[zeromq-dev] zmq-signaler-port-sync

[KIU Shueng Chuan]

Hi Pau, a fix for the assertion on connection to port 5905 is in trunk
branch.

I think the dangling critical section possibility could be fixed by
changing the Event to a Mutex. When an assertion occurs the mutex would
just be abandoned. However this change will cause backward compatibility
issues with older versions.
 On Jan 22, 2013 2:04 AM, "Pieter Hintjens" <ph at imatix.com> wrote:

> Hi Pau,
>
> So there are two different problems here, one is that we're hitting a
> socket limit on WXP, and the other is that the asserts are happening
> inside a critical section.
>
> I don't think we can fix the first one easily but we can presumably
> assert in a smarter way. Do you want to try making a patch for this?
>
> -Pieter
>
> On Mon, Jan 21, 2013 at 6:23 PM, Pau <pau at teleopsia.com> wrote:
> >
> > Hi,
> >
> >
> > I am using (not yet in production) ZMQ on Windows and I have found what
> > I think is a big problem for Windows users.
> > We use WXP and W7 and Visual C++ different versions. ZMQ version 3.2.0
> > (as far as I see the same problem happens in 3.2.2)
> >
> > I do not fully understand ZMQ internals but I've seen that every time a
> > socket is created the function make_fdpair(..) is called and in
> > signaler.cpp(line244) a system event "zmq-signaler-port-sync" is created.
> > This event is used as a system-wide critical section and, so all
> > applications that try to create an event will WaitForSingleObject (sync,
> > INFINITE) until  SetEvent (...) is called.
> > The problem is that the code between:
> >   HANDLE sync = CreateEvent (NULL, FALSE, TRUE, TEXT
> > ("zmq-signaler-port-sync"));
> > and
> > SetEvent (sync);
> > is full of wsa_asserts(..) that will terminate the application if
> > something goes wrong.
> >
> > It is clear that terminating the application not leaving the system-wide
> > critical section is a bad idea because all applications in the system
> > will hang and you will have to stop all them to start again.
> > I understand that no errors should happen but anyway to escape from the
> > error is not a good idea in this case.
> >
> > I do not know all possible reasons to generate a fatal wsa_assert(..)
> > but there is at least one:
> >
> > I have seen that in XP it is possible that line 301  rc = connect (*w_,
> > (sockaddr *) &addr, sizeof (addr)); returns an error when a socket tries
> > to connect to 5905 and this has happened many times.
> > Windows uses port numbers starting near 1400 and XP has a limit at 5000.
> > In W7 this does not look as a problem because maximum is 65000
> > It sounds as if the number was big enough but apart from the fact that
> > ZMQ uses a big number of connections (at least in my tests) I have
> > experienced that Windows jumps port numbers by 7, so 5000 happens
> > sometimes with catastrophic consequences.
> >
> > best,
> >
> > Pau Ceano
> > _______________________________________________
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> > zeromq-dev at lists.zeromq.org
> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
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