Detecting unicorn / defining after_fork after master startup
normalperson at yhbt.net
Sun Jul 22 21:20:26 UTC 2012
Matt Sanders <matt at modal.org> wrote:
> On Thu, Jul 19, 2012 at 6:13 PM, Eric Wong <normalperson at yhbt.net> wrote:
> > Matt Sanders <matt at modal.org> wrote:
> >> 2. Is there an established way for adding an after_fork hook after
> >> Unicorn has already started up?
> > Nothing that I know of.
> >> I'm aware of the ability to do this via the config file but I don't
> >> want my users to have to add something to their unicorn config file.
> >> Is there an equivalent to passenger's
> >> PhusionPassenger.on_event(:starting_worker_process) method?
> > Lately, I've been favoring the following pattern instead:
> Thanks! I definitely agree in general with that pattern. In this case
> I'd ideally like some activity on the forked child before the next
> request cycle - that is, if the forked child doesn't serve any
> requests for a little bit, I'd still like my behavior to be
Yes, that sucks. I'll often just throw some requests at the child
just to start something up if I need it, or initiate a separate daemon.
> Do you know of a way to get this behavior without a direct after fork hook?
No, unfortunately not. I have considered petitioning for something
along the lines of pthread_atfork() in Ruby, but pthread_atfork() itself
also has unfortunate drawbacks (it makes fork() async-signal un-safe,
and thus _Fork() will be introduced in the next version of POSIX).
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