All, Thanks for all of the suggestions. Actually, Eric hit the nail on the head - I was forgetting to link to libpthread. Knew I had to, remember thinking that I need to change my makefile and add libpthread to the list of libraries that I was linking to. Would have bet money that I did this. Oh well....
Now this bring up an interesting question - how can a program using pthread compile cleanly when it is not linked to libpthread? I would expect unresolved externals on all pthread functions? George -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Huber, George K RDECOM CERDEC STCD SRI Sent: Thursday, April 07, 2005 1:02 PM To: [email protected] Subject: Multithreading with C++ All, This may be a little off topic, but I though I would try here first. I am writting a multi-threaded program and would like to have each thread `managed' by a class. I have attempted to do this like this, using the pthreads library: <code> ====================begin cthread.h class CThread { public: CThread(void*); ~CThread(); .... private: static CThread* m_pThis; pthread_t m_tid; static void* threadfun(void*); .... } ==================== begin cthread.cpp CThread* CThread::m_pThis = NULL; CThread::CThread(void* arg) { int ret; m_pThis = this; if(0 != (ret = pthread_create(&m_tid, NULL, threadfun, arg))) { fprintf(stderr, "Thread creation failed"); } } void* threadfun(void* arg) { printf("Starting thread\n"); .... } </code> The code compiles without warnings or errors, except when I try and run the application I get a segmentation fault at the pthread_create. Trying to run under GDB, I am able to examine the value of the variables and they seem consisten with what I would expect // stop on the pthread_create line in the constructor... (gdb) print m_pThis $1 = (CThread*) 0xfee756b0 (gdb) print this $2 = (CThread*0xfee756b0 (gdb) print m_tid $3 = 134514818 // to be expected because I have not initialized m_tid yet (gdb) print &m_tid $4 = (pthread_t*)0xfee756d8 (gdb) print threadfun $5=&CThread::threadfun(void*) // attempt the pthread_create line .... Program received signal SIGSEGV, Segmenatation fault 0x0000000 in ?? () (gdb) where #0 0x00000000 in ?? ( ) #1 0x0804a6bb in CThread (this=0xfee756b0, args=0x0) at .... #2 0x08049aad in daemon_main(argc=3, argv=0xfeec42d4) at .... #3 0x08049193 in main(argc=3, argv=0xfeec42d3) at main.cpp: 83 Any idea on what is going on, or how to fix? Thanks, George Huber - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
