David Kastrup <d...@gnu.org> writes: > David Kastrup <d...@gnu.org> writes: > >> Jonas Hahnfeld via Discussions on LilyPond development >> <lilypond-devel@gnu.org> writes: >> >>> Am Donnerstag, dem 25.11.2021 um 08:40 +0100 schrieb Jonas Hahnfeld via >>> Discussions on LilyPond development: >>>> Am Mittwoch, dem 24.11.2021 um 23:01 +0100 schrieb Han-Wen Nienhuys: >>>> > On Wed, Nov 24, 2021 at 8:13 PM Jonas Hahnfeld via Discussions on >>>> > LilyPond development <lilypond-devel@gnu.org> wrote: >>>> > > Assuming no major problems are found, we could then move completely to >>>> > > Guile 2.2 and do releases without GUB. Both steps still require a bit >>>> > > of work; I'm relatively sure there is still a GC related issue causing >>>> > > (very rare) crashes with Guile 2.2 >>>> > >>>> > can you say more about this? >>>> >>>> Not really: I remember weird crashes with dumps that were not >>>> immediately obvious. >>> >>> It's relatively reproducible, I get it every 2nd-3rd time for full >>> 'make doc's. Looking at the core dump, it's crashing in >>> System::derived_mark when marking all_elements_ because the std::vector >>> has garbage in its size field (it was probably freed). What I don't >>> understand is how that can happen since the only way of setting >>> all_elements_ is in System::init_elements where the originating SCM is >>> also protected... >> >> My guess is that std::vector is not freed but rather not initialised. >> That kind of thing is what the Preinit class is supposed to prevent, but >> System does not use it. >> >> Note also that all_elements_ is initialised to nullptr only _after_ >> garbage collection has already been activated: the in-class >> initialisation syntax makes it easier to gloss over initialisation order >> (which is not changed). >> >> I'll try GC-proofing System. Only time will tell whether this makes a >> difference and/or whether other problems remain. > > Somewhat embarrassingly, it would not appear that anything protects > *all_elements_ as such (only its elements are protected in > System::derived_mark). That would be kind of a WTF even with Guile-1.8 > .
Well... System::init_elements has set_object (this, "all-elements", scm_arr); So *all_elements_ is protected as part of being a Spanner. As long as the spanner has not committed suicide (when it drops its object list). If it has committed suicide but not been collected yet, *all_elements_ may be collected before the System itself. This is garbage. -- David Kastrup
