[erlang-questions] R1502 ssl dropping byte(s)?

sasa <>
Mon Nov 5 15:32:18 CET 2012


Thank you for the response.

Obviously, active once should resolve my problem, and I will modify the
code accordingly.

In the meantime, I have resolved the issue by raising ssl:recv timeout to
15 seconds. In my environment this essentially means that timeout does not
occur.
I'd like to stress that in almost 2 years of production, I have never
experienced this issue with R14.
It is also very strange that I was always loosing first byte of the message
and not more. Which still leads me to believe that some bug might have been
introduced regarding passive sockets.

However, active once seems like a cleaner solution, and I will therefore go
ahead with that approach.

Best regards,
Sasa


On Mon, Nov 5, 2012 at 11:08 AM, Ingela Andin <>wrote:

> Hi!
>
> The only thing that might have changed between R14 and R15 is the
> timing so that this happens to you more often, but using a timeout to
> recv can cause
> you to sort of loose data  as you will not stop the recv of being
> processed  by ssl, only cause recv to return early. This is much like
> if you time out  a POST request to a webserver the request  may still
> have reached the webserver and have been executed on the server side.
> I  think that if you do not want to hang
> in recv you should use active once instead passive receive (recv).
>
> Regards Ingela Erlang/OTP team - Ericsson AB
>
>
> 2012/11/2 sasa <>:
> > Hello,
> >
> > Today I have migrated my production servers to R15B02 (previously they
> ran
> > on R14).
> > Generally, everything works fine. However, I do notice a strange behavior
> > occasionally.
> > I'm not sure if Erlang is to blame, but it's a strange coincidence that
> this
> > started occurring after the migration, and system is in production for
> > almost two years.
> >
> > In my system, I am constantly fetching some data from the external
> provider
> > via ssl. The code is roughly following:
> >
> > loop(Socket) ->
> >    ssl:recv(Socket, 0, 5000),
> >    ...
> >    loop(Socket).
> >
> > After switching to R15, I have noticed that occasionally, a byte gets
> > "lost". This always happens after 5 or 10 seconds which leads me to
> > suspicion, that possibly some race condition occurs in ssl.
> > Could it be that the timeout occurs just as the bytes start to arrive,
> and
> > the first one is discarded?
> > Again, I didn't notice this behavior on R14.
> >
> > Best regards,
> > Sasa
> >
> > _______________________________________________
> > erlang-questions mailing list
> > 
> > http://erlang.org/mailman/listinfo/erlang-questions
> >
>
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