Delayed Job

In a project I'm working on, when a report was published it would generate a PDF (using the very convenient <a href="http://prawn.majesticseacreature.com/">Prawn</a>) and then send that PDF to half a dozen subscribers. This took a while (around 5 seconds) and made the response to the user a little slow. Actually, it was even worse than that. If I sent the PDF to 5 subscribers then I generated the PDF 5 times (and again each time it was viewed online). My first step was to write the PDF out to the local filesystem so that I only ever had to generate it once. For further peace of mind, I also copied the PDF to S3. I then chose <a href="http://github.com/collectiveidea/delayed_job">Delayed Job</a> (the CollectiveIdea fork) to start processing everything in the background. Now, when a report is published then the a job is created and the user gets a snappy response. Following advice from Ryan Bates (<a href="http://railscasts.com/episodes/171-delayed-job">Railscast 171</a>) I started to think about what to do if the PDF publiction job failed half way through. The risk here is that if you email 5 people and the fifth one fails then the whole job fails and it is rerun a bit later. This would mean repeated emails to the first 4. My first plan was a new table that recorded which PDF had been sent to whom - then it occurred to me that I could just 'spawn' new jobs for each separate email. That way, only the failed email gets reattempted. So now I have a primary job that gets run which generates the PDF and then creates a handful of other jobs that actually send the emails out. Nice. P.S. Exactly one year since my last post and its title is "Delayed Job". How appropriate.

2009-11-30T02:49:07+00:00

Using the delayed_job Rails plugin for background tasks, sending emails. I love it when code gets simpler. 18 /home/logical/rails/shared/images/post/image/18/rails.png 2009-11-30 Delayed Job

2009-11-30T02:50:56+00:00