Re: Is mysql_real_connect thread safe?

[Guilhem Bichot]

Hello,

On Wed, Jun 27, 2007 at 10:27:18AM -0700, Dhammika Pathirana wrote:
> I'm working on a multi-threaded daemon written in C/C++ for FreeBSD.
> This daemon uses libmysqlclient_r.so.15 to query a mysql db. Both
> libmysqlclient_r and the daemon are compiled with -lpthread and all
> threads are initialized with mysql_init.
> If I startup this daemon process at system bootup (through rc.d) then
> I get the following core, but it seems to work fine if I start it
> manually (after system bootup). Would really appreciate any help on
> this.
> 
> #0  0x2846926f in pthread_testcancel () from /usr/lib/libpthread.so.1
> (gdb) bt
> #0  0x2846926f in pthread_testcancel () from /usr/lib/libpthread.so.1
> #1  0x28461856 in pthread_mutexattr_init () from /usr/lib/libpthread.so.1
> #2  0x00000000 in ?? ()

http://dev.mysql.com/doc/refman/5.0/en/threaded-clients.html
says:

 To get things to work smoothly you have to do the following:

   1. Call mysql_library_init() before any other MySQL functions. It
is not thread-safe, so call it before threads are created, or protect
the call with a mutex.
   2. Arrange for mysql_thread_init() to be called early in the thread
handler before calling any MySQL function. If you call mysql_init() or
mysql_connect(), they will call mysql_thread_init() for you.
   3. In the thread, call mysql_thread_end() before calling
pthread_exit(). This frees the memory used by MySQL thread-specific
variables.

From what you are saying you already have done 2); but do you also
have 1) and 3) ? 

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