connect(2)/accept(2) oddity

Richard.Gooch@atnf.csiro.au
Sat, 27 Jun 1998 17:20:59 +1000


Hi, all. I've come across what appears to be some strange behaviour
in the Linux connect(2) and accept(2) implementation. I have a server
that basically does:

sock = socket ();
bind (sock);
listen (sock);
poll (all my FDs);
IF input ready on sock, newfd = accept (sock), ++conn_count;
IF first time input ready on a newfd, print conn_count;

And my client does this:
DO 1000 times
fd[i] = connect ();
write (fd[999]);

Now what is happening is that the server is printing conn_count before
it reaches 1000. The client is run on my dual-PPro. If I run the
server also on my dual PPro (and use Unix sockets), conn_count = 900+
when it prints. If I run the server on a P100, conn_count = 300+.

If I have the server write a byte right after accept(2) and the client
reads it before doing the next connect(2), then conn_count is always
printed when it is 1000.

This seems strange to me. It appears connect(2) is returning before
the accept(2) completes. Am I missing something here, or is Linux
behaving strangely?

Regards,

Richard....

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