By: Matthew Turland

Matthew Turland — Tue, 25 Nov 2008 03:03:09 +0000

As far as I can tell, Ubuntu does not have a DNS cache running by default. nscd is available as a package for it and I tried installing it, but found this comment in the configuration file:

# hosts caching is broken with gethostby* calls, hence is now disabled
# per default. See /usr/share/doc/nscd/NEWS.Debian.

So I uninstalled that and followed this tutorial to install, configure, and test dnsmasq instead:

http://ubuntu.wordpress.com/2006/08/02/local-dns-cache-for-faster-browsing/

I also amended a few oversights in my original example. The curl options array should include CURLOPT_FOLLOWLOCATION and the pecl_http options array should include ‘redirect.’ Using a GET request that results in a redirect as the test subject, I got the following results.

Before installing dnsmasq:
pecl_http – 12.75%
streams – 25.27%
curl – 12.92%
pear – 32.82%
zend – 24.50%

After installing dnsmasq:
pecl_http – 19.58%
streams – 21.40%
curl – 17.30%
pear – 28.20%
zend – 21.10%

So, a local OS-level DNS cache does bring the performance of these clients significantly closer to equal footing. Lars and Pierre, thanks for helping to clear this up!

By: Lars Strojny

Lars Strojny — Mon, 24 Nov 2008 14:04:51 +0000

Was nscd (name service cache daemon) running? Don’t know what’s the default on Ubuntu.

By: Pierre

Pierre — Sun, 23 Nov 2008 19:13:26 +0000

CURL uses its own DNS cache system, independently of OS (if it implements any). The PECL HTTP uses CURL and its DNS cache (via the option dns_cache_timeout).

I do not think php has a DNS cache (but only did a quick grep, I’d to check again more deeply.

Comments on: Benchmarking PHP HTTP Clients

By: Matthew Turland

By: Lars Strojny

By: Pierre