#14310: Assertion triggered by STM invariant. -------------------------------------+------------------------------------- Reporter: mbw | Owner: (none) Type: bug | Status: patch Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4065, Wiki Page: | Phab:D4067 -------------------------------------+------------------------------------- Comment (by bgamari): fryguybob had some very useful feedback on these patches. It seems like there is yet another issue: the assertion in `raiseAsync` is itself wrong (as I suspected in comment:5). To summarize: Normal top-level STM transactions (e.g. initiated by an `atomically` call in Haskell) by definition should have `enclosing_trec == NO_TREC`. The `ATOMICALLY_FRAME` handler in `raiseAsync` checks this invariant with an assert. In the case of nested transactions initiated by `orElse` we will hit a `CATCH_RETRY_FRAME` before hitting an `ATOMICALLY_FRAME`, avoiding this assertion. However, in the case of nested transactions started by the STM machinery for the purpose that we are checking invariants we have no such `CATCH_RETRY_FRAME`. `stg_atomically_frame` just pushes an `ATOMICALLY_FRAME`. Since this frame will have `enclosing_trec != NO_TREC`, this trips the assertion. Instead we should be asserting something like, {{{#!c DEBUG_ONLY(StgAtomicallyFrame *atomically = (StgAtomicallyFrame *) frame); ASSERT(tso->trec->enclosing_trec == NO_TREC || atomically->next_invariant_to_check != END_INVARIANT_CHECK_QUEUE); }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14310#comment:17 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler