Hi, Thanx for responding.
Only one worker thread was accesing MYSQL* myHdl. Nevertherless i have placed mutexes around all calls involing MYSQL*. main-thread: Defined MYSQL* myHdl as global variable and called mysql_init(), and mysql_connect(); worker: Defined MYSQL_RES* res and used myHdl to query with no problems. Crashes upon mysql_num_res or mysql_fetch_rows. gdb gives: Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 3076 (LWP 23491)] 0x400519e3 in mysql_fetch_row () from /usr/lib/libmysqlclient_r.so.10 (gdb) bt #0 0x400519e3 in mysql_fetch_row () from /usr/lib/libmysqlclient_r.so.10 #1 0x08054d40 in th_connection () #2 0x40036fef in pthread_start_thread () from /lib/i686/libpthread.so.0 #3 0x400370df in pthread_start_thread_event () from /lib/i686/libpthread.so.0 -----Original Message----- From: Eric Bergen <[EMAIL PROTECTED]> To: darren <[EMAIL PROTECTED]> Date: Wed, 30 Jun 2004 20:06:40 -0500 Subject: Re: threading problems in linux C client If you have multiple threads accessing the same connection remember to make sure that only one thread enters mysql_query() mysql_connect() or mysql_store_result() after you store the result another thread will be able to use that connection without problems. -Eric On Wed, 30 Jun 2004 11:01:35 +0000, darren <[EMAIL PROTECTED]> wrote: > > Hi all, > > I am writing a multi-threaded client that requires shared access to a single MySQL > connection. The environment is Redhat 7.3 with the patched > mysql-3.23.58-2.71.i386.rpm installed and compiled with -l libmysqlclient_r. > > The connection is made from the main thread and a MYSQL_RES* myres declared from the > child thread is used to fetch results back to the thread. I get a Segmentation fault > the first instance my child thread (only one) accesses MYSQL_RES through > mysql_num_rows(myres). (gdb informed me that this is due to mysql_num_rows from > libmysqlclient_r.so.10) > > I have read a few docs about writing MySQL multi-threaded clients and have called > my_init() in my main prog and my_thread_init() at the first line of my thread > handler. > > Any ideas? > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
