#13615: Nondeterminism in ‘pure’ function w/ parallel evaluation & memo combinators -------------------------------------+------------------------------------- Reporter: pacak | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.2.1-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): I have confirmed that eliminating the use of `parMap` in `solve` eliminates the issue as does replacing `rdeepseq` with `rseq`. I don't know whether the use of the `memo` combinator contributes as runtime blows up when it is removed Both uses of `A.unsafeUpdateM` in `unsafeInsertWith` (one in the `BitmapIndexed` branch and one in the `Full` branch) are problematic. Replacing either one with `A.update` decreases the failure rate, but the rate is still non-zero. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13615#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler