completely stumped by problem encountered replacing running unicorn

Justin Giancola justin.giancola at
Thu Oct 14 00:58:49 EDT 2010


First off, many thanks to all those who have contributed to this great
project. I have been running Unicorn in production for quite some time
now. It hass been very reliable and I have really enjoyed being able
to deploy frequently without downtime or even dropped connections.

I have used the USR2+QUIT upgrade procedure as described in SIGNALS
since I started using Unicorn and it works great. However, while
upgrading Bundler on my server the other day, an upgrade failed for
the first time. The upgrade failed due to a LoadError -- <application
root>/gems/environment.rb is no longer used in Bundler 1.0 so it was
missing from the new application tree.

I am using a Capistrano setup so my app is located at
/path/to/app/current where current is a symlink to a timestamped
release directory. I am calling #working_directory in my unicorn
config to set it to the symlinked current path. I am also calling
unicorn via a binstub generated by Bundler located at

I had expected that reexec would pick up the new unicorn and app code
because the path to the unicorn executable script, the path to my app,
and config files were all identical to those used in the previous
deploy. However, this is not what is happening. Rather, it looks like
the previous version of the code is trying to reload iteself in the
new app tree where files are missing.

I am having a very difficult time understanding exactly what files are
being reloaded during the reexec. Even my attempts at troubleshooting
where the load error is originating have left me completely baffled.
In the old app gems/environment.rb is required in a few places but
none of those files seem to be reloaded during the reexec. Further, I
cannot get this executable swap to work no matter what I try. I have
even tried getting rid of the symlinks entirely and changing the
contents of the /path/to/app/current in place during the upgrade.

I feel like I may be missing something obvious or else I have
completely misunderstood how the reload process works. Any insight as
to what I should be doing differently would be greatly appreciated.


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