#7170: Foreign.Concurrent finalizer called twice in some cases -------------------------------------+------------------------------------- Reporter: joeyadams | Owner: niteria Type: bug | Status: patch Priority: high | Milestone: 7.6.1 Component: Core Libraries | Version: 7.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime crash | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | ffi/should_run/7170 | Blocking: | Differential Revisions: D921 -------------------------------------+------------------------------------- Comment (by Simon Marlow ): In [changeset:"dfdc50d666498c5a1118557d67209fe067c61cc1/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="dfdc50d666498c5a1118557d67209fe067c61cc1" Don't call DEAD_WEAK finalizer again on shutdown (#7170) Summary: There's a race condition like this: # A foreign pointer gets promoted to the last generation # It has its finalizer called manually # We start shutting down the runtime in `hs_exit_` from the main thread # A minor GC starts running (`scheduleDoGC`) on one of the threads # The minor GC notices that we're in `SCHED_INTERRUPTING` state and advances to `SCHED_SHUTTING_DOWN` # The main thread tries to do major GC (with `scheduleDoGC`), but it exits early because we're in `SCHED_SHUTTING_DOWN` state # We end up with a `DEAD_WEAK` left on the list of weak pointers of the last generation, because it relied on major GC removing it from that list This change: * Ignores DEAD_WEAK finalizers when shutting down * Makes the major GC on shutdown more likely * Fixes a bogus assert Test Plan: before this diff https://ghc.haskell.org/trac/ghc/ticket/7170#comment:5 reproduced and after it doesn't Reviewers: ezyang, austin, simonmar Reviewed By: simonmar Subscribers: bgamari, thomie Differential Revision: https://phabricator.haskell.org/D921 GHC Trac Issues: #7170 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7170#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler