Debugging scary crashes of Rubinius

Dirkjan Bussink 04 January 2012

Bugs, we all are in the infinite fight of getting rid of them. Sometimes they are trivial, other times a bit harder. In this video I'm going to show how I have been debugging an issue that caused memory corruption of your dear Ruby objects in Rubinius.

Background

It's a pretty long video clocking at 55 minutes but I'm trying to be detailed in the discovery process. I'm explaining the steps I'm taking along the way and explaining why I'm taking those.

The real debugging process if of course littered with taking wrong turns so please don't think I'm brilliant and able to zoom into the issue immediately all the time. The video is not recorded as I was going through it the first time, so I exactly knew where I was going and which steps to take.

If you want to look up some more information on GDB that I'm using in the video, here are some links that explain some of the most used commands in the video:

GDB - Examining data GDB - Setting watchpoints

During the video there's a part from 8:18 until 11:28 where it's just watching a rebuild of Rubinius scrolling by. I'd suggest skipping it since it's not very useful. I tried to remove it but after having to reencode the video it only grew larger. If anyone has more skills to fix that, please let us know!

Download

You can find the video on Vimeo:

Watch on Vimeo

It's probably best to download the video and play it locally on your machine. It's 453 MB so it might take a while.

Please let us know if you find this useful, we might do more of them in the future if there's interest!

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