<div dir="ltr">I hear you :).<br><br>When I've got some time I will try out my R12B-3 installation on SP4 with your program, but can't right now. I am interested to see what happens.<br><br>Rgds,<br>Ed<br><br><div class="gmail_quote">
On Fri, Sep 12, 2008 at 2:47 PM, Michael Regen <span dir="ltr"><<a href="mailto:michael.regen@gmail.com">michael.regen@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div dir="ltr">Just tested it on another machine with SP3 installed. No difference. Same problem.<br><br>Yes, Windows is flaky and I personally would like to be able to say I would rather go to hell than installing a server on Windows which is expected to run robust.<br>
But well, either Erlang is robust on Windows as well or no Erlang on Windows. :(<br><br>Regards,<br>Michael<br><font color="#888888"><br>-- <br>Quote from a >3000 employees IT centric company's CIO I had the pleasure to witness four weeks ago: 'For the messaging back end? No, we can't use Java. Java is too slow.'</font><div>
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<br><br><br><div class="gmail_quote">On Fri, Sep 12, 2008 at 7:54 PM, Edwin Fine <span dir="ltr"><<a href="mailto:erlang-questions_efine@usa.net" target="_blank">erlang-questions_efine@usa.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div dir="ltr">Michael,<br><br>I've always felt that the Windows version of Erlang is a bit flaky. Then again, I think Windows itself is more than a bit flaky, so maybe it's not Erlang's fault ;)<br>I wonder if running on SP4 would improve things?<div>
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<br><div class="gmail_quote">On Fri, Sep 12, 2008 at 1:39 PM, Michael Regen <span dir="ltr"><<a href="mailto:michael.regen@gmail.com" target="_blank">michael.regen@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div dir="ltr">Hi Edwin,<br><br>It is possible that both issues have a similar source but I do not see many reasons why there must be a common source.<br>I was running my tests on a 32bit single core Windows XP SP2 system just by running<br>
werl.exe -boot start_sasl<br>or<br> werl.exe<br><br>and did nothing fancy. My R12B-3 version is self compiled, R12B-4 is out of the <a href="http://erlang.org" target="_blank">erlang.org</a> box.<br>Client and server tests where done by starting two different instances of werl.<br>
Furthermore my tcp_test:test does not care whether results from gen_tcp:connect are correct or not. It just assumes {ok, Socket} and crashes the process if otherwise. Of course it was a surprise that under some circumstances the whole emulator crashes.<br>
<br>By the way, the crash dump slogan is unspectecular: 'Slogan: Inconsistent, why isnt io reported?'<br><br>UPDATE: I got some more observations which puzzle me even more:<br><br>Just did some more of the same tests but this time by starting:<br>
erl.exe<br> application:start(tcp_server).<br>and<br> erl.exe<br> tcp_test:test(1000).<br><br>There seems to be a difference between erl.exe and werl.exe.<br><br>This time results are pretty different:<br>Now it is much harder to crash the emulator. It takes significant more processes / tries until something bad happens:<br>
<br>client only (tcp_test:test(5000)) crashes eventually in the same way but Window's cmd.exe now follows with a:<br> The exception unknown software exception (0x40000015) occured in the application at location 0x008fff86<br>
<br>after the 'Crash dump was written to: erl_crash.dump / Inconsistent, why isnt io reported?' message and the crash dump file.<br><br>The exception seems to always occure at the same location.<br><br>A lot more error messages are printed now (as expected) until the crash.<br>
Besides the {{badmatch,{error,econnrefused}},[{tcp_test,test_con,0}]} I can now also watch lots of<br> {{badmatch,{error,eaddrinuse}},[{tcp_test,test_con,0}]}<br>and<br> {{badmatch,{error,system_limit}},[{tcp_test,test_con,0}]}<br>
errors.<br><br>The good message: During tests together with the server backend I was not able to crash the server. But I am not convinced that erl.exe solves everthing server side.<br><br>Regards,<br><font color="#888888">Michael</font><div>
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On Fri, Sep 12, 2008 at 6:32 PM, Edwin Fine <span dir="ltr"><<a href="mailto:emofine@gmail.com" target="_blank">emofine@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div dir="ltr">Please be aware that I reported a bug a while ago on erlang-bugs, where attempting to connect to a socket that is not being listened on will sometimes return an actual success return, but subsequent operations will fail. Here is an excerpt from that bug report.<br>
<br><pre>When calling gen_tcp:connect/3 or /4 on a host/port that does not have a<br>running program listening on it, at random intervals gen_tcp:connect returns<br>an {ok, Sock} instead of the expected {error, econnrefused}. If<br>
gen_tcp:recv(Sock, 0) is called immediately using the socket just returned,<br>it returns an {error, econnrefused}. Connection options used were [binary,<br>{packet, raw}, {active, false}]. It should be noted that the gen_tcp:connect<br>
succeeds when there is a program listening on that sane host/port, so it's<br>unlikely to be a firewall issue.<br></pre>See <a href="http://www.erlang.org/pipermail/erlang-bugs/2008-August/000931.html" target="_blank">http://www.erlang.org/pipermail/erlang-bugs/2008-August/000931.html</a><br>
<br>This bug is still present in R12B-4. Could this be affecting you?<br><br>Regards,<br>Edwin Fine<br><br><div class="gmail_quote">2008/9/12 Michael Regen <span dir="ltr"><<a href="mailto:michael.regen@gmail.com" target="_blank">michael.regen@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div></div><div><div dir="ltr">Hi,<br><br>I got a series of troubles with gen_tcp all eventually resulting in crashes. I tested this under Windows XP and with R12B-3 as well as R12B-4. Under Linux it seems to work but I am not perfectly sure since the crash happens sporadically and seems to be timing related.<br>
<br>The two problems below lead me to a couple of questions:<br>a) What is the real cause? Is it the socket error enfile? Do both problems have the same root cause?<br>b) Is there a bug in Erlang? I guess this should not lead to a crash.<br>
c) How do you avoid this problem on systems you do not control yourself?<br><br><br>Problem #1:<br>###########<br><br>Just compile the following code and run it with sasl enabled and the following command:<br> tcp_test:test(1000).<br>
and - yes - without anything listening on port 2222. And sometimes you have to try two times!<br><br>-------------------------- start: tcp_test.erl --------------------------<br>-module(tcp_test).<br><br>-export([test/1, test_con/0]).<br>
<br>-define(DEF_PORT, 2222).<br>-define(DEF_IP, {127,0,0,1}).<br><br>test(0) -> ok;<br>test(HowManyProcs) -><br> spawn(?MODULE, test_con, []),<br> test(HowManyProcs-1).<br><br>test_con() -><br> {ok,S} = gen_tcp:connect(?DEF_IP, ?DEF_PORT,[]),<br>
gen_tcp:send(S,<<0,5,65,66,67,68,69>>),<br> receive<br> {tcp_closed, _Socket} -> ok;<br> _Msg -> gen_tcp:close(S)<br> after 500 -><br> gen_tcp:close(S)<br> end.<br>-------------------------- end: tcp_test.erl --------------------------<br>
<br>It just spawns a bunch of processes all trying to connect to a currently closed port and sending some garbage there. This is what happens:<br><br>-------------------------- start: log tcp_test.erl --------------------------<br>
=ERROR REPORT==== 12-Sep-2008::15:28:47 ===<br>Error in process <0.41.0> with exit value: {{badmatch,{error,econnrefused}},[{tcp_test,test_con,0}]}<br><br>[... a couple of them but usually between 1 and 20.]<br><br>
=ERROR REPORT==== 12-Sep-2008::15:28:47 ===<br>Error in process <0.103.0> with exit value: {{badmatch,{error,econnrefused}},[{tcp_test,test_con,0}]}<br><br><br>Crash dump was written to: erl_crash.dump<br>Inconsistent, why isnt io reported?<br>
<br>Abnormal termination<br>-------------------------- end: log tcp_test.erl --------------------------<br><br>It might have something to do with the socket error enfile 'file table overflow' but I guess it should not simply crash the emulator!?<br>
Searching google for 'Inconsistent, why isnt io reported?' just gives one hit to Erlang's source code.<br>I can provide the crash dump if needed. Just did not want to spam the whole list with big attachments.<br>
Spawning only 500 processes (tcp_test:test(500).) usually leads to a crash, spawning only 200 seems to work.<br><br><br>Problem #2:<br>###########<br><br>Now let's try the same with a server answering to port 2222: Just take the code from the trapexit tutorial 'Building a Non-blocking TCP server using OTP principles' <a href="http://trapexit.org/Building_a_Non-blocking_TCP_server_using_OTP_principles" target="_blank">http://trapexit.org/Building_a_Non-blocking_TCP_server_using_OTP_principles</a><br>
Start it first and then our test module in a different erlang node as described above. Now, usually the client survives (have seen crashes as well!) and the server crashes in a similar way. Sometimes it survives and in very rare cases you will see the following logs in the erlang server instance:<br>
<br>-------------------------- start: log server --------------------------<br>=ERROR REPORT==== 12-Sep-2008::12:58:56 ===<br>File operation error: system_limit. Function: get_cwd. Process: code_server.<br><br>=ERROR REPORT==== 12-Sep-2008::12:58:56 ===<br>
Error in async accept: {async_accept,"file table overflow"}.<br><br>=ERROR REPORT==== 12-Sep-2008::12:58:56 ===<br>** Generic server tcp_listener terminating <br>** Last message in was {inet_async,#Port<0.109>,1019,{ok,#Port<0.2141>}}<br>
** When Server state == {state,#Port<0.109>,1019,tcp_echo_fsm}<br>** Reason for termination == <br>** {async_accept,"file table overflow"}<br><br>[...]<br>-------------------------- end: log server --------------------------<br>
<br>Can anyone help? Thank you!<br><br>Regards,<br>Michael<br></div>
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