使用ruby 2.0.0和Rails 3.2.14的Unicorn热重启

Question

I am running e-commerce ruby on rails application using Unicorn app server. The ruby version is 2.0.0 and the rails version is 3.2.14. I am running Nginx as web server. When ever I push the code to the server, I need to restart the unicorn app server, which is causing a blup/bleep in the website, I googled around for the solution but nothing seem to be working. I was using passenger before which was fine.

Is there any way to avoid blup's during restarting hence maintain zero downtime.

Answer 1

If you send USR2 to the unicorn master, it will cause the unicorn workers to restart, and should cause a zero downtime restart. Send the USR2 signal with:

kill -s USR2 process-id-of-master-process

Replace the process-id-of-master-process with the numeric process id of the unicorn master (find it with ps agx | grep unicorn, or look in the pids folder for unicorn.pid

Note that if unicorn is running under Bundler, you will still need to do a cold restart whenever you change the Gemfile, in order for the new Gemfile to be picked up.