zmq_close - Man Page

close 0MQ socket


int zmq_close (void *socket);


The zmq_close() function shall destroy the socket referenced by the socket argument. Any outstanding messages physically received from the network but not yet received by the application with zmq_recv() shall be discarded. The behaviour for discarding messages sent by the application with zmq_send() but not yet physically transferred to the network depends on the value of the ZMQ_LINGER socket option for the specified socket.

zmq_close() must be called exactly once for each socket. If it is never called, zmq_ctx_term() will block forever. If it is called multiple times for the same socket or if socket does not point to a socket, the behaviour is undefined.


The default setting of ZMQ_LINGER does not discard unsent messages; this behaviour may cause the application to block when calling zmq_ctx_term(). For details refer to zmq_setsockopt(3) and zmq_ctx_term(3).


This API will complete asynchronously, so not everything will be deallocated after it returns. See above for details about linger.

Return Value

The zmq_close() function shall return zero if successful. Otherwise it shall return -1 and set errno to one of the values defined below.



The provided socket was NULL.

See Also

zmq_socket(3) zmq_ctx_term(3) zmq_setsockopt(3) zmq(7)


This page was written by the 0MQ community. To make a change please read the 0MQ Contribution Policy at

Referenced By

zmq(7), zmq_ctx_shutdown(3), zmq_ctx_term(3), zmq_getsockopt(3), zmq_setsockopt(3).

08/13/2020 0MQ 4.3.3 0MQ Manual