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unicorn.rb - USR2 workaround
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# Sample verbose configuration file for Unicorn (not Rack) | |
# | |
# This configuration file documents many features of Unicorn | |
# that may not be needed for some applications. See | |
# http://unicorn.bogomips.org/examples/unicorn.conf.minimal.rb | |
# for a much simpler configuration file. | |
# | |
# See http://unicorn.bogomips.org/Unicorn/Configurator.html for complete | |
# documentation. | |
application = ENV['APP_NAME'] | |
# Use at least one worker per core if you're on a dedicated server, | |
# more will usually help for _short_ waits on databases/caches. | |
worker_processes (2) | |
# Help ensure your application will always spawn in the symlinked | |
# "current" directory that Capistrano sets up. | |
working_directory "/srv/#{application}" # available in 0.94.0+ | |
# listen on both a Unix domain socket and a TCP port, | |
# we use a shorter backlog for quicker failover when busy | |
listen "/srv/#{application}/tmp/sockets/unicorn.sock", :backlog => 2048 | |
#listen 8080, :tcp_nopush => true | |
# nuke workers after 30 seconds instead of 60 seconds (the default) | |
timeout 30 | |
# feel free to point this anywhere accessible on the filesystem | |
pid "/srv/#{application}/tmp/pids/unicorn.pid" | |
# By default, the Unicorn logger will write to stderr. | |
# Additionally, ome applications/frameworks log to stderr or stdout, | |
# so prevent them from going to /dev/null when daemonized here: | |
stderr_path "/srv/#{application}/log/unicorn.stderr.log" | |
stdout_path "/srv/#{application}/log/unicorn.stdout.log" | |
# combine REE with "preload_app true" for memory savings | |
# http://rubyenterpriseedition.com/faq.html#adapt_apps_for_cow | |
preload_app true | |
GC.respond_to?(:copy_on_write_friendly=) and | |
GC.copy_on_write_friendly = true | |
before_fork do |server, worker| | |
Signal.trap 'TERM' do | |
puts 'Unicorn master intercepting TERM and sending myself QUIT instead' | |
Process.kill 'QUIT', Process.pid | |
end | |
Signal.trap 'USR2' do | |
puts 'Since a black hole is lurking and eating USR2s we will hit http_server#reexec ourselves' | |
server.send(:reexec) | |
end | |
# the following is highly recomended for Rails + "preload_app true" | |
# as there's no need for the master process to hold a connection | |
defined?(ActiveRecord::Base) and | |
ActiveRecord::Base.connection.disconnect! | |
# When sent a USR2, Unicorn will suffix its pidfile with .oldbin and | |
# immediately start loading up a new version of itself (loaded with a new | |
# version of our app). When this new Unicorn is completely loaded | |
# it will begin spawning workers. The first worker spawned will check to | |
# see if an .oldbin pidfile exists. If so, this means we've just booted up | |
# a new Unicorn and need to tell the old one that it can now die. To do so | |
# we send it a QUIT. | |
# | |
# Using this method we get 0 downtime deploys. | |
old_pid = "#{server.config[:pid]}.oldbin" | |
if File.exists?(old_pid) && server.pid != old_pid | |
begin | |
Process.kill("QUIT", File.read(old_pid).to_i) | |
rescue Errno::ENOENT, Errno::ESRCH | |
# someone else did our job for us | |
end | |
end | |
# The following is only recommended for memory/DB-constrained | |
# installations. It is not needed if your system can house | |
# twice as many worker_processes as you have configured. | |
# | |
# # This allows a new master process to incrementally | |
# # phase out the old master process with SIGTTOU to avoid a | |
# # thundering herd (especially in the "preload_app false" case) | |
# # when doing a transparent upgrade. The last worker spawned | |
# # will then kill off the old master process with a SIGQUIT. | |
# old_pid = "#{server.config[:pid]}.oldbin" | |
# if old_pid != server.pid | |
# begin | |
# sig = (worker.nr + 1) >= server.worker_processes ? :QUIT : :TTOU | |
# Process.kill(sig, File.read(old_pid).to_i) | |
# rescue Errno::ENOENT, Errno::ESRCH | |
# end | |
# end | |
# | |
# # *optionally* throttle the master from forking too quickly by sleeping | |
# sleep 1 | |
end | |
after_fork do |server, worker| | |
Signal.trap 'TERM' do | |
puts 'Unicorn worker intercepting TERM and doing nothing. Wait for master to sent QUIT' | |
end | |
# per-process listener ports for debugging/admin/migrations | |
# addr = "127.0.0.1:#{9293 + worker.nr}" | |
# server.listen(addr, :tries => -1, :delay => 5, :tcp_nopush => true) | |
# the following is *required* for Rails + "preload_app true", | |
defined?(ActiveRecord::Base) and | |
ActiveRecord::Base.establish_connection | |
# if preload_app is true, then you may also want to check and | |
# restart any other shared sockets/descriptors such as Memcached, | |
# and Redis. TokyoCabinet file handles are safe to reuse | |
# between any number of forked children (assuming your kernel | |
# correctly implements pread()/pwrite() system calls) | |
end |
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