node health

J Davis mrsalty0 at
Wed Oct 17 12:22:39 UTC 2007

Many thanks. It sounds like using an outside health check to modify the
nodefile is probably the way to go.
I found the code that sets the NODEFILE_RELOAD_FREQ to 3 in so I
guess that means it checks for updates every three seconds as long as I
don't add/remove nodes through the management service.


On 10/16/07, dormando <dormando at> wrote:
> > I don't know of a way to do this through normal configuration or
> > plugins, but you could check out, the functions
> > event_write and event_read_waiting_options are the ones that currently
> > deal with the OPTIONS check.  You could modify it hit a specific URI
> > with a GET, instead... and then check for some magical "We're all good"
> > in the headers, I guess.  Keep in mind that the OPTIONS check is
> > currently when you first get a request (afaik), and it's assumed to be
> > very fast.  If your DB check takes a while it could block the first
> > unlucky user's request... if I'm reading it correctly.  Just sort of
> > stabbing here, I'm not a Perlbal pro.  I'm sure you're better off with
> > the next option.
> OPTIONS is only ran when perlbal first connects to an individual apache
> process, so it's not used for the client side service. For each
> keepalive request it'll just blind forward. It's better to have a health
> check service for the (often rarer) case of the code on an individual
> machine exploding.
> > Sure, your app (daemon or cron, whatever) could check your server for
> > connectivity then either ADD/REMOVE servers from a POOL via the telnet
> > management port, or change a nodelist file (which Perlbal will
> > eventually re-read).
> Yup :) It'll reload the nodelist pretty fast, even! As a caveat (this at
> least _used_ to be true), once you modify a pool with ADD/REMOVE, it
> won't check the nodelist anymore.
> -Dormando
-------------- next part --------------
An HTML attachment was scrubbed...

More information about the perlbal mailing list