Re: [Haskell-cafe] Re: Asynchronous exception wormholes kill modularity

On Thu, Apr 8, 2010 at 11:45 PM, Bas van Dijk wrote:

On Thu, Apr 8, 2010 at 9:15 PM, Isaac Dupree wrote:

...

I still would like to see examples of where it's needed, because I slightly suspect that wrapping possibly-blocking operations in an exception handler that does something appropriate, along with ordinary 'mask', might be sufficient... But I expect to be proved wrong; I just haven't figured out how to prove myself wrong.

Take my threads package, I uploaded to hackage yesterday, as an example.

In Control.Concurrent.Thread.Group.fork...

Control.Concurrent.Thread.fork is a similar and simpler example of why nonInterruptibleMask is needed: http://hackage.haskell.org/packages/archive/threads/0.1/doc/html/src/Control... If an asynchronous exception is thrown during the 'putMVar res' any waiters on the thread will never be woken up. regards, Bas