#4934: threadWaitRead works incorrectly on nonthreaded RTS ------------------------------------------------+-------------------------- Reporter: slyfox | Owner: Type: bug | Status: patch Priority: normal | Milestone: ⊥ Component: Runtime System | Version: 7.0.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Incorrect result at runtime | (amd64) Test Case: | Difficulty: Blocking: | Unknown | Blocked By: | Related Tickets: ------------------------------------------------+-------------------------- Comment (by slyfox):
Yes, please squash the patches and then I'll review.
Will do.
Not sure what you mean by "slightly change polling cycle to resume only descriptors with data available", don't we already do that?
I was a bit unclear. I meant: only in a case of '''select() == EBADF''' failure we always resumed all the blocked threads: https://ghc.haskell.org/trac/ghc/browser/ghc/rts/posix/Select.c#L295 {{{ if ( errno == EBADF ) unblock_all = rtsTrue; ... ready = unblock_all || FD_ISSET(tso->block_info.fd, &rfd); // [1] ... if (ready) pushOnRunQueue(&MainCapability,tso); }}} Current patchset only propagates exceptions early, but does not fix spurious resumes (as it was before). I propose to fix resume problem: {{{ --- ready = unblock_all || FD_ISSET(tso->block_info.fd, &rfd); +++ if (unblock_all) ready = fd_is_really_ready (fd); +++ else ready = FD_ISSET(tso->block_info.fd, &rfd); }}} It' won't be hard to implement on top of current patchset. Secondary '''select()''' can already provide all the info. Should I do it as a) a separate patch/ticket, b) merge into final result, c) don't touch it at all? Thanks! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/4934#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler