On Sunday 09 October 2011, 17:51:06, Jean-Marie Gaillourdet wrote:
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''' #-}
That'll make it very improbable to get bad results, but not impossible. Thread1: typeOf' (); typeOf'' (), lookup, not there Thread2: typeOf' (); typeOf'' (), lookup, not there Thread1: create and insert; typeOf''' (), entry present, use ~> Key 0 Thread2: create and insert, overwites entry with Key 0, new entry has Key 1; typeOf''' (), entry present, use ~> Key 1 It will probably take a long time until it bites, but when it does, it will hurt. A proper fix would need a lock to ensure only one thread at a time can access the cache.