Hello, How does forkIO (forkOS) and par interact with one another? Here is why I ask. I have a GUI application that has something like this: th <- forkIO (guiCode + longRunningPureSerialCode) Later, a user interaction invokes killThread th and the guiCode plus the longRunningPureSerialCode suspends quite nicely. Now I have th <- forkIO (guiCode + longRunningPureParallelCode) Later a user interaction invokes killThread th again but I have observed under 6.10.4 that not all is suspended. From what I have observed, I believe that if longRunningPureParallelCode = ... 1stPart `par` 2ndPart ... the 2ndPart is suspended by killThread th along with the guiCode, and the 1stPart happily continues calcualting. (I believe this is correct but it could be the other way around.) For my little application, having everything suspend would have been nice, but that's my app. So, under ghc, how is forkIO (forkOS) and par supposed to operationally interact with one another? Cheers, - Marcus