Hi Günter Günther Schmidt wrote: > Hi, > > in an application of mine I start a long-running operation in a thread via > forkIO so that the UI process doesn't get blocked. > It just so happens, that the long-running process also takes the CPU to > nearly 100% while it runs. > > During that time the run-time system does *not* switch back and forth > between the UI-process and the long-running task, it seems that the UI > process only gets woken up *after* the high CPU thread finishes completely. > > To the effect of course that it makes no difference at all to the UIs > responsiveness whether I use forkIO or not. > > The long running process is pretty atomic, it's a single query to the > database which takes up to a minute to complete so I don't see a chance to > squeeze a "mainIteration" in there.
It could be the database library, as it may use unsafe foreign calls. Unsafe foreign calls blocks all other threads, even if you compile with the -threaded option. See http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Concurrent.html#4 . I cannot claim to know how all Haskell database libraries are implemented, but at least some of them use unsafe foreign calls. So which database library is you using? > > What can I do? If the problem has to do with unsafe foreign calls, then you can implement the database calls in a separate process. Not the easiest options, but I can think of no other. > > Günther > /Mads Lindstrøm _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe