1. Squid, a veteran reverse proxy software, offers advanced features like traditional proxying, authentication, and traffic management, but its configuration is notoriously complex. It is arguably the most widely deployed reverse caching proxy server on the internet today, operating across many established CDNs.
2. Varnish is a newer piece of software with a simpler design that better suits today’s internet applications. Many companies have adopted Varnish, for example, Weibo’s open API at http://open.t.sina.com.cn . Varnish is based on memory caching, so data is lost upon restart.
3. Nginx’s reverse proxy caching is implemented through a module called proxy_cache. This module is still being refined, but many companies have already started using it.
People in the group are always asking what to use for cache; options include Varnish, Squid, Apache, and Nginx. Which architecture should we actually use for caching?
1. In terms of functionality, Varnish and Squid are professional caching services, whereas Apache and Nginx achieve this through third-party modules.
2. If you need a caching service, you definitely want to choose a professional one, prioritizing Squid and Varnish.
Varnish has a technical edge over Squid. It employs “Visual Page Cache” technology, giving it an advantage in memory utilization over Squid. It avoids Squid’s frequent swapping of files between memory and disk, resulting in higher performance. Varnish cannot cache to a local hard disk.
Also, through its powerful management port, Varnish allows you to use regular expressions to quickly and batch-purge selective cache entries.
Squid’s advantage lies in its comprehensive and extensive cache documentation and numerous production environments (likely due to its earlier release).
3. Regarding Nginx, it performs caching using a third-party module called ncache, and its performance is close to Varnish’s. However, in an architecture, Nginx is generally used as a reverse proxy (for static files, Nginx is widely used now, with concurrency support reaching 20,000+). In a static file architecture, if the front end directly faces a CDN or has a Layer-4 load balancer in front, then Nginx’s cache alone is fully sufficient.
4. In my opinion, if you are boosting performance on an Apache server, doing some local caching is perfectly fine. But if you are positioning Apache as a cache service within your system architecture, that is completely incongruous.
Test results show that Varnish > Nginx > Apache > Squid. I think this outcome differs somewhat from everyone’s expectations. How