On Sat, Jun 19, 2010 at 8:46 AM, Claus Reinke
I put the simple version at http://hpaste.org/fastcgi/hpaste.fcgi/view?id=26329#a26329
This one displays much better performance with DList + Writer.Strict than List + StrictWriter so I guess it's not too surprising. However, *something* is still generating a lot of lag
Some lag is to be expected: logging is about creating and recording data for later use. You'd need to annotate
Indeed, though I don't think this is the case, because I get lots of lag even when no logs are written. I solved the stack overflow problem with state by replacing 'modify' with a stricter '!x <- get; put $! (x+1)'. However, the results from profiling logging continue to be mysterious. The fastest is using a strict StateT, prepending with 'modify (msg:)' and reversing the list on run. Oddly, making *this* modify strict results in a near 2x slowdown, perhaps due to a 27.7% productivity instead of a 31.8% productivity (though both are terrible, and I still don't know why all the garbage is being produced). Using Simon's AppendList (my implementation is based on OrdList from ghc), it's slightly slower than the strict modify version. Apparently reversing a 4194304 element list is still faster than using a custom datatype. My conclusion is that my contrived tests are not useful because the whole point is to get a controlled situation by simplifying it, but even the simple version displays mysterious behaviour. I should go back to poking at the production version. Even if I don't understand the changes I'm making, at least when I get a speedup I'm more sure it translates to a real speed up in the application.