Dear Monks, I have created a simple client and server program which will just consecutively write and read data from a single socket connection. I have enabled non blocking socket using ioctl to ensure that in case i dont get anything to read from the socket then sysread will not wait there indefinitely. If ioctl is disabled then i am able to send and receive the appropriate data on both the client and server. With ioctl enabled i am not able to receive the data on the client side consistently though the sysread no longer blocks when there is no data to read. I have done 2 syswrites and 2 sysreads on both the client and server sides. On the client side i find that sometimes i get the data of the first sysread operation when i do the second sysread. The same problem happens with sysread on the server side as well. It looks like the socket buffer is not getting flushed. I have tried a number of methods to flush the buffer including autoflush, flush, $| and print LOG "". In all cases still i find that the buffer does not get properly flushed and that the problem persists. I am new to socket programming in Perl. Please help.

use IO::Socket; 

#To flush the buffer print statements
$| = 1;  

my $sock = new IO::Socket::INET( PeerAddr => 'localhost', PeerPort => 
+7890, Proto => 'tcp'); 

if ($sock) 
{
   print "A tcp socket on localhost connected to 7890\n";
} 
else 
{
   die "Error: $!"; 
}
$nonblocking = 1;
ioctl($sock, 0x8004667e, \$nonblocking);
$buf = "1234567890";
syswrite($sock, $buf, 10);
sysread($sock, $buf, 10);
$sock->flush;
print "Bytes 10 = $buf\n";
syswrite($sock, "1", 1);
print "\n";
$sock->flush;
sysread($sock, $buf, 2);
print "Bytes 2 = $buf\n";
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use IO::Socket; 

$| = 1;
         
my $sock = new IO::Socket::INET( 
LocalHost => "localhost", 
LocalPort => 7890, 
Proto => "tcp", 
Listen => SOMAXCONN, 
Reuse => 1,
Timeout => 20
); 

if ($sock) {
   print "A $Proto socket created on $LocalHost listening on $LocalPor
+t\n";
} else {
   die "Error - no listening socket created : $!"; 
}
$flush = 1;
while (($new_sock,$c_addr) = $sock->accept()) {
my ($client_port, $c_ip) = sockaddr_in($c_addr); 
my $client_ipnum = inet_ntoa($c_ip); 
my $client_host =gethostbyaddr($c_ip, AF_INET); 
print "Got a connection from: $client_host"," [$client_ipnum] \n"; 
print "Created new socket for reading or writing data to Client\n";

$nonblocking = 1;
ioctl($new_sock, 0x8004667e, \$nonblocking);

sysread($new_sock, $buf, 10);
print "$buf\n";
syswrite($new_sock, $buf, 10);
$new_sock->flush;
sysread($new_sock, $buf, 1);
print "$buf\n";
$new_sock->flush;
syswrite($new_sock, "12", 2);
}
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