MySQL Bugs: #83102: deadlock in mysql_server_init on restarting embedded server in the same process

Bug #83102	deadlock in mysql_server_init on restarting embedded server in the same process
Submitted:	22 Sep 2016 15:58	Modified:	22 Sep 2016 17:17
Reporter:	Daniel Beer	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server: Embedded Library ( libmysqld )	Severity:	S3 (Non-critical)
Version:	5.6.33	OS:	Red Hat (6.6)
Assigned to:		CPU Architecture:	Any

Description:
mysql_client_test_embedded hangs when running test "test_embedded_start_stop". The issue seems to be a deadlock in mysql_server_init, which is stuck waiting on log_sys->checkpoint_lock.

Stack trace:
#0  0x00d43430 in __kernel_vsyscall ()
#1  0x00a9e43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#2  0x0877b794 in os_cond_wait(pthread_cond_t*, os_fast_mutex_t*) ()
#3  0x0877bd67 in os_event_wait_low(os_event*, long long) ()
#4  0x0883e0ed in sync_array_wait_event(sync_array_t*, unsigned long) ()
#5  0x08840455 in rw_lock_s_lock_spin(rw_lock_t*, unsigned long, char const*, unsigned long) ()
#6  0x087632b8 in rw_lock_s_lock_func ()
#7  0x08763704 in pfs_rw_lock_s_lock_func ()
#8  0x08765bfa in recv_synchronize_groups() ()
#9  0x08769fde in recv_recovery_from_checkpoint_start_func(unsigned long long, unsigned long long) ()
#10 0x0883c348 in innobase_start_or_create_for_mysql() ()
#11 0x086f92e8 in innobase_init(void*) ()
#12 0x08316275 in ha_initialize_handlerton(st_plugin_int*) ()
#13 0x08474521 in plugin_initialize(st_plugin_int*) ()
#14 0x08474ee7 in plugin_init(int*, char**, int) ()
#15 0x082ccf6c in init_server_components() ()
#16 0x082d1ba7 in init_embedded_server ()
#17 0x0828d991 in mysql_server_init ()
#18 0x082415ba in test_embedded_start_stop ()
#19 0x0821b7bc in main ()

How to repeat:
Build and run mysql_client_test_embedded with mysql 5.6.33:

$ mkdir /tmp/testdb
$ mysql_install_db --datadir=/tmp/testdb
$ mysql_client_test_embedded --server-arg=--datadir=/tmp/testdb test_embedded_start_stop

#####################################
client_connect  
#####################################

 Establishing a connection to '' ...OK
Connected to MySQL server version: 5.6.33-embedded-debug (50633)

 Creating a test database 'client_test_db' ...OK

#####################################
1 of (1/1): test_embedded_start_stop  
#####################################

#####################################
client_disconnect  
#####################################

 closing the connection ...OK

(hangs indefinitely)

Thank you for the bug report.

http://dev.mysql.com/doc/refman/5.6/en/libmysqld-restrictions.html

23.7.2 Restrictions When Using the Embedded MySQL Server

<cut>

InnoDB is not reentrant in the embedded server and cannot be used for multiple connections, either successively or simultaneously.

Thanks for the update, seems like this test case should be removed from mysql_client_test in that case. I'll put in a separate feature request for this.