#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 (amd64) Type of failure: Runtime | Difficulty: Unknown performance bug | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by snoyberg):
So if `main6` generates a big data structure, it will be retained across both calls.
Well, that's sort of the idea: conduit is essentially a free monad, and it's evaluated by interpreting steps like "wait for next input" or "provide next value." What *should* be happening is that it creates a value indicating the next step, and that value is immediately consumed and garbage collected. Instead, for some reason it's maintaining this structure between multiple calls, even though the two data structures will not match (not that the `Handle` used by each loop will be different). Hopefully the base-only version of the code will demonstrate the issue more clearly. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9520#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler