Joerg Sonnenberger wrote:
Only if you use a broken web server. With a proper O(1) event
notification mechanism and async web servers, keep-alive is a huge win,
if you don't have a single server load high enough to run out of file
descriptors.
Heh... well:
- We only recently got proper O(1) event notifications,
- We definitely don't have an asynchronous server, and
- During the peak, our onlines run pretty darn close to full capacity.
To expand on the second point a bit: when you make a request to our
server, that thread is tied up for the duration of your request. Each
server has a fixed number of threads, so tying one of these up to handle
keep-alive would be a big deal. Our way of gracefully handling a
request which holds the thread too long is to just kill it (and log tons
of errors and page a few engineers). Yeah, ugly.
Even if we were to fix the thread issue, there's enough custom legacy
crap which assumes a request-per-thread model that lots of stuff would
break. I'd like to think we're unique in being this crufty, but the
anecdotal tales I hear lead me to believe this is about par... :-(
