Keeping HTTP sessions alive

[Anonymous Monk]

G'Day Monks,

I'm working on a script to do some server testing. I need to go grab some webpages off of the server with LWP::UserAgent. Here's the trick though: I need to keep the HTTP connections open. So, after I fetch the page, I would like to keep the HTTP session open for some arbitrary amount of time afterward. Is this possible? The server does support KeepAlive, if that helps, but I find that doing this:

my $ua = LWP::UserAgent->new(keep_alive => undef);
my $req = HTTP::Request->new(GET => $url);
my $res = $ua->request($req);

simply fetches the webpage and doesn't keep the connection alive once it's done. Note that I used undef because according to CPAN documentation, that value is passed on to LWP::ConnCache as total_capacity. The LWP::ConnCache documentation says that if total_capacity is set to undef, the total capacity is unlimited.

If it's not possible to keep a connection alive after fetching a page, is it possible to simply open a connection and keep it alive (without ever fetching a page) instead?

[davido]

A quick search using SuperSearch for the term "keep_alive" turned up just a few threads... not a lot. I see that in this thread liz commented that not all HTTP servers support the keep_alive option. Are you sure yours does?

Also, most of the examples I find set keep_alive to 1, not undef.

Update: Looking into the Apache Webserver source provides some interesting information. At the following link you'll be able to look at just what is required before a connection can be kept alive: http://lxr.webperf.org/source.cgi/modules/http/http_protocol.c#206

The important part starts around line 206:

Read more... (2 kB)
It appears that a number of criteria must be met for it to be possible to keep a session alive.

Based on the above link, I would suggest checking the following:

• Is your server configured to enable keep_alive?
• Are you outputting HTTP v1.1 style requests?
• Are you a buggy twit? (sorry, couldn't resist.. I have no idea what they mean by that)
• Have the max number of connections been reached?
• Have you set a resonable inter-request timeout?

Hopefully that's enough to get you started.

[IlyaM]

Add use LWP::Debug qw(+); and check debug output. It may tell why LWP::UserAgent and server you are testing doesn't keep connections opened.