Date: Fri, 18 Feb 2005 16:18:41 +0300 From: Deomid Ryabkov <myself@rojer.pp.ru> To: freebsd-hackers@freebsd.org Subject: occasional ECONNREFUSED when connect()ing. Message-ID: <4215EB31.8020107@rojer.pp.ru>
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[-- Attachment #1 --] I have a strange case of occasional refused connect()'s. The system is running 4.10-STABLE. This was originally reported by one of our developers. The test script he provided is a simple Perl script that repeatedly fetches an URL from Apache running on this same server. In the run of 2000 iterations, there are 5-10 random errors fetching the URL. After further investigation and digging, I uncovered the true cause of the error: connect() returning ECONNREFUSED. To see if this was somehow related to Apache, I wrote my own simple server that accept()'s a connection, read()'s what supposed to be request and write()'s a stereotypic reply, thus resembling an HTTP request/reply conversation. The number of sporadically occuring connect() errors has increased somewhat, maybe due to quicker turnaround of my stub-server. The question is - why do connections get refused at all? I can think of no valid reasons... here's the output of the client as i see it: ----------------------------- sample output of x.pl ----------------------------- 71590, http://localhost:8000/junk, 2000: starting. 59 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 127 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 213 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 259 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 363 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 402 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 416 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 690 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 703 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 754 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 947 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 960 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 997 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 1163 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 1272 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 1433 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 1612 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) 1887 500 Can't connect to localhost:8000 (Timeout connect: Connection refused) ----------------------------- cut ----------------------------- (the confusing "Timeout connect:" message is a result of my IO/Socket/INET.pm hacking. without it, just a confusing "Timeout" was reported. i added printing of actual error string.) a fragment of output of the same script running under strace: ----------------------------- strace of x.pl ----------------------------- socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 3 fcntl(3, F_GETFL) = 0x2 (flags O_RDWR) fcntl(3, F_GETFL) = 0x2 (flags O_RDWR) fcntl(3, F_SETFD, FD_CLOEXEC) = 0 fcntl(3, F_GETFL) = 0x2 (flags O_RDWR) fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_INET, sin_port=htons(8000), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 ECONNREFUSED (Connection refused) ----------------------------- cut ----------------------------- and the source of both server and client used: ----------------------------- accepter.c (server) ----------------------------- #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <stdio.h> char *reply = "HTTP/1.0 200 OK\r\nConetnt-type: text/plain\r\n\r\nNothing special.\r\n"; int rlen; int main(int argc, char **argv) { int i, cal; int s, ss, n; char *buf; struct sockaddr_in saddr, caddr; memset(&saddr, 0, sizeof saddr); saddr.sin_family = AF_INET; saddr.sin_addr.s_addr = htonl(INADDR_ANY); saddr.sin_port = htons(8000); ss = socket(PF_INET, SOCK_STREAM, 6); if (ss < 0) return 1; if (bind(ss, (struct sockaddr *) &saddr, sizeof saddr) < 0) return 2; if (listen(ss, 511) < 0) return 3; buf = (char *) malloc(4096); if (buf == NULL) return 4; rlen = strlen(reply); fprintf(stderr, "accepting.\n"); for (cal = sizeof caddr; s = accept(ss, (struct sockaddr *) &caddr, &cal); cal = sizeof caddr) { n = read(s, buf, 4096); if (n > 0) { write(s, reply, rlen); } close(s); } return (s < 0); } ----------------------------- cut ----------------------------- ----------------------------- x.pl (client) ----------------------------- #!/usr/bin/perl $| = 1; use LWP::UserAgent; $url = 'http://localhost:8000/junk'; my $n = 2000; print "$$, $url, $n: starting.\n"; for (my $i = 0; $i < $n; $i++) { my $ua = LWP::UserAgent->new; $ua->timeout(1000); $req = HTTP::Request->new("GET" => $url); $res = $ua->request($req); print $i." ".$res->status_line."\n" if (0 or $res->code == 500); } exit(); ----------------------------- cut ----------------------------- -- Deomid Ryabkov aka Rojer myself@rojer.pp.ru rojer@sysadmins.ru ICQ: 8025844 [-- Attachment #2 --] 0 *H 01 0 + 0 *H #00U v0 *H 0b1 0 UZA1%0#U Thawte Consulting (Pty) Ltd.1,0*U#Thawte Personal Freemail Issuing CA0 040331221809Z 050331221809Z0_10URyabkov10 U*Deomid10UDeomid Ryabkov1!0 *H myself@rojer.pp.ru0"0 *H 0 x?ed:4y h"0 $F;O 4{ 7kU-)A { ;qrk,6s+ZȀ&Qvi)ZRu%0 @<r \=/)NK4풓d|$_&aNq!ڨ 66.ʺ`WPFmd;,H,ؑPd0!J5Sـd PIK3@]42g \i3 /0-0 U 0myself@rojer.pp.ru0 U 0 0 *H + ~ 4YXf DW?%\;҇B2n Ϸ|Jճ2++fZ7[m~X㽀c6x*2%^ LnmoUkQ|Z>?X\uɝp/:00U v0 *H 0b1 0 UZA1%0#U Thawte Consulting (Pty) Ltd.1,0*U#Thawte Personal Freemail Issuing CA0 040331221809Z 050331221809Z0_10URyabkov10 U*Deomid10UDeomid Ryabkov1!0 *H myself@rojer.pp.ru0"0 *H 0 x?ed:4y h"0 $F;O 4{ 7kU-)A { ;qrk,6s+ZȀ&Qvi)ZRu%0 @<r \=/)NK4풓d|$_&aNq!ڨ 66.ʺ`WPFmd;,H,ؑPd0!J5Sـd PIK3@]42g \i3 /0-0 U 0myself@rojer.pp.ru0 U 0 0 *H + ~ 4YXf DW?%\;҇B2n Ϸ|Jճ2++fZ7[m~X㽀c6x*2%^ LnmoUkQ|Z>?X\uɝp/:0?0 0 *H 01 0 UZA10U Western Cape10U Cape Town10U Thawte Consulting1(0&U Certification Services Division1$0"UThawte Personal Freemail CA1+0) *H personal-freemail@thawte.com0 030717000000Z 130716235959Z0b1 0 UZA1%0#U Thawte Consulting (Pty) Ltd.1,0*U#Thawte Personal Freemail Issuing CA00 *H 0 Ħ<UsUNʙZ hup [v :aQP 0cZ,p+Z?qV˯< 6$*+w=+>@dקe*TH<a@ dr` 00U 0 0CU <0:08642http://crl.thawte.com/ThawtePersonalFreemailCA.crl0 U 0)U "0 0 10UPrivateLabel2-1380 *H HP . fgCL!6 -6/ P p<ab:~ t%Pb'qW%ݩ9 Oe_N4[5MwV!x!5$ F]_eO1;070i0b1 0 UZA1%0#U Thawte Consulting (Pty) Ltd.1,0*U#Thawte Personal Freemail Issuing CA v0 + 0 *H 1 *H 0 *H 1 050218131841Z0# *H 1'^d.3?/z2E@0R *H 1E0C0 *H 0*H 0 *H @0+0 *H (0x +71k0i0b1 0 UZA1%0#U Thawte Consulting (Pty) Ltd.1,0*U#Thawte Personal Freemail Issuing CA v0z *H 1ki0b1 0 UZA1%0#U Thawte Consulting (Pty) Ltd.1,0*U#Thawte Personal Freemail Issuing CA v0 *H RC2!| oQ9 Peg Y0jzm$0 0SD$5#SE/Vy}wc%D-˭"&J2'gXXfv (6ޭ̤ LѶ'5϶3gkr*` }U*s1QHJ:p5<Ru6bEVMjNO*! t^R0>MBc/ mڙ驋'bsQ,~$xWnWZ vj
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