Michael Curtis <[EMAIL PROTECTED]> writes:
> Hello, I have a LWP application that POSTs thousands of small files to
> a mod_perl server. All POSTs *under* a certain size (around 3k) seem
> to take about 200x as long as those over. In this case about 0.09
> seconds as opposed to 0.004 seconds.
>
> After much debugging I narrowed the issue down to TCP latency and
> discovered I can get around the problem by setting TCP_NODELAY on the
> socket.
>
> My workaround is redefining the LWP::Protocol::http::_check_sock()
> method and adding a setsockopt($sock, 6, 1, pack("l", 1)). This tweak
> significantly improves performance on small POSTs but feels like a
> total hack.
>
> Can I be sure that the _check_sock() method will always be there? The
> function itself doesn't do anything so I assume its just a hook. Is
> there another, better way to do this? Thanks much.
This message was written in July, so I'm sorry about the long delay
before answering it. I still hope some might find the example code
below useful.
The _check_sock hook will always be there, as it's part of the
(undocumented) subclassing API. It is for instance overridden by the
LWP::Protocol::https module. Just redefining the function is a hack
and might disable code if the default _check_sock() would start do
something in the future, so I don't recommend that approach.
This is how I would suggest you do it by subclassing the protocol
handler:
#!perl -w
use strict;
use LWP::UserAgent;
{
package MyHTTP;
use base 'LWP::Protocol::http';
LWP::Protocol::implementor(http => __PACKAGE__);
package MyHTTP::Socket;
use base 'LWP::Protocol::http::Socket';
use Socket qw(IPPROTO_TCP TCP_NODELAY);
sub new {
my $class = shift;
my $sock = $class->SUPER::new(@_);
if ($sock) {
setsockopt($sock, IPPROTO_TCP, TCP_NODELAY, 1);
}
return $sock;
}
}
# test it
my $ua = LWP::UserAgent->new;
my $res = $ua->post("http://example.com";, [foo => 1]);
print $res->as_string;
The MyHTTP class just subclass from LWP::Protocol::http and register
itself as the one to handle 'http' requests for LWP. MyHTTP will as a
subclass of LWP::Protocol::http by default create sockets of the class
'MyHTTP::Socket' and we also provide this class and override its
constructor to set the socket options we want after the socket is
created.
Regards,
Gisle
