Varnish Cache 6.0.0
I work in the CDN industry and am also heavily involved in the FreeBSD community.  I find Varnish to be kind of a tragic curiosity in that is has nice fit and finish but is pretty unsuitable for high scale workloads due to the influence of its creator phk@.  Ironically on the OS he should know like the back of his hand, sched_ule(4) has fairly expensive depth searches to ensure process fairness.  Doing a thread per connection is about the worst conceivable design for web acceleration.  It is probably ok for low connection count high bandwidth (like chunked video streaming), but you&#x27;re still going to be dropping performance on the floor vs other I&#x2F;O models as you get into the 1000s of connections, and as Netflix has publicly shown that is modern reality on FreeBSD with 100gbit networking.<p>My understanding is that fastly has rewritten the I&#x2F;O model upon more industry standard event polling worker threads.  They also reworked a lot of the memory model using <a href="https:&#x2F;&#x2F;github.com&#x2F;fastly&#x2F;uslab" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;fastly&#x2F;uslab</a>.  None of that I&#x2F;O work is upstream and it&#x27;s unlikely it ever will be because of the phk@ influence and perhaps fastly sees it as IP.  So be prepared to do some deep systems work if you need high scalability out of Varnish.<p>Apache Traffic Server is the most ready &quot;out of the box&quot; caching software for rolling a CDN that I&#x27;ve seen.  If you&#x27;re going to do custom development, nginx is a good I&#x2F;O and HTTP model but be prepared to roll a complete cache storage model from scratch.