Yesterday we encountered an odd situation. A rake task running with heroku that did not finish. Through no fault of our own.
We killed the local processes kicked off by the
heroku command line tool and restarted the rake task but got an error message about only allowing one free dyno. Apparently, the dyno supporting our rake task was still in use.
First we had to examine whether that was true with:
heroku ps -a myapp
Next step was to kill the dyno with the identifier provided by the above command.
heroku ps:kill dyno.1 -a myapp
We ran the rake task again, everything was fine, it worked great.