Let me please add another important (I think) bit of information. In
my previous mail I reported that a call to fork() is essential to
reproduce the weird read()/write() problem. It turns out that only the
child is affected. If I modify the server to let the parent answer the
client request after forking, everything is fine again. This should
IMHO rule out any timing related issues.
A small change to server program will do the trick:
------------------------------------------------------
--- server5b.c Fri Dec 8 16:49:27 2000
+++ server5c.c Fri Dec 8 21:55:46 2000
@@ -52,22 +52,22 @@
printf("adding client on fd %d\n", client_sockfd);
}
else {
- if (fork() == 0) { /* child */
+ if (fork() != 0) { /* parent */
iread(fd, ch, 10);
sleep(1);
- printf("child serving client on fd %d; ch=%s<<\n", fd, ch);
+ printf("parent serving client on fd %d; ch=%s<<\n", fd, ch);
ch[0]++;
iwrite(fd, ch, 5);
iwrite(fd, ch+5, 5);
close(fd);
FD_CLR(fd, &readfds);
- printf("child done on fd %d; ch=%s<<\n", fd, ch);
- exit(0);
+ printf("parent done on fd %d; ch=%s<<\n", fd, ch);
}
- else { /* parent */
+ else { /* child */
close(fd);
FD_CLR(fd, &readfds);
- printf("parent done on fd %d\n", fd);
+ printf("child done on fd %d\n", fd);
+ exit(0);
}
}
}
------------------------------------------------------
So my (un)educated guess is that it is less a read()/write() problem
per se but rather a problem how an inherited socket is set up in the
child process after forking.
regards,
Markus
--
Markus Hoenicka, PhD
UT Houston Medical School
Dept. of Integrative Biology and Pharmacology
6431 Fannin MSB4.114
Houston, TX 77030
(713) 500-6313, -7477
(713) 500-7444 (fax)
[EMAIL PROTECTED]
http://ourworld.compuserve.com/homepages/hoenicka_markus/
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