Re: [Haskell-cafe] code review? store server, 220loc.

On Sat, Aug 2, 2008 at 10:13 PM, Tim Newsham wrote:

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http://www.thenewsh.com/%7Enewsham/store/Server5.hs

You should try profiling this. I can see a few possible problems (such as reading String from a socket, instead of a ByteString), but it's difficult to predict what might be causing your code to be so slow. Haskell code ought to be much more competitive with C for an application like this.

Profiling didn't turn up anything obvious: http://www.thenewsh.com/~newsham/store/Server9.prof one thing I dont quite understand is that it seems to be crediting more time to "put8" and "get8" than is warranted, perhaps all of the "get" and "put" functions... One suprising result from testing: http://www.thenewsh.com/~newsham/store/TestBin.hs shows that the Data.Binary marshalling is actually very fast, but when I want to add a length field at the start of the buffer it has a huge impact on performance. I've tried several variations without much luck... (also the third test case is very odd in that skipping a conversion to strict bytestring actually makes it slower(!)). soo... I think thats probably one of the things limiting my performance. Another one is probably my need to do two reads (one for length one for the data) for each received record... I think with some trickiness I could get around that (since recv will return only as many bytes as are immediately available) but I don't know that its worth the effort right now.... Anyway, any thoughts, especially on how to make the bytestring operations faster, would be appreciated. Tim Newsham