#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): OK great! To summarize: Whenever the RTS has been inactive for idleGCDelayTime, the idle timer fires and calls `wakeUpRts()`, which in turn calls `ioManagerWakeup()`, which in turn writes a byte (or a few) to a file descriptor (stored in the `io_manager_wakeup_fd` variable) registered by the TimerManager and on which the TimerManager will wait. (Note that the write will only occur if the file descriptor is non-negative.) When the RTS shuts down, it shuts down the TimerManager, and in this process the file descriptor stored in `io_manager_wakeup_fd` is closed. In the error case, the idle timer fires after the close of the file occurs, and then the `write()` call in `ioManagerWakeup()` fails and the aforementioned error message gets printed. I think the solution in the Control.hs modification is solid; it addresses the problem without silently ignoring other error conditions due to the `write()`. Another solution might be to disable the idle timer once the program shutdown sequence has started, though that could have more far- reaching effects, so I think the minor Control.hs modification is good for now. I'll clean it up, add a comment or two, and then make a patch. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9722#comment:27 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler