status was 1

Begin of       output ----

# Begin of SQL_FILE

SET AUTOCOMMIT = 0 ;

SET SESSION lock_wait_timeout = 2  ;

SET SESSION innodb_lock_wait_timeout = 1 ;

not ok

End   of       output ----

Begin of error output ----

mysqltest: At line 20: command "file_exists" failed with wrong error: 1  my_errno: 2  errno: 2

End   of error output ----

The file '/home/mleich/Server/10.4/bld_debug/mysql-test/var/tmp/run' does no more exist.

This means some concurrent session has observed a problem and deleted that file.

Assuming that this is the reason for my exit status > 0.

ENDE 1550524323

var/log/bs_2.log  is test output with details.

Shortened example:

CREATE TABLE t0 ( col1 INT) ENGINE = MyISAM  ;

# One of the concurrent SQL runner has removed the file '/home/mleich/Server/10.4/bld_debug/mysql-test/var/tmp/run'.

# == Hit an unexpected effect.

MY_CURRENT_TS : 1550524313 , MY_START_TS : 1550524323 , MY_END_TS : 1550524383

...

# Begin of SQL_FILE

SET SESSION wait_timeout = 2147483, max_statement_time = 0;

SET SESSION lock_wait_timeout = 31536000;

not ok

End   of       output ----

Begin of error output ----

mysqltest: At line 30: query 'BACKUP STAGE BLOCK_DDL ' failed: 1213: Deadlock found when trying to get lock; try restarting transaction

End   of error output ----

ERROR: My exit status > 0 means I have hit some not expected problem.

Removing the file '/home/mleich/Server/10.4/bld_debug/mysql-test/var/tmp/run' and giving up.

I apologize in advance in case my mysqltest_background.sh shows somehow bad properties.