reasonablekeith has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to push some files around using a couple of perl scripts and sockets, but have come up against an intermittent problem reading and writing data. Simply, my server is doing a syswrite, but my client's sysread doesn't receive all the data.

The sockets are created in the normal way

my $sock = IO::Socket::INET->new(PeerAddr => '', PeerPort => '9090', Proto => 'tcp') or die("Couldn't connect: $!");
my $server = IO::Socket::INET->new( Proto => 'tcp', LocalPort => $PORT, Listen => 10, Reuse => 0) or die("$!");
and my read / write functions look like this
# server sub write { my ($self, $string) = @_; my $server_socket = $self->{SERVER_SOCKET}; my $write_length = sprintf "%020d", length($string); syswrite $server_socket, $write_length, 20; print "Writing $write_length bits of data\n"; syswrite $server_socket, $string, $write_length; } # client sub read { my ($self, $param) = @_; my $sock = $self->get_socket(); my $read_length; my $buffer; sysread $sock, $read_length, 20; sysread $sock, $buffer, $read_length; my $buffer_length = length($buffer); $buffer_length == $read_length or die("Tried to read $read_length bits but only got $buffer_len +gth bits\n"); return $buffer; }
Which occasionally gives output like this.
server ... Writing 00000000000000014848 bits of data client Tried to read 00000000000000014848 bits but only got 13140 bits
The really weird thing is that most times this will just work. My client and server are running on the same machine, which has active perl 5.10, and IO::Socket::INET is at version 1.31.

Ignoring the code and it's limitations (which I'll work on if I get this sorted), does anyone see why this might be failing every now and then?



my name's not Keith, and I'm not reasonable.