I have an annoying socket related problem.
After a lot of trial and error I have found a work-around to the problem and my code is now functional.
On the other hand, I don't understand why my work-around works, neither why it is required. This is where your help and explanations will be much appreciated.
Scenario:
I have a 'server' application that opens a socket. It then loops around an
accept() on the socket. Whenever a client connects, the server reads and (for testing purposes only) discards anything read. It
never writes anything to the socket. This part works fine.
I have a test client that does nothing but connect to the server socket and then closes the socket. It writes nothing to the socket before closing it.
This creates
a major memory leak in the client application.
If I let the client write some arbitrary text to the socket, the problem remains. But, if I let the client
read from the socket, the memory leak goes away (?!?!). There was nothing there to read. The client immediately gets a logical end-of-file, but it will not leak memory.
Question:
How can this be?
Code:
This is a code snippet that reproduces the problem:
#!/usr/bin/perl -w
require 5.005;
use strict;
use IO::Socket;
for(1..100000) {
open_sock();
}
exit;
sub open_sock {
my $answer;
my $sock=IO::Socket::INET->new(PeerAddr=>'10.118.32.31',
PeerPort=>1955,
Proto=>'tcp',
Timeout=>20)||
die("Failed to open socket.\n");
# Writing to the socket makes no difference.
#print $sock "x";
# Reading from the socket closes the memory leak.
# Nothing gets printed on STDOUT from the print statement,
# i.e. there was nothing to read. Right?
while(defined($answer=<$sock>)) {
print("Answer: $answer\n");
}
close($sock);
}
Environment:
- Windows NT V4.00.1381
- ActiveState Perl V5.6.0, build 616 (Yes, it's out of date, but I can't upgrade the production server for another good while. Probably when 5.8 is released.)
Everything went worng, just as foreseen.
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