#9722: ghcirun004 intermittently fails with ghc: ioManagerWakeup: write: Bad file descriptor -------------------------------------+------------------------------------- Reporter: ezyang | Owner: simonmar Type: bug | Status: patch Priority: high | Milestone: 7.10.1 Component: Runtime System | Version: 7.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime crash | Unknown/Multiple Blocked By: | Test Case: ghcirun004 Related Tickets: | Blocking: | Differential Revisions: Phab:D714 -------------------------------------+------------------------------------- Comment (by AndreasVoellmy): Thanks thomie! I think I see what is happening now: the TimerManager registers a file descriptor with the RTS for use by the `ioManagerWakeup()` function in `rts/posix/Signals.c`. When the TimerManager shuts down, it closes this file descriptor. I think there is a race condition where rts/Schedule.c calls `ioManagerWakeup()` after the TimerManager has shutdown. The TimerManager should only shutdown when the program is exiting, so it's probably safe to simply silently ignore the failing write, although this probably needs some review. In the meantime, I've modified `GHC/Event/Control.hs` to write `-1` to `io_manager_wakeup_fd` just before it closes the file descriptor. This should address the race condition. Can you compile your ghc with the attached Control.hs and check whether it makes the problem go away for you? Thanks! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9722#comment:25 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler