[Mongrel] Unix Domain Sockets + Fork for improved scalability
normalperson at yhbt.net
Thu May 8 03:50:25 EDT 2008
Jeremy Hinegardner <jeremy at hinegardner.org> wrote:
> On Mon, May 05, 2008 at 11:37:56PM -0400, Brian Weaver wrote:
> > Unfortunately a long running request could cause our entire web
> > application to "hang". As these requests are being processing one or
> > more mongrel instances continued to accept and enqueue new connections
> > it can't immediately service.
Heh, this is also the exact problem I designed qrp around, too.
> Another solution:
> You could stick HAproxy in front of your mongrel cluster with a the
> configuration somewhat like:
> listen application *:80
> balance roundrobin
> server mongrel0 127.0.0.1:5000 minconn 1 maxconn 1 check
> server mongrel1 127.0.0.1:5001 minconn 1 maxconn 1 check
> server mongrel2 127.0.0.1:5002 minconn 1 maxconn 1 check
> server mongrel3 127.0.0.1:5003 minconn 1 maxconn 1 check
> server mongrel4 127.0.0.1:5004 minconn 1 maxconn 1 check
> The 'minconn 1 maxconn 1' will force haproxy to queue the results within
> itself instead of mongrel, and the 'check' will take the mongrel out of
> rotation if it goes down, and add it back into the rotation as soon as
> it comes back up. As soon as one mongrel is finished with a request,
> haproxy will give it one of the ones it has queued.
> This is a simple version of what I'm doing to load balance clusters of
> mongrels these days.
I initially tried doing this with haproxy before I made qrp, but it made
monitoring/testing something against an individual backend Mongrel
process far more difficult as I require Mongrel to accept connections
haproxy didn't forward; so I disabled concurrency on the Mongrel
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