I've used ghc-events-analyze to debug production multi threaded software, and even have a wee patch or so in it. (Mostly for things like "why is my map reduce i

I've used ghc-events-analyze to debug production multi threaded software, and even have a wee patch or so in it. (Mostly for things like "why is my map reduce ish compilation not substantially faster on a 40 core computation vs a 20 core one"). It's a really great tool for seeing all the various events in a programs execution! That said, when processing event logs that are >=50mb (which can happen pretty easily), it's currently a bit memory hungry. Though that's something that should be easy to fix once I (or you dear reader) decide to have a go at fixing it. Also Edsko, the author, is a super nice guy and a very responsive maintainer.