The issue was that we sent two different signals to different threads
after each other. The DEBUG_SYNC functionality cannot handle this (as
the signal is stored in a global variable) and the first one can get
lost.
Fixed by using the same signal for both threads.
As a part of this MDEV following changes were made:
1) Mariadb named executables used instead of mysql named executables in scripts
2) renamed mysql-test-run and mysql-stress-test to mariadb-test-run and
mariadb-stress-test and created a symlink.
When acquiring SNW/SNRW/X MDL lock DDL/admin statements may abort pending
thr lock in concurrent connection with open HANDLER (or delayed insert
thread).
This may lead to a race condition when table->alias is accessed
concurrently by such threads. Either assertion failure or memory leak
is a practical consequence of this race condition.
Specifically HANDLER is opening a table and issuing alias.copy(), while
DDL executing get_lock_data()/alias.c_ptr()/realloc()/realloc_raw().
Fixed by perforimg table->init() before it is published via
thd->open_tables.
Quick fix: run mysql-stress-test.pl via a wrapper test
Amend mtr to run just that test when using --stress
Updated mysql-stress-test.pl to exit(1) if wrong options
mysql-test/suite/stress/t/ddl_ndb.test:
The default connection should be "default connection".
If there is no this statement added, the default connection is server1.
