Re: Question about threading implementation

[Andrew Hacking <ahacking@xxxxxxxxxxxxxxx>]

Calling sleep() in a multi-threaded program is probably not safe since
it suspends the process, not just the thread.
You should always call nanosleep() in multi-threaded apps.

The core dump is not pretty through....

-Andrew.

On Sun, 2005-03-06 at 09:00, Jonathon McKitrick wrote: 
> Hi all,
> 
> I've been trying to port my new Linux app from work to run on BSD so I can
> work on it at home.  It links with -pthread on Linux, and -lc_r on FreeBSD.
> It has a mutex, a lock, and a thread.  The thread runs a loop that sleep()s
> a second for 5 seconds, to simulate connecting to the instrument it will
> control.  Then it signals a condition.
> 
> struct thread_params {
>         int             tp_flags;
>         pthread_t       tp_tid;
>         pthread_mutex_t tp_lock;
>         pthread_cond_t  tp_cond;
> };
> 
> void *thread_init(void *arg)
> {
>         struct thread_params *tp = (struct thread_params *)arg;
>         int i;
> 
>         pthread_mutex_lock(&tp->tp_lock);
>         printf("Started thread.\n");
> 
>         for (i = 1; i < 5; i++)
>         {
>                 printf("Sleeping.\n");
>                 sleep(1);
>         }
> 
>         printf("Waking.\n");
> 
>         printf("Stopping thread.\n");
> 	pthread_cond_signal(&tp->tp_cond);
> 	pthread_mutex_unlock(&tp->tp_lock);
> 
> 	printf("Stopped thread.\n");
> 	return 0;
> }
> 
> void MyClass::initialize()
> {
>         static struct thread_params tp;
>         int err;
> 
>         tp.tp_cond = PTHREAD_COND_INITIALIZER;
>         tp.tp_lock = PTHREAD_MUTEX_INITIALIZER;
> 
>         err = pthread_mutex_lock(&tp.tp_lock);
>         if (err)
>                 printf("Error on lock:  %d\n", err);
>         err = pthread_create(&tp.tp_tid, NULL, thread_init, &tp);
> 	if (err)
> 	        printf("Error on thread create: %d\n", err);
>         else
>         {
>                 printf("Thread created.\n");
> 		printf("Waiting...\n");
> 
> 		pthread_cond_wait(&tp.tp_cond, &tp.tp_lock);
> 
> 		printf("Signaled!\n");
> 		pthread_mutex_unlock(&tp.tp_lock);
> 
> 		printf("Thread joining.\n");
> 		pthread_join(tp.tp_tid, NULL);
> 		printf("Thread joined.\n");
> 	}
> }
> 
> Linking with libc_r under FreeBSD, the thread runs for 5 seconds, then
> signals the condition.
> 
> Thread created.
> Waiting...
> Started thread.
> Sleeping.
> Sleeping.
> Sleeping.
> Sleeping.
> Waking.
> Stopping thread.
> Stopped thread.
> Signaled!
> Thread joining.
> Thread joined.
> 
> --------------------------------------
> When I use -lthread_xu, I get this:
> 
> Error on lock:  22
> Thread created.
> Started thread.
> Waiting...
> Sleeping.
> Signaled!
> Thread joining.
> Thread joined.
> 
> ----------------------------------------
> There is no 5 second delay from the thread.
> 
> When I use -lc_r, I get this:
> 
> Fatal error 'Failed to initialise garbage collector mutex or condvar' at
> line ? in file /usr/src/lib/libc_r/uthread/uthread_init.c (errno = ?)
> zsh: abort (core dumped)  app
> 
> What am I doing wrong?
> 
> Jonathon McKitrick
> --
> My other computer is your Windows box.