1. First of all the timeout value is absolutely not only for socket creation, or accept, but for 'various' operations as stated in doc for IO::Socket::INET, so it is also for things like read/write/send/recv, which are behind your get/put from a Net::FTP view.
2. The purpose of timeout is to leave space for retry and recovery. You said that you set timeout to 120 seconds, you pulled out the cable in middle of get operation, and the get operation timed out after 120 seconds from the moment you pulled out the cable. That's exactly what you should expect. If it is counted from the beginning of the operation, it does not make any sense. For example, you set timeout to 120 seconds, you start getting a huge file, at the 130th second, you pull out the cable, if timeout is counted from the beginning of the get operation, then it will timeout right away, there is no space for retry or whatsoever. this is not what you want, right?
3. You also did another test, in which you pluged the cable back before timeout, and the transfer is successful. I believe you already know the reason. Yes, you are right, that's the space for retry/recovery, and the recovery was successful before the timeout.

Thanks for the update, I feel a serene sense of enlightenment! =')

I'm also going to check out that 'rsync' utility that others have pointed out. (thanks guys!)


-Carlos

Timeout is the amount of time you want to give the command to work. If it hits the limit, it dies

It has a purpose if you know something should not take long. For example an FTP to a local server versus one of a slow wan link. You would increase the timeout for the slow wan and most likely decrease for the local server

If you want more network programming, take a look a Lincoln Steins "Network Programming with Perl"

To hopefully add a bit of clarity. I have the stein book in front me, which is a must read to say the least. The timeout is a timeout on the socket operation itself. Which means, it will attempt to create a socket to the host you specify BUT if a socket is not created in 120 seconds then the operation itself will time out and the operation will return an error.

Hopefully you are catching such an error e.g.

my $ftp = Net::FTP->new(HOST) or die "Can't connect: $@\n";

and if you want to you can get the client to retry it's connection based on that error. The other thing to think about is if you are getting these errors often you might want to grab a network sniffer to determine if your network links are being overloaded or if the server is getting overloaded with connections and is becoming slower to respond.

In either case you might want to set the clients to connect in groups by time to prevent a small scale denial of service attack on your server, I don't know how many clients you have, and from consuming all possible bandwith.

Hope this helps!,
Dave -- Saving the world one node at a time

Thanks for your reply. I have a question in reference to your first paragraph regarding the nature of socket creation: Is a socket created only uppon connection, or is it done continually throughout the connection?

I ran a little test where I began a connection, and started a file transfer:

$ftp_a = Net::FTP->new($remhostname, Timeout => 120, 
                                     Debug   => 1)
|| &error && die "Cant connect to $remhostname\n";
$ftp_a->login ($remusername,$rempassword)
|| &error && die "Cant login to $remhostname\n";
$ftp_a->binary (); 
$ftp_a->cwd ("$home\/$fpath")
|| warn "Cant find Directory $home/$fpath\n";
$ftp_a->get("$fname")
or &error && die $ftp_a->message;
$ftp_a->quit;
[download]

After the file transfer had begun, I disconnected the network cable, and watched as the script was terminated at 120 seconds from the time I removed the cable.

I then ran the test again with the Timeout value set to 900. Again, the script terminated at the Timeout value. If the connection was restored at any time within the timout period, the transfer would continue as normal.

I don't have a lot of experience with network programming, but this seems to imply that the timeout is for more than just the connection. However, I still don't know specifically what.


Best Regards,

-Carlos

"If at first you don't succeed, skydiving is not for you!"

I didn't even finish reading your post before I started thinking why aren't you using rsync? Most CPAN mirrors are using rysnc now...

Cheers,

-J