On Thu, 2009-05-07 at 15:12 +0100, Neil Mitchell wrote:
This is a test framework that spawns system commands. My guess is the Haskell accounts for a few milliseconds of execution per hour. Running two system commands in parallel gives a massive boost.
That still doesn't explain why you need +RTS -N2. You can spawn multiple processes by making multiple calls to runProcess or whatever. If you want to wait for multiple processes simultaneously, compile with -threaded and use forkIO.
I do need to wait for them - so I don't end up firing too many at once. I was hoping to avoid the compile, which the ghc -e will give me.
Right, it works because ghc itself is compiled with the threaded rts. So you don't need the +RTS -N when you call ghc -e. Note that for the next ghc release the process library will use a different implementation of waitForProcess (at least on Unix) so will not need multiple OS threads to wait for multiple processes simultaneously. Duncan