[zeromq-dev] zmq_term hanging

[Morten Møller Riis]

Thank you Pieter!

Could I get you to expand a bit on why my design is poor? Is it just because that it will linger forever, or am I doing something completely wrong here?

I'll look into czmq.

I still have the problem if I set the linger to 0 before binding the socket though.


  int linger = 0;
  zmq_setsockopt(zmq_sock, ZMQ_LINGER, &linger, sizeof linger);
  rc = zmq_bind(zmq_sock, LISTEN_ADDRESS);

Moving this to just before closing the socket doesn't help:

  int linger = 0;
  zmq_setsockopt(zmq_sock, ZMQ_LINGER, &linger, sizeof linger);
  zmq_close(zmq_sock);


?

Best regards
Morten Møller Riis



On Sep 24, 2013, at 5:14 PM, Pieter Hintjens <ph at imatix.com> wrote:

> This is a (rather poor) design choice in libzmq where the default
> linger on sockets is infinite, and the library does not properly
> handle socket shutdown. You've got two options. One, set linger=0 on
> the socket before closing it. Two, use CZMQ, which does this
> automatically on sockets.
> 
> -Pieter
> 
> On Mon, Sep 23, 2013 at 7:43 AM, Morten Møller Riis
> <mortenmoellerriis at gmail.com> wrote:
>> Hi guys
>> 
>> I'm having trouble catching SIGTERM and closing socket and context.
>> 
>> I have the following code (I've trimmed it down since a lot of other stuff
>> is happening). I use the global variable term_flag to break the main loop
>> when the program receives SIGTERM.
>> 
>> The problem is that when sending SIGTERM to the program it hangs at
>> zmq_term(). Sending SIGTERM once more closes the program. Why is this
>> happening?
>> 
>> 
>> int term_flag = 1;
>> 
>> void term(int signum)
>> {
>>    fprintf(log_fp, "Received %i, closing context and socket...\n", signum);
>>    fprintf(log_fp, "Exiting.\n");
>>    term_flag = 0;
>> }
>> 
>> int main(int argc, char **argv) {
>>  ...
>> 
>>  signal(SIGTERM, term);
>>  signal(SIGINT, term);
>> 
>>  …
>> 
>>  while(term_flag) {
>>    …
>>    rc = zmq_recv(zmq_sock, &msg, 0);
>>    if(rc!=0) break;
>>    …
>>  }
>> 
>>  zmq_close(zmq_sock);
>>  zmq_term(zmq_ctx); // hangs here
>>  ...
>>  return 0;
>> }
>> 
>> 
>> Best regards
>> Morten Møller Riis
>> 
>> 
>> 
>> 
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>> zeromq-dev at lists.zeromq.org
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>> 
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