DNS bottleneck

[reinh]

DNS bottleneck

[reinh]

That is unfortunate. I may not have much control over DNS resolution but I will look into it. You could of course use an IP instead of a hostname.

[mdp]

You could also do this in the library with something along the lines of:

def initialize(host, port)
  unless host.match(/^[^a-zA-Z].+$/)
    host = Resolv.getaddress(host)
  end

[ktheory]

This patch turns statsd into a badly behaving DNS client.

If the DNS of the hostname changes to a different IP address, one expects clients to pick up the change within the TTL. This patch seems to cache DNS for the lifetime of the process.

OTOH, I'm not observing that "DNS service is queried once per sent packet". In ruby 1.8.7 on OS X Lion, DNS works as expected: the first sent stat is slow, and subsequent stats are much faster for the duration of the TTL:

irb -rstatsd -rbenchmark
irb(main):001:0> Benchmark.realtime { Statsd.new("google.com").increment("foo") }
=> 0.0229549407958984 # Slow for DNS
irb(main):002:0> Benchmark.realtime { Statsd.new("google.com").increment("foo") }
=> 0.000710964202880859 # Too fast for a DNS request

Edit June 22 2014 0.00071 seconds (0.7ms) is not too fast for a DNS request. 🐳

[jeremy]

@ktheory indeed - pragmatic attempt to speed up the common case where DNS never changes, but this shouldn't be the client's job. I'll revert.