On Mon, Dec 7, 2009 at 1:18 AM, André Warnier <a...@ice-sa.com> wrote:
> Bill Moseley wrote: > >> >> Again, I've got keep alives set for a long time. >> > > Well, isn't that your problem then ? > KeepAlive connections were introduced at a time when establishing and > tearing down TCP connections were relatively expensive things to do. > With modern servers however, this is less important. > > By setting KeepAliveTimeOut long, you essentially "block" a child (and all > its resources), doing nothing but waiting for a follow-up request, for a > long time after the last related request from the browser has come in, for > the dubious benefit of avoiding the setup of a new connection. > This is true for my test environment I described, but that was just for testing and was on purpose. Under production a load balancer is used between the client and the Apache/mod_perl servers. It works as a proxy where the connection to the client is separate from the connection to the pool of backend processes on each server. The balancer manages this pool of persistent connections ready to handle requests. Clients make separate persistent connections on the front of the balancer, too. But these are not directly connected to any one process. Requests come in from the presistent clients and the balancer finds a free backend process to handle the request. The backend services the request very quickly and then is available to service other requests while the client receives its response. The keep-alive timeouts are different on both sides of the balancer. If the balancer maintains persistent connections to the back-end processes then the problem is how to gracefully shut down a server. Just doing a graceful stop won't work because the connections keeps the process alive. One way is to pull the server from the balancer pool, wait for existing requests to finish (only a few seconds) and then stop the server. Problem there is that it's not always the same people running the web servers and balancers. So, it would be more convenient if a graceful restart could be done on just Apache and that would trigger closing the connections on the next response freeing up the process to exit. That's the part I'm trying to get working. -- Bill Moseley mose...@hank.org
