Mod_proxy_balancer is just a weighted round-robin, and doesn't
consider actual worker load, so I don't think this will help you. Have
you looked at Evented Mongrel?
Evan
On 10/15/07, Robert Mela <[EMAIL PROTECTED]> wrote:
> Rails instances themselves are almost always single-threaded, whereas
> Mongrel, and it's acceptor, are multithreaded.
>
> In a situation with long-running Rails pages this presents a problem for
> mod_proxy_balancer.
>
> If num_processors is greater than 1 ( default: 950 ), then Mongrel will
> gladly accept incoming requests and queue them if its rails instance is
> currently busy. So even though there are non-busy mongrel instances,
> a busy one can accept a new request and queue it behind a long-running
> request.
>
> I tried setting num_processors to 1. But it looks like this is less
> than ideal -- I need to dig into mod_proxy_balancer to be sure. But at
> first glance, it appears this replaces queuing problem with a proxy
> error. That's because Mongrel still accepts the incoming request --
> only to close the new socket immediately if Rails is busy.
>
> Once again, I do need to set up a test and see exactly how
> mod_proxy_balancer handles this... but...
>
> If I understand the problem correctly, then one solution might be moving
> lines 721 thru 734 into a loop, possibly in its own method, which does
> sth like this:
>
> def myaccept
> while true
> return @socket.accept if worker_list.length < num_processors ##
> check first to see if we can handle the request. Let client worry about
> connect timeouts.
> while @num_processors < reap_dead_workers
> sleep @loop_throttle
> end
> end
> end
>
>
>
> 720 @acceptor = Thread.new do
> 721 while true
> 722 begin
> * 723 client = @socket.accept
> * 724
> 725 if $tcp_cork_opts
> 726 client.setsockopt(*$tcp_cork_opts) rescue nil
> 727 end
> 728
> 729 worker_list = @workers.list
> 730
> 731 if worker_list.length >= @num_processors
> 732 STDERR.puts "Server overloaded with
> #{worker_list.length} processors ([EMAIL PROTECTED] max).
> Dropping connection."
> * 733 client.close rescue Object*
> 734 reap_dead_workers("max processors")
> 735 else
> 736 thread = Thread.new(client) {|c| process_client(c) }
> 737 thread[:started_on] = Time.now
> 738 @workers.add(thread)
> 739
> 740 sleep @timeout/100 if @timeout > 0
> 741 end
>
>
> _______________________________________________
> Mongrel-users mailing list
> [email protected]
> http://rubyforge.org/mailman/listinfo/mongrel-users
>
>
--
Evan Weaver
Cloudburst, LLC
_______________________________________________
Mongrel-users mailing list
[email protected]
http://rubyforge.org/mailman/listinfo/mongrel-users
