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<p class="MsoNormal">Hi All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Looks like I have a problem with the erroneous result of gen_tcp:recv/2, as it returns {error,closed} instead of my expectation of {error,econnreset}.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I can reproduce my problem by:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">1, starting a server application and forcing it into a busy state when it is listening but not accepting connections<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">2,starting 1000 clients (in Erlang) that connect to the server, filling the TCP listen backlog of the server.<o:p></o:p></p>
<p class="MsoNormal">When the backlog is filled and after some time (~2 minutes), the Erlang connections return {error,closed}.<o:p></o:p></p>
<p class="MsoNormal">This is what I do in Erlang:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">fun()->{ok,Socket}= TCPCONNECT(HOST,PORT),<br />
ok=gen_tcp:send(Socket,<<"SOMEDATA…”>>),<br />
io:format("~p:~p\n",[self(),gen_tcp:recv(Socket,100)])<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">end.<o:p></o:p></span></p>
<p class="MsoNormal">spawn this 1000 times.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">3, a native client of the service however tells me that the connection was reset by peer.<o:p></o:p></p>
<p class="MsoNormal">According to strace, it executes a recvfrom which returns ECONNRESET:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">recvfrom(...) = -1 ECONNRESET (Connection reset by peer)<o:p></o:p></span></p>
<p class="MsoNormal">I also straced the Erlang beam process and it indeed gets an ECONNRESET result for the recvfrom call, but the Erlang return value is {error,closed}.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Unfortunately it looks like I really need to separate these two results.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I also tried gen_tcp in active mode, but no difference, the result is {error,closed} instead of {error,econnreset}.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Can someone explain why the econnreset error is masked? Is there any way I can separate the two kinds of events?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><span style=font-size:10.0pt;font-family:"Arial","sans-serif";color:black>Andras G. Bekes <br />
</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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