[zeromq-dev] PUB/SUB assert(get_load () == 0) in zmq_ctx_destroy

[Martin Townsend]

Apologies I forgot to say that I'm using v4.0.4 with epoll.

On 01/07/14 11:44, Martin Townsend wrote:
> Hi,
>
> I'm getting an assert when trying to gracefully exit
>
> At the bottom of the mail is my pthread code that handles subscribing in
> a pub/sub model and reads power values.  On SIGINT and SIGTERM it sets
> quit to 1 and the thread exits but I get an exception on the call to
> zmq_ctx_destroy (zcontext);
>
> Assertion failed: get_load () == 0 (poller_base.cpp:31)
> Thread [2] (Suspended: Signal 'SIGABRT' received. Description: Aborted.)
>       15 __GI_raise() raise.c:56 0x482c9ff4
>       14 __GI_abort() abort.c:89 0x482ce4d0
>       13 zmq::zmq_abort() err.cpp:74 0x4803c558
>       12 zmq::poller_base_t::~poller_base_t() poller_base.cpp:31 0x480519d4
>       11 zmq::epoll_t::~epoll_t() epoll.cpp:42 0x4803b8f8
>       10 zmq::epoll_t::~epoll_t() epoll.cpp:50 0x4803b930
>       9 zmq::io_thread_t::~io_thread_t() io_thread.cpp:39 0x4803d2f0
>       8 zmq::io_thread_t::~io_thread_t() io_thread.cpp:40 0x4803d3ac
>       7 zmq::ctx_t::~ctx_t() ctx.cpp:82 0x48033a9c
>       6 zmq::ctx_t::terminate() ctx.cpp:153 0x480367d4
>       5 zmq_ctx_term() zmq.cpp:171 0x4806f13c
>       4 zmq_ctx_destroy() zmq.cpp:241 0x4806f3e0
>       3 zsub_thread() xcoapd.c:470 0x10002b9c
>       2 start_thread() pthread_create.c:314 0x48095180
>       1 clone() clone.S:65 0x48383e88
>
> Am I doing anything incorrect below?  If I put a sleep(4) before
> destroying the context I don't get the assert so I'm suspecting a race
> condition somewhere.  I'm running on a 100MHz Microblaze.
>
> /* ZeroMq Subscriber task */
> static void * zsub_thread(void * arg) {
>       int rc;
>
>       zcontext = zmq_ctx_new ();
>       zmq_ctx_set (zcontext, ZMQ_MAX_SOCKETS, 256);
>       int max_sockets = zmq_ctx_get (zcontext, ZMQ_MAX_SOCKETS); assert
> (max_sockets == 256);
>
>       subscriber = zmq_socket (zcontext, ZMQ_SUB);
>       printf("Subscribing\n");
>       rc = zmq_connect (subscriber, "ipc://xpwrd.ipc");
>       assert (rc == 0);
>       // Subscribe to zipcode, default is NYC, 10001
>       char *filter = "Pwr";
>       rc = zmq_setsockopt (subscriber, ZMQ_SUBSCRIBE, filter, strlen
> (filter));
>
>
>       while(!quit) {
>           char buf[32];
>           char *s;
>           int unknown_err_count;
>           zmq_pollitem_t items [] = {
>               { subscriber, 0, ZMQ_POLLIN, 0 }
>           };
>
>           rc = zmq_poll (items, 1, 1000);
>           if(rc == 1) {
>               /* As we only have one poll item we can safely call recv on
> this */
>               unknown_err_count = 0;
>               s = s_recv (subscriber, buf, sizeof(buf));
>               if(s)
>                   sscanf(s, "Pwr:%04dW T:%dC", &pwr, &temp);
>
>               printf("Pwr:%04dW T:%dC\n", pwr, temp);
>           } else if(rc == 0) {
>               unknown_err_count = 0;
>               printf("Poller Timed out\n");
>           } else {
>               /* error */
>               if(errno == ETERM) {
>                   printf("Poller has detected that socket was terminated\n");
>                   break;
>               } else if(errno == EFAULT) {
>                   printf("zmq_poll has invalid parameters!!!!\n");
>                   break;
>               } else if(errno != EINTR) {
>                   /* Ignore EINTR as we will just poll again on next
> iteration of
>                    * loop, all other errors are undocumented in zmq so
> print a
>                    * message and set a flag and if it occurs 3 times exit
> loop */
>                   printf("Poller returned unknown error %d", errno);
>                   printf("%s\n", strerror(errno));
>                   unknown_err_count++;
>                   if(unknown_err_count == 3) {
>                       break;
>                   }
>               }
>           }
>       }
>
>       printf("Subscriber thread closed\n");
>       zmq_close (subscriber);
>       zmq_ctx_destroy (zcontext);
>
>       return (void *)0;
> }
>
>
> Best Regards,
> Martin.
>
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