[zeromq-dev] zmq_ctx_term vs zmq_ctx_destroy vs zmq_ctx_shutdown

MinRK benjaminrk at gmail.com
Sun Jun 15 20:47:59 CEST 2014


To add further confusion, PyZMQ distinguishes term from destroy (pyzmq used
the term ‘destroy’ before zmq did).

In pyzmq, ctx.term just calls the underlying libzmq zmq_ctx_term (née
zmq_term) function, which blocks until all sockets are closed. ctx.destroy,
on the other hand, closes all sockets prior to calling term. czmq has a
similar behavior for destroy. After these destroy behaviors were
established, libzmq added a zmq_ctx_destroy function, but just as a rename
of zmq_term, which causes confusion like this, hence the change replacing
zmq_ctx_destroy with the less confusing zmq_ctx_term.

-MinRK
​


On Sun, Jun 15, 2014 at 6:03 AM, Pieter Hintjens <ph at imatix.com> wrote:

> zmq_term/zmq_init are an older deprecated API. We switched to a more
> consistent model for the API in 3.2, so zmq_ctx_xxx for all methods
> that work with contexts, like zmq_msg_xxx for all methods that work on
> messages.
>
> zmq_ctx_destroy was the initial choice for the termination method.
> However people pointed out that the context isn't actually destroyed,
> it's terminated, so we added _term() as a synonym. To be honest I'm
> not keen on _term() as it seems inconsistent for no benefit. We
> destroy sockets and contexts asynchronously... I'd prefer _destroy().
>
> More usefully, we later added _shutdown() method that stops the
> context but leaves it in existence; this allows a two-stage shutdown,
> with signals being sent to all sockets waiting on blocking operations,
> and then allowing the app to call zmq_ctx_destroy/term when wanted.
>
> -Pieter
>
> On Sat, Jun 14, 2014 at 3:34 PM, Indradhanush Gupta
> <indradhanush.gupta at gmail.com> wrote:
> > Hello,
> >
> > I consulted the docs for zmq_ctx_term and zmq_ctx_destroy, in the API
> > version 4.0 and it appears to be both have the same description. What is
> the
> > difference between the two?
> > I'm using pyzmq, by the way.
> >
> > When I called zmq.Context.term() the call blocks indefinitely, while
> > zmq.Context.destroy() returns immediately. I am shutting down my IOLoop,
> > then closing all open sockets by hand and only then calling one of the
> > above.
> >
> > What is the difference between the two calls? Also, it appears
> > zmq_ctx_destroy is going to be deprecated according to the 4.1 dev API
> docs.
> > Why is term() blocking while destroy() doesn't?
> >
> > I'm also confused as to when should I call shutdown, destroy or term?
> >
> > If it helps, I have not set any LINGER option on any of the sockets.
> >
> > Thanks,
> > --
> > Indradhanush Gupta
> > (dhanush on irc)
> >
> >
> > _______________________________________________
> > zeromq-dev mailing list
> > zeromq-dev at lists.zeromq.org
> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
> >
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