How to profile a Haskell program
- Just jotting down my notes whilst profiling one of my helper scripts. It would be great if the community could transform this into a tutorial
1 The case study
I have a script that converts from an XML format to some pickled data structures via Data.Binary. The XML part is generated by HaXml's DtdToHaskell. On a 54M XML file, the thing swaps like crazy and takes several hours. I would like to improve the situation.
2 Setting things up
2.1 Enable profiling on libraries
For example, my script uses HaXmL, which uses a library called polyparse:
cd polyparse runhaskell Setup.hs configure --enable-library-profiling runhaskell Setup.hs build sudo runhaskell Setup.hs install cd ..
cd HaXml runhaskell Setup.hs configure --enable-library-profiling runhaskell Setup.hs build sudo runhaskell Setup.hs install
2.2 Enable profiling on your stuff
Note that I assume you are using Cabal. If not, see How to write a Haskell program. It's super easy, and you'll be happy you did it.