On Thu, Feb 16, 2012 at 2:04 PM, Michael Craig
When I read the docs for System.Mem.Weak, it all seems to make sense. But then this code doesn't run as I expect it to when I turn on -threaded: http://hpaste.org/63832 (Expected/actual output are listed in the paste.)
I've tried this on 7.4.1 and 7.0.4 with the same results. Can someone enlighten me?
First off, I'm pretty sure finalizers won't run until the data they were associated with has been GCd, and GHC doesn't do GCs unless there is allocation - threadDelay doesn't allocate much, I imagine. Also, from the docs: """ A weak pointer may also have a finalizer of type IO (); if it does, then the finalizer will be run at most once, at a time after the key has become unreachable by the program ("dead"). The storage manager attempts to run the finalizer(s) for an object soon after the object dies, but promptness is not guaranteed. It is not guaranteed that a finalizer will eventually run, and no attempt is made to run outstanding finalizers when the program exits. Therefore finalizers should not be relied on to clean up resources - other methods (eg. exception handlers) should be employed, possibly in addition to finalisers. """ Antoine