socket performance degrades by c. 20-30% when compiling with -threaded
This is not a cloud haskell issue at all, but rather it's a GHC one. Nonetheless we should file a GHC ticket at some point to get it looked at.
Thanks Rob, good catch. Let's see what Edsko has to say.
This may be have been addressed in the Mio parallel IO manager: http://haskell.cs.yale.edu/wp-content/uploads/2013/08/hask035-voellmy.pdf It will be the default IO manager from GHC 7.8. Indeed, it directly points to Edsko's blog post ( http://www.edsko.net/2013/02/06/performance-problems-with-threaded/ ) in Section 6.4. I don't know whether Edsko's benchmarks have been re-run against GHC HEAD with Mio merged? This would answer whether the 20-30% is still present using Mio. Perhaps knows.