Comment #11 on issue 91 by elias.kunnas: DynamicLog causes xmonad to hang when the output pipe is full http://code.google.com/p/xmonad/issues/detail?id=91 I've been researching this bug for a long-ish time. It might be that the way EPIPE is handled by xmonad or GHC has some relevance to this, but it's very likely not the primary cause. I've been rather exhaustively trying different combinations of EPIPE handlers in xmonad (including not handling it at all, setting arbitrary handlers and using the default handler), and nothing so far has affected the buggy behaviour that I'm able to reproduce ~30% of the time with the config on comment 5. One fairly sure sign that GHC itself has much to do with this, although I haven't been able to replicate the behaviour outside xmonad, is that even setting a timeout to each log write will still cause xmonad to hang. I mentioned this in #haskell@freenode and it turns out people have experienced similar issues with fdRead (assuming pipe writes are ultimately calling that, though I haven't been able to follow the code to this point). In http://upcycle.it/~blackh,/Server.hs, the issue with fdRead was fixed apparently by adapting the code from ghc-6.12. Since this fixes the issue with fdRead, it seems it may well be the case that just using GHC-6.12 would fix pipe writes as well (so presumably fdWrite). It seems the reason for this is that up to GHC-6.10, fdRead (and presumably fdWrite? Haven't been able to verify this yet) were implemented using unsafe ccalls whereas they now use safe ones. Following the discussion on #haskell, the unsafe ccalls might then starve the threads of their process, which would be consistent with seeing 'timeout' not halting the IO writes. -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings