NB: Fix for this bug also present in Stewart Smith' patchset: mysql-power-sync-mutex-lockword.patch

Multithreaded workload that includes writes to the database, causes a crash of the MariaDB server. This happens only if MariaDB was built with the Advance Tool Chain (ATC) and has been verified for a local 10.0.12 (release) build as well as a buildbot build of 10.0/rev4292.

To build with ATC, simply put /opt/at7.0/bin at the from of your $PATH and build like normal (cmake, make). The ATC contains enhanced versions of the GNU toolchain.

The last 5 observed crashes are triggered by abort() within InnoDB. Typical error log:

2014-07-16 11:15:19 fff8c207190 InnoDB: Assertion failure in thread 17590242013584 in file ut0lst.h line 271
InnoDB: Failing assertion: list.count > 0
InnoDB: We intentionally generate a memory trap.

Typical backtrace from corefile:

#0 0x00000fff8f583a40 in __pthread_kill (threadid=<optimized out>, signo=<optimized out>)
at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:61
#1 0x00000000109b5698 in my_write_core (sig=<optimized out>)
at /home/mariadb/mariadb-source/mariadb-10.0.12/mysys/stacktrace.c:457
#2 0x00000000103d5324 in handle_fatal_signal (sig=<optimized out>)
at /home/mariadb/mariadb-source/mariadb-10.0.12/sql/signal_handler.cc:262
#3 <signal handler called>
#4 0x00000fff8ed7f8f0 in __GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#5 0x00000fff8ed818f4 in __GI_abort () at abort.c:89
#6 0x0000000010124588 in ut_list_remove<ut_list_base<trx_t>, trx_t> (offset=568, elem=..., list=...)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/include/ut0lst.h:271
#7 0x00000000107ee004 in ut_list_remove<ut_list_base<trx_t>, trx_t> (offset=<optimized out>, elem=...,
list=...) at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/trx/trx0trx.cc:1151
#8 trx_commit_in_memory (lsn=365223679, trx=0xfff2800be08)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/trx/trx0trx.cc:1408
#9 trx_commit_low (trx=0xfff2800be08, mtr=<optimized out>)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/trx/trx0trx.cc:1605
#10 0x00000000107ee128 in trx_commit (trx=trx@entry=0xfff2800be08)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/trx/trx0trx.cc:1626
#11 0x00000000107ee8dc in trx_commit_for_mysql (trx=0xfff2800be08)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/trx/trx0trx.cc:1854
#12 0x00000000106c7468 in innobase_commit_low (trx=0xfff2800be08)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/handler/ha_innodb.cc:3929
#13 innobase_commit_ordered_2 (trx=trx@entry=0xfff2800be08, thd=thd@entry=0x1001b841858)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/handler/ha_innodb.cc:4038
#14 0x00000000106cae0c in innobase_commit (hton=0x1001ac45818, thd=0x1001b841858, commit_trx=<optimized out>)
at /home/mariadb/mariadb-source/mariadb-10.0.12/storage/xtradb/handler/ha_innodb.cc:4164
#15 0x00000000103d78c4 in commit_one_phase_2 (thd=thd@entry=0x1001b841858, all=all@entry=true,
is_real_trans=<optimized out>, trans=<optimized out>, trans=<optimized out>)
at /home/mariadb/mariadb-source/mariadb-10.0.12/sql/handler.cc:1514
#16 0x00000000103d9ca4 in ha_commit_one_phase (all=true, thd=0x1001b841858)
at /home/mariadb/mariadb-source/mariadb-10.0.12/sql/handler.cc:1495
#17 ha_commit_trans (thd=0x1001b841858, all=<optimized out>)
at /home/mariadb/mariadb-source/mariadb-10.0.12/sql/handler.cc:1372
#18 0x000000001031bea4 in trans_commit (thd=0x1001b841858)
at /home/mariadb/mariadb-source/mariadb-10.0.12/sql/transaction.cc:218
#19 0x000000001020b2f0 in mysql_execute_command (thd=thd@entry=0x1001b841858)
at /home/mariadb/mariadb-source/mariadb-10.0.12/sql/sql_parse.cc:4392

How to repeat

I have setup a test environment on the Power8 benchmark box (see internal wiki for details how to access the machine).

• log in as user mariadb.
• chdir to ~/benchmark/sysbench/series03.
• run runme.sh.

This will fire up a server from ~/mariadb-install/mariadb-10.0.12-atc, create a single table for sysbench OLTP and run a read/write OLTP test with 8 threads. Single/double threaded load did not crash, with 4 or more threads crashes start to happen.

For convenience I symlinked the datadir and mysqld binary. So you can run gdb like so

~/benchmark/sysbench/series03 $/opt/at7.0/bin/gdb mysqld datadir/core...