#9520: Running an action twice uses much more memory than running it once -------------------------------------+------------------------------------- Reporter: snoyberg | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Runtime | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by edsko): As Andres points out, my version 3 is not particularly enlightening; without any optimization, the loop in `feed` is not tail recursive (this relies on unfolding of `>>`); with optimization, we are bitten by the full laziness problem again. Bit of a red herring. (I had been trying to simulate the `hIsEOF` in the original example.) So I guess the only take away from my experimentation is: CAFs/full laziness and profiling modes interact in ways that make memory behaviour very unpredictable. Proceed with caution. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9520#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler