diff options
| -rw-r--r-- | lib/unicorn.rb | 35 |
1 files changed, 27 insertions, 8 deletions
diff --git a/lib/unicorn.rb b/lib/unicorn.rb index 86458ac..1d22442 100644 --- a/lib/unicorn.rb +++ b/lib/unicorn.rb @@ -84,6 +84,17 @@ module Unicorn self.init_listeners = options[:listeners] ? options[:listeners].dup : [] self.config = Configurator.new(options.merge(:use_defaults => true)) self.listener_opts = {} + + # we try inheriting listeners first, so we bind them later. + # we don't write the pid file until we've bound listeners in case + # unicorn was started twice by mistake. Even though our #pid= method + # checks for stale/existing pid files, race conditions are still + # possible (and difficult/non-portable to avoid) and can be likely + # to clobber the pid if the second start was in quick succession + # after the first, so we rely on the listener binding to fail in + # that case. Some tests (in and outside of this source tree) and + # monitoring tools may also rely on pid files existing before we + # attempt to connect to the listener(s) config.commit!(self, :skip => [:listeners, :pid]) self.orig_app = app end @@ -170,6 +181,11 @@ module Unicorn end end unlink_pid_safe(pid) if pid + + # not using O_EXCL here since we may be (intentionally) clobbering an + # existing file. Avoiding /all/ possible race conditions with the pid + # file is hard so we don't unlink it before writing nor do we rename() + # since that's clobbering, too... File.open(path, 'wb') { |fp| fp.syswrite("#$$\n") } if path self.set_pid(path) end @@ -589,7 +605,9 @@ module Unicorn end # unlinks a PID file at given +path+ if it contains the current PID - # useful as an at_exit handler. + # still potentially racy without locking the directory (which is + # non-portable and may interact badly with other programs), but the + # window for hitting the race condition is small def unlink_pid_safe(path) (File.read(path).to_i == $$ and File.unlink(path)) rescue nil end @@ -597,14 +615,15 @@ module Unicorn # returns a PID if a given path contains a non-stale PID file, # nil otherwise. def valid_pid?(path) - if File.exist?(path) && (wpid = File.read(path).to_i) > 1 - begin - Process.kill(0, wpid) - return wpid - rescue Errno::ESRCH - end + wpid = File.read(path).to_i + wpid <= 0 and return nil + begin + Process.kill(0, wpid) + return wpid + rescue Errno::ESRCH + # don't unlink stale pid files, racy without non-portable locking... end - nil + rescue Errno::ENOENT end def load_config! |