About Unicorn Rack handler

Eric Wong normalperson at yhbt.net
Thu Nov 5 02:29:00 EST 2009


"Lin Jen-Shin (aka godfat 真常)" <godfat at godfat.org> wrote:
> 2009/11/5 Lin Jen-Shin (aka godfat 真常) <godfat at godfat.org>:
> > On Thu, Nov 5, 2009 at 1:07 AM, Eric Wong <normalperson at yhbt.net> wrote:
> >> On the other hand, does Innate make it possible to do transparent
> >> upgrades (since rackup does not)?  I'll look into it a bit more later...
> >
> > I am not sure what do you mean transparent here,
> 
> Oops, accidentally sent incomplete mail, sorry.
> 
> I am not sure what do you mean transparent here,
> but I would guess Innate work better than rackup. :p

Transparent, zero-downtime upgrades (USR2 + QUIT) that Unicorn
can do like nginx[1].

The issue here with rackup is that it changes ARGV with the option
parser before Unicorn can get to it.  So when Unicorn receives the USR2
signal and respawns itself, it won't be able to spawn a child with the
same command-line options as its parent.  Using the "unicorn" script
will allow it to always save its ARGV before OptionParser has a chance
to mangle it.

[1] - http://unicorn.bogomips.org/SIGNALS.html
-- 
Eric Wong


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