[erlang-questions] Erlang message passing delay after abnormal network disconnection

[Eranga Udesh]

Excellent, the net_tick_time environment variable works. Thanks for the
advice.
Still I appreciate if I can know the behavior of inet_drv based on the
questions I asked in my previous email.

Cheers,
- Eranga



On Tue, Mar 4, 2008 at 10:28 PM, Kenneth Lundin <kenneth.lundin@REDACTED>
wrote:

> When connectivity is broken abnormally the sending node will detect
> this within 45-60 seconds as default. This can be changed with the
> net_tick_time environment variable in application kernel.
> Before the detection the sending node will try to send the message and
> if not possible it will be queued in the inet-driver. If the queue
> gets bigger than a certain max a so called "busy port" will occur
> which will block the sending Erlang process.
> This occurs when the receiving side of the distribution socket does
> not read what is
> sent to it which is the case when you have no connectivity.
>
> another scenario is that the receiving node is detected as down and
> an auto connect (including handshake) is performed for the first
> message sent after
> the broken connection. This will take in the order of 10 seconds before
> timeout.
>
> If you want to avoid this for a very crucial process (i.e avoid
> blocking of that particular Erlang process) you can send the message
> with erlang:send_nosuspend/2 or 3. Warning! these functions should be
> used with extreme care, Read the manual!
>
> Note that this has nothing to do with HiPE (i.e native code).
> An abnormal termination of the connectivity for example by unplugging
> the network cable will have this effect.
>
> /Kenneth Erlang/OTP team Ericsson
>
> On 3/4/08, Eranga Udesh <eranga.erl@REDACTED> wrote:
> > The problem occurs when the network connectivity is broken (abnormally).
> The
> > receiving node is not receiving messages. The sending  processes are
> > blocked, since those message delivery calls (gen_event:notify/s, etc)
> are
> > waiting for about 10 secs to return. We checked the implementation of
> such
> > calls and notice, the functions are waiting until the messages are
> delivered
> > to the receiving node. Is there's a way (a system flag may be) to avoid
> such
> > blocking and to return immediately?
> >
> > BRgds,
> > - Eranga
> >
> >
> >
> >
> > On Mon, Mar 3, 2008 at 6:51 PM, Chandru
> > <chandrashekhar.mullaparthi@REDACTED> wrote:
> > >
> > >
> > >
> > > On 03/03/2008, Eranga Udesh <eranga.erl@REDACTED> wrote:
> > > > Hi,
> > > >
> > > > I am experiencing a high message passing delay between 2 Erlang
> nodes,
> > after
> > > > an abnormal network disconnection. Those 2 nodes are in a WAN and
> there
> > are
> > > > multiple Hubs, Switches, Routes, etc., in between them. If the
> message
> > > > receiving Erlang node stopped gracefully, the delay doesn't arise.
> Doing
> > > > net_adm:ping/1 to that node results no delay "pang". However
> > > > gen_event:notify/2, gen_server:cast/2, etc. are waiting for about 10
> > seconds
> > > > to return.
> > > >
> > > > What's the issue and how this can be avoided?
> > >
> > > Have you tried putting a snoop to see whether the delay is on the
> > > sending/receiving side?
> > >
> > > This might be useful:
> > http://www.erlang.org/contrib/erlsnoop-1.0.tgz
> > >
> > > cheers
> > > Chandru
> > >
> >
> >
> > _______________________________________________
> > erlang-questions mailing list
> > erlang-questions@REDACTED
> > http://www.erlang.org/mailman/listinfo/erlang-questions
> >
>
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