Hi, On 09.10.2011, at 17:37, Jean-Marie Gaillourdet wrote:
Hi,
On 09.10.2011, at 17:27, Daniel Fischer wrote:
That's what I expect. I think what happens is:
-- from Data.Typeable
cache = unsafePerformIO $ ...
mkTyConKey :: String -> Key mkTyConKey str = unsafePerformIO $ do let Cache {next_key = kloc, tc_tbl = tbl} = cache mb_k <- HT.lookup tbl str case mb_k of Just k -> return k Nothing -> do { k <- newKey kloc ; HT.insert tbl str k ; return k }
occasionally, the second thread gets to perform the lookup before the first has updated the cache, so both threads create a new entry and update the cache.
If you loop in the Haskell programme, after the first round each thread definitely finds an entry for "()", so the cache isn't updated anymore.
That sounds plausible. Do you see any workaround? Perhaps repeatedly evaluating typeOf? typeOf' seems to be a working workaround:
typeOf' val | t1 == t2 = t1 | otherwise = typeOf' val where t1 = typeOf'' val t2 = typeOf''' val {-# NOINLINE typeOf' #-} typeOf'' x = typeOf x {-# NOINLINE typeOf'' #-} typeOf''' x = typeOf x {-# NOINLINE typeOf''' #-} Jean