#4001: Implement an atomic readMVar -------------------------------------------+-------------------------------- Reporter: simonmar | Owner: ezyang Type: task | Status: new Priority: low | Milestone: 7.6.2 Component: Runtime System | Version: 6.12.2 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Moderate (less than a day) | Testcase: Blockedby: | Blocking: Related: | -------------------------------------------+-------------------------------- Changes (by ezyang): * owner: => ezyang Comment: On a whim, I decided to implement atomicReadMVar. Details: * Adds an extra word to the size of StgMVar; someone needs to find out how expensive this is. * Adds an extra memory dereference to putMVar/tryPutMVar, since they now need to check if there are any threads which are waiting on reads. Otherwise, it's implemented exactly as Simon described it. I still don't know if this is a good idea, but it does seem that a "wake all" semantics might be pretty useful for MVars. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/4001#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler