#11508: QuickCheck application hangs with concurrent read/write of Chan -------------------------------------+------------------------------------- Reporter: orion | Owner: Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: x86_64 | (amd64) Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by erikd): Went away and did something else and then it occured to me that QuickCheck must be silently swallowing the "blocked MVar" exception. Looking at the code for `readChan` and `writeChan` from `Control.Concurrent.Chan` we can see that they are implemented with `MVars`. Interestingly, the docs for `Control.Concurrent.MVar` do warn about "race conditions, deadlocks or uncaught exceptions", but the docs for `Control.Concurrent.Chan` do not reflect this, and neither do they mention the `STM` implementation of channels in `Control.Concurrent.STM.TChan` which are far more robust than the `MVar` version. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11508#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler