How can I monitor recurrent rake tasks run by heroku scheduler?

Question

I just got the last month heroku bill, and the scheduled rake tasks were a relatively heavy burden. We are pretty early in our development process, so we just developed some rake tasks to get the job done recently, and didn't had much concern in theirs optimization.

Now we want to improve theirs performance and theirs heroku processing hours usage. We use New Relic to monitor the webapp performance, but apparently this type of rake tasks are ignored by default, and it's unclear how to override that.

Anyone had a similiar problem? How can I track the scheduled tasks in close to real time to monitor performance, optimize, and don't get suprise bills?

Answer 1

Whilst you can't really monitor rake tasks that well, there are a few little things you can do. One is the use of logging. Output start and end times of tasks to logs, and you can then see what's been happening duration wise. If you couple this with something like the Papertrail add-on then you can do additional interrogation later on.

As for running the jobs themselves, there's a couple of ways that you can run background processes which are dependant on how they need to run:

If you're needing to run jobs on a schedule, there's a few options available. Firstly there's the Heroku scheduler, which is pretty good, but doesn't guarantee executions will happen. Normally you would use this to kick off a rake task which will bring up a one-off dyno for the duration of the task - therefore you need to ensure in development that these tasks are as efficient as possible.

Alternatively, if you're looking at jobs that need a little more control or using a clock process. Essentially this is a dyno running 24/7 that does nothing but kick off other jobs at preset intervals and times. This would normally be done using the clockwork gem. The downside of this approach is that you need to pay for a clock process all the time.

A third approach, and one that might work is delayed job, with it's runat option, allowing you to queue a job to be run in the future (and jobs can re-queue themselves). There are a few issues with this in that a failure can kill the whole chain, and you need a full time worker running to process them all.

Therefore, in order to minimize your bills, ensure that your rake tasks are as performant and reliable, and then choose the scheduling option that suits you. If you're looking at schedules plus user created events, delayed_job might be the best option. If you're looking at a few tasks running periodically, then go scheduler. If you're looking at running lots of time critical jobs on a regular basis, go with clockwork.

Either way, you should be able to constrain a fair amount of processing into just one or two processes depending on your approach.