#9377: forkProcess unnecessarily sets wait_foreign in hs_exit_ -------------------------------------+------------------------------------- Reporter: edsko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: Phab:D99 -------------------------------------+------------------------------------- During normal course of action in `real_main` a process is terminated with a call to {{{#!hs shutdownHaskellAndExit(exit_status, 0 /* !fastExit */); }}} which is defined as {{{#!hs void shutdownHaskellAndExit(int n, int fastExit) { if (!fastExit) { // even if hs_init_count > 1, we still want to shut down the RTS // and exit immediately (see #5402) hs_init_count = 1; // we're about to exit(), no need to wait for foreign calls to return. hs_exit_(rtsFalse); } stg_exit(n); } }}} However, when we call `forkProcess`, the child process does ''not'' terminate in this manner, but instead calls {{{#!hs hs_exit(); // clean up and exit stg_exit(EXIT_SUCCESS); }}} instead, where `hs_exit` is defined as {{{#!hs void hs_exit(void) { hs_exit_(rtsTrue); // be safe; this might be a DLL } }}} Crucially, this means that, unlike the parent, the child process ''does'' wait for foreign calls to be terminated (it calls `hs_exit_` with `rtsTrue` instead of `rtsFalse`). I don't see a reason why the child process should terminate in a different manner to the parent, so I propose to change this so that `forkProcess` calls `shutdownHaskellAndExit`, just like `real_main` does. Incidentally, this is the immediate cause for https://ghc.haskell.org/trac/ghc/ticket/9284 , although the patch proposed in this ticket is not sufficient to solve the problems with termination of the I/O manager in the general case (but I will let Andreas explain that in more detail :). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9377 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler