#11500: C finalizer of a finalized ForeignPtr may be called again when RTS shuts down -------------------------------------+------------------------------------- Reporter: skydust | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 7.8.3 System | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The C finalizer of a ForeignPtr that was explicitly finalized (finalizeForeignPtr) is sometimes called again when the RTS shuts down. Expected behaviour: - The test script (./test.sh) below never stops Observed behaviour: - After a while, the test script stops with an error message indicating double free or memory corruption {{{#!sh $ ./test.sh }}} {{{ [1 of 1] Compiling Main ( finalizer_hs.hs, finalizer_hs.o ) Linking finalizer_hs ... *** Error in `./finalizer_hs': double free or corruption (!prev): 0x00000000010b85e0 *** ./test.sh: line 3: 20482 Aborted (core dumped) ./finalizer_hs +RTS -N 178 }}} File finalizer_hs.hs {{{#!hs {-# LANGUAGE ForeignFunctionInterface #-} import Foreign (Ptr, FunPtr, malloc) import Foreign.ForeignPtr (newForeignPtr, finalizeForeignPtr) import Control.Monad (forM, forM_) foreign import ccall "stdlib.h &free" p_free :: FunPtr (Ptr a -> IO ()) main :: IO () main = do fps <- forM [1 .. 10000] $ \_ -> do p <- malloc newForeignPtr p_free (p :: Ptr Int) forM_ fps finalizeForeignPtr }}} File test.sh: {{{#!sh ghc finalizer_hs.hs -threaded CNT=0 while ./finalizer_hs +RTS -N; do CNT=$((CNT+1)); done echo $CNT }}} Note: running several instances of ./test.sh concurrently triggers the problem faster Issue detected on following tested setups: - Linux 32bit GHC 7.10.2 - Linux 64bit GHC 7.8.3 - Linux 64bit GHC 7.8.4 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11500 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler