Varnish

Varnish and Graphite

Varnish and Graphite

At work we have a reasonably busy Varnish cluster. We hooked it up to Graphite to allow near real-time visualization of how busy it is. Here’s a sample of what part of our Graphite dashboard looks like when you look over the past four months: ![Varnish traffic][3]
Scaling Varnish

Scaling Varnish

As seen on varnish-misc@varnish-cache.org: I read one web testimony of a person who used Varnish to scale a site up to almost 200 million page views a month. I’d like to find someone who has that level of expertise. At work we have a Varnish cluster which, during the month of March, served over 17 billion requests for an average of 6,400 requests/second. This cluster contains two physical machines with 24 cores and 192GB of RAM apiece.
Varnish Expiration Thread Lock Contention

Varnish Expiration Thread Lock Contention

I recently helped introduce a Varnish cluster at work to offload a significant number of requests from a heavily-trafficked internal web service. This Varnish cluster serves approximately 10,000 requests/second (with peaks in the 20-30,000 requests/second range) 24x7x365. While working on this project I ran into a few interesting problems with Varnish. The most interesting one I saw was that Varnish would consume more and more RAM until eventually it would consume all the memory on the box and crash.