Use primes for hashtable size

[Maxim Dounin]

Hello!

On Fri, Jun 02, 2017 at 10:56:31AM +1000, Mathew Heard wrote:

> If this actually yields a decrease in start time while not introducing
> other effects we would use it. Our start time of a couple minutes is
> annoying at times.

Do you have any details of what contributes to the start time in 
your case?

In general, nginx trades start time to faster operation once 
started, and trying to build minimal hash is an example of this 
practice.  If it results in unacceptable start times we certainly 
should optimize it, though I don't think I've seen such cases in 
my practice.

Most time-consuming things during start I've seen so far are:

- multiple DNS names in the configuration and slow system 
  resolver;

- multiple SSL certificates;

- very large geo{} maps.

-- 
Maxim Dounin
http://nginx.org/