IORefs and garbage collection
ravi at bluespec.com
Tue Apr 18 16:05:28 EDT 2006
I recently discovered that I'm running into the IORef / garbage
collection issue described in the ghc user guide (at the bottom of the
Increasing the heap and allocation area size (with -H, -M and -A) helped
improved my runtimes considerably (by preventing all of my execution
time from being sucked up by the garbage collector), but I have some
1. What "goes wrong" with mutable data and generational garbage
collection to make this sort of workaround necessary? The issue
surprised me because I thought there was plenty of satisfied experience
with generational gc for languages with many more destructive updates
(e.g. Java) than Haskell. Is there some optimization that the ghc
runtime is not implementing?
2. If there is a known fix for this issue, what would it involve (and,
if there are any guesses, how much work might it be)?
3. What is the best workaround for this issue if you *don't* know the
maximum amount of memory available for your program? Would be it be best
to fall back copying collection if you want your program to consume and
release memory "as needed" or is there a cleverer trick?
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