[erlang-bugs] Bug in the resolver?

Raimo Niskanen <>
Wed Apr 13 10:36:46 CEST 2011


On Tue, Apr 12, 2011 at 11:24:28AM +0200, Ahmed Omar wrote:
> I think this should solve it, but i think someone from OTP team can verify
> it
> 
> index de0f23b..9151cac 100644
> --- a/lib/kernel/src/inet_res.erl
> +++ b/lib/kernel/src/inet_res.erl
> @@ -552,10 +552,10 @@ do_udp_recv(Recv, IP, Port, Timeout) ->
> 
>  do_udp_recv(Recv, IP, Port, Timeout, Then) ->
>      case Recv(Timeout) of
> +       {ok,_} when Timeout =:= 0 ->
> +            {error,timeout};
>         {ok,{IP,Port,Answer}} ->
>             {ok,Answer,erlang:max(0, Timeout - now_ms(erlang:now(), Then))};
> -       {ok,_} when Timeout =:= 0 ->
> -           {error,timeout};
>         {ok,_} ->
>             Now = erlang:now(),
>             T = erlang:max(0, Timeout - now_ms(Now, Then)),

Would not that throw away an answer coming in at the last millisecond?

> 
> 
> On Tue, Apr 12, 2011 at 10:52 AM, Ahmed Omar <> wrote:
> 
> > Actually it might be a bug. There's a clause in do_udp_recv/4 that will
> > call do_upd_recv/5 with the value of Then as undefined.
> > If this value passed to now_ms/2 , it will crash. The crash reason is
> > converted to case_clause instead of function_clause because now_ms/2 is
> > inlined.
> >
> >
> > On Tue, Apr 12, 2011 at 10:27 AM, Ahmed Omar <>wrote:
> >
> >> Any steps to reproduce it?
> >>
> >>
> >> On Tue, Apr 12, 2011 at 8:25 AM, Evgeniy Khramtsov <>wrote:
> >>
> >>> We have a weird problem with inet_res in R14B02. Here is a snippet:
> >>>
> >>> =ERROR REPORT==== 2011-04-11 18:45:50 ===
> >>> ** State machine <0.6000.0> terminating
> >>> ....
> >>> ** Reason for termination =
> >>> ** {{case_clause,{{1302,533150,198860},undefined}},
> >>>    [{inet_res,do_udp_recv,5},
> >>>     {inet_res,query_udp_recv,6},
> >>>     {inet_res,query_ns,10},
> >>>     {inet_res,query_nss_dns,7},
> >>>     {inet_res,query_retries,6},
> >>>     {inet_res,res_getby_query,4},
> >>>     {inet_res,res_getby_search,6},
> >>>     {inet_res,getbyname,3}]}
> >>>
> >>> Any clue how to debug this?
> >>>
> >>> --
> >>> Regards,
> >>> Evgeniy Khramtsov, ProcessOne.
> >>> xmpp:
> >>>
> >>> _______________________________________________
> >>> erlang-bugs mailing list
> >>> 
> >>> http://erlang.org/mailman/listinfo/erlang-bugs
> >>>
> >>
> >>
> >>
> >> --
> >> Best Regards,
> >> - Ahmed Omar
> >> http://nl.linkedin.com/in/adiaa
> >> Follow me on twitter
> >> @spawn_think <http://twitter.com/#!/spawn_think>
> >>
> >>
> >
> >
> > --
> > Best Regards,
> > - Ahmed Omar
> > http://nl.linkedin.com/in/adiaa
> > Follow me on twitter
> > @spawn_think <http://twitter.com/#!/spawn_think>
> >
> >
> 
> 
> -- 
> Best Regards,
> - Ahmed Omar
> http://nl.linkedin.com/in/adiaa
> Follow me on twitter
> @spawn_think <http://twitter.com/#!/spawn_think>

> _______________________________________________
> erlang-bugs mailing list
> 
> http://erlang.org/mailman/listinfo/erlang-bugs


-- 

/ Raimo Niskanen, Erlang/OTP, Ericsson AB


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