68 lines
2.1 KiB
Markdown
68 lines
2.1 KiB
Markdown
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---
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title: Profiling in Haskell
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author: nek0
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tags: programming, english
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description: How to perform profiling on your Haskell projects
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---
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On of my projects is a game engine called "Affection". Its design is loosely
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based on the game engine "Löve" for Lua.
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Because I have been doing it a lot recently in this project, I would like to
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make public the method of profiling I use.
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## Prerequisites
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first of all, you will need the profiling libraries for Haskell, which in Debian
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you can find in the `ghc-prof` package.
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Next you need to enable profiling in your build environment. You can do this
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either globally or per-package. If you want to enable it globally, you just need
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to add
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```Cabal
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profiling: True
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```
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to your `~/.cabal/config` file.
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If you want to enable it per-package, you need to add the same line to a
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`cabal.config` in your projects root directory (The same directory your
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`*.cabal` file is located.
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When enabling profiling, it might happen, that you need to reinstall a whole
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lot of packages. Sandboxing your project might be a good idea.
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## Compiling
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Recompiling your projects with profiling options should be easy. Just invoke
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`cabal build`.
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## Profiling
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After your build succeeded, you can start profiling your executables by
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```Bash
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path/to/executable +RTS -hc
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```
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Your executable will run as expected, you can try it out and everything. When
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your application terminates, it produces an file ending with `.hp`, containing
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your profiling information. Its content is rather cryptic, but that doesn't
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matter. There are tools even for that. You can try running
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```Bash
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hp2ps -c executable.hp
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```
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where `executable` is the name of your executable. This produces a `.ps` file,
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a simple postscript file, that you can open with your PDF-viewer. You will see
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a graph showing memory allocation per function, which might lead you to memory
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leaks or similar problems.
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If you want to profile your executable by datatype memory allocation, just run
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the profiling command (the one with the `+RTS`) and write `-hy` instead of `-hc`
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.
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I hope this helps you out hunting your bugs, it sure helped me a lot.
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