On Wed, 2011-02-16 at 16:40 +0000, Steven van der Vegt wrote:
> Hi Folks,
>
> I wanted to test the 2.6c version on a testsystem of ours but I ran into
> trouble. Every time 1 request was handled I got this error:
>
> MONITOR: worker exited on signal 11, restarting...
>
> After some research I found out it was the memcopy in do_http() which causes
> the error:
>
> from_host = ((thr_arg *)arg)->from_host;
> memcpy(&from_host_addr, from_host.ai_addr, from_host.ai_addrlen);
> from_host.ai_addr = (struct sockaddr *)&from_host_addr;
>
> The value from_host.ai_addrlen was equal to 5394258 and after some debugging
> it seems the whole struct contained bogus.
>
> Ok, let's find out why?
>
> The do_http() function is called from thr_http() which has some strange while
> loop in it. It fetches work from a queue with the call get_thr_arg() but this
> call is allowed to return a NULL value sometimes. If this happens than ask
> again...
> Well, this wasn't a NULL value so there must be something else going on.
> Maybe the queue?
>
> The code contained some errors (as far as my concurrent and queue knowledge
> go's). I reimplemented them to the following code. It solved my errors and I
> think the strange while-loop in the thr_http function is not needed anymore.
>
> Can you please comment on my changes?
>
> int
> put_thr_arg(thr_arg *arg)
> {
> thr_arg *res;
>
> if((res = malloc(sizeof(thr_arg))) == NULL) {
> logmsg(LOG_WARNING, "thr_arg malloc");
> return -1;
> }
> memcpy(res, arg, sizeof(thr_arg));
> (void)pthread_mutex_lock(&arg_mut);
>
> res->next = NULL;
>
> if (last == NULL) {
> first = last = res;
> } else {
> last->next = res;
> last = res;
> }
>
> pthread_cond_broadcast(&arg_cond);
> (void)pthread_mutex_unlock(&arg_mut);
> return 0;
> }
>
> /*
> * get a request from the queue
> */
> thr_arg *
> get_thr_arg(void)
> {
> thr_arg *res = NULL;
>
> (void)pthread_mutex_lock(&arg_mut);
> while (first == NULL)
> (void)pthread_cond_wait(&arg_cond, &arg_mut);
>
> res = first;
> if((first = res->next) == NULL)
> last = NULL;
> else
> pthread_cond_signal(&arg_cond);
>
> (void)pthread_mutex_unlock(&arg_mut);
>
> return res;
> }
>
> Thanks!
>
> Kind regards,
>
> Steven van der Vegt
>
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>From what I see, you have made two changes:
1. you have moved the NULL check from the caller in http.c to the getter
in pound.c (a NULL check is required in any case, as the condition
wake-up may occur even when there is no data to be consumed)
2. you have replaced the cond_signal with a cond_broadcast in the
enqueing function
The first change should make no difference (it is just moving the actual
check to another place). The second will cause more threads to wake-up,
quite often more than are required. I must admit am not at all clear how
should this help.
--
Robert Segall
Apsis GmbH
Postfach, Uetikon am See, CH-8707
Tel: +41-32-512 30 19
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