#881: Improve space profiling for references
--------------------------------+-------------------------------------------
Reporter: simonpj | Owner:
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Profiling | Version: 6.4.2
Severity: normal | Keywords:
Os: Unknown | Difficulty: Unknown
Architecture: Unknown |
--------------------------------+-------------------------------------------
GHC's great space profiling tools don't appear to be much help when your
leaked memory is stored in references (IORefs, StablePtrs, etc). I had
a real-life case where the allocation profile showed me where the leaked
data came from, and I could guess that it was being held by some
reference, but I couldn't tell which one. Retainer set profiling showed
a big suspicious entry for "SYSTEM", but I couldn't find any way to
pinpoint the problem. (It ended up being a missing freeStablePtr in
hsgnutls, found by code inspection.)
Here's a contrived example that just allocates a bunch of IORefs:
{{{
import Control.Monad
import Data.IORef
main = repeatM (newIORef [1,2,3])
repeatM io = liftM2 (:) io (repeatM io)
}}}
Retainer set profiling shows everything in "SYSTEM". None of the other
profiling methods say anything interesting either. What I'd like to
get, I think, is (1) your memory is being held in IORefs (2) allocated
by this cost center and (3) being retained by this cost center. I guess
I'm looking for something like a memory profiler for a traditional
language.
Andrew Pimlott
Simon Marlow comments: "The relevant predicate "is retainer" is pretty
much built into the retainer profiler, and it returns true only for thunks
if I recall correctly. Being able to tweak this, or maybe just install a
better default would be an improvement.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/881>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
