According to Greg Stark:
> > > 1) Netscape/IE won't intermix slow dynamic requests with fast static requests
> > > on the same keep-alive connection
> >
> > I thought they just opened several connections in parallel without regard
> > for the type of content.
>
> Right, that's the problem. If the two types of content are coming from the
> same proxy server (as far as NS/IE is concerned) then they will intermix the
> requests and the slow page could hold up several images queued behind it. I
> actually suspect IE5 is cleverer about this, but you still know more than it
> does.
They have a maximum number of connections they will open at once
but I don't think there is any concept of queueing involved.
> > > 2) static images won't be delayed when the proxy gets bogged down waiting on
> > > the backend dynamic server.
>
> Picture the following situation: The dynamic server normally generates pages
> in about 500ms or about 2/s; the mod_perl server runs 10 processes so it can
> handle 20 connections per second. The mod_proxy runs 200 processes and it
> handles static requests very quickly, so it can handle some huge number of
> static requests, but it can still only handle 20 proxied requests per second.
>
> Now something happens to your mod_perl server and it starts taking 2s to
> generate pages.
The 'something happens' is the part I don't understand. On a unix
server, nothing one httpd process does should affect another
one's ability to serve up a static file quickly, mod_perl or
not. (Well, almost anyway).
> The proxy server continues to get up to 20 requests per second
> for proxied pages, for each request it tries to connect to the mod_perl
> server. The mod_perl server can now only handle 5 requests per second though.
> So the proxy server processes quickly end up waiting in the backlog queue.
If you are using squid or a caching proxy, those static requests
would not be passed to the backend most of the time anyway.
> Now *all* the mod_proxy processes are in "R" state and handling proxied
> requests. The result is that the static images -- which under normal
> conditions are handled quicly -- become delayed until a proxy process is
> available to handle the request. Eventually the backlog queue will fill up and
> the proxy server will hand out errors.
But only if it doesn't cache or know how to serve static content itself.
> Use a separate hostname for your pictures, it's a pain on the html authors but
> it's worth it in the long run.
That depends on what happens in the long run. If your domain name or
vhost changes, all of those non-relative links will have to be
fixed again.
Les Mikesell
[EMAIL PROTECTED]
