Ensure that a given process is only running once. Helpful for ensure that scheduled tasks do not overlap if they run longer than the scheduled interval.
Prior attempts simply used a pid file, and checked if the process specified was still running (by calling
Process.kill(0, pid)), but
since the system reuses PID's you can get false positives. This project uses a locked pid file to ensure that the process is truly still
running. So basically, if the file is locked the process is still running.
This process is currently tested in nearly every ruby version supported by Travis-CI
- MRI versions 1.8.7, 1.9.2, 1.9.3, 2.0.0
- JRuby running in either 1.8 or 1.9 mode
- Rubinius running in either 1.8 or 1.9 mode
Add this line to your application's Gemfile:
And then execute:
Or install it yourself as:
$ gem install singleton_process
The basic usage is quite simple: just supply a process name (will show up in
ps ax output) and call
If you just want to exit if you can't lock call
SingletonProcess.new('long_running_process').lock_or_exit # will call Kernel.exit if it is already running.
By default the lock file will be removed when the process exits, but if you need to clear the lock earlier you can call #unlock.
process = SingletonProcess.new('long_running_process') process.lock # your process here process.unlock
If you want only a specific block of code to be locked call
#run! with the block.
SingletonProcess.new('long_running_process_name').run! do # some long running code here end
- Fork it
- Create your feature branch (
git checkout -b my-new-feature)
- Commit your changes (
git commit -am 'Add some feature')
- Push to the branch (
git push origin my-new-feature)
- Create new Pull Request