Unicorn 0.97.0 old master is never dying

Eric Wong normalperson at yhbt.net
Fri Mar 19 04:23:35 EDT 2010

ghazel at gmail.com wrote:
> On Thu, Mar 18, 2010 at 1:40 AM, Eric Wong <normalperson at yhbt.net> wrote:
> > ghazel at gmail.com wrote:
> >> I upgraded to Unicorn 0.97.0 from 0.96.1. Unicorn starts fine, but
> >> sending a USR2 to the 0.97.0 master launches a new master and all the
> >> workers, but never kills the old master. The new workers retry binding
> >> their admin TCP ports forever. Killing all the Unicorns and
> >> downgrading to returns peace to the forest.
> >>
> >> Here are the before_fork and after_fork from my config/unicorn.rb:
> >> http://codepad.org/5LyVtyq7
> >>
> >> Did something change with the Unicorn master in 0.97.0 that would
> >> require a change in my config, or is this a bug?
> >>
> >> -Greg
> >
> > Hi Greg,
> >
> > Odd, are you passing the pid file path via the command-line?
> >
> > I don't see the pid directive in the config file you posted there, so
> > there was nothing to check with File.exists?.  Are you using `unicorn'
> > or `unicorn_rails'?
> >
> > There were some startup changes in 0.97.0, but I couldn't reproduce what
> > you're seeing with 'pid'.  That said, I'm not sure if that method of
> > killing old masters in the after_fork is very common.
> >
> > --
> > Eric Wong
> >
> Eric,
> I am using "unicorn_rails -D -E $ENV -c config/unicorn.rb". Here is
> the entire config file: http://codepad.org/v6lUsuzD

Ugh.  I can't even get to that file right now.  I actually prefer
to have config files inline so:

a) I can comment easily on them
b) I don't have to be online when reading them
   (I sync my mail to a local machine and lose connectivity often)

On a side note, maybe an strace/truss can help figure out what's
going on.  James seems to be having a similar problem in the other

> What is the preferred way to do an nginx-style restart? My system does
> not really have the memory to start twice the number of workers.

If you're doing it during low traffic periods, I would SIGTTOU away
most (maybe all but one) of your workers and then SIGHUP the master

Eric Wong

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