From: Vladimir Davydov <vdavydov.dev@gmail.com> To: Serge Petrenko <sergepetrenko@tarantool.org> Cc: Georgy Kirichenko <georgy@tarantool.org>, tarantool-patches@freelists.org Subject: Re: [tarantool-patches] Re: [PATCH] Fix fiber_join() hang in case fiber_cancel() was called Date: Tue, 5 Feb 2019 12:00:42 +0300 [thread overview] Message-ID: <20190205090042.vjtymjg7vp52aaki@esperanza> (raw) In-Reply-To: <08B70EC3-6EA3-405B-964F-7C10B5BA62F3@tarantool.org> On Tue, Feb 05, 2019 at 09:28:01AM +0300, Serge Petrenko wrote: > > > > 4 февр. 2019 г., в 20:44, Vladimir Davydov <vdavydov.dev@gmail.com> написал(а): > > > >> > >> diff --git a/src/fiber.c b/src/fiber.c > >> index 6f3d0ab78..4dc6b3c5a 100644 > >> --- a/src/fiber.c > >> +++ b/src/fiber.c > >> @@ -392,9 +392,17 @@ fiber_join(struct fiber *fiber) > >> assert(fiber->flags & FIBER_IS_JOINABLE); > >> > >> if (! fiber_is_dead(fiber)) { > >> - rlist_add_tail_entry(&fiber->wake, fiber(), state); > >> > >> do { > >> + /* > >> + * In case fiber is cancelled during yield > >> + * it will be removed from wake queue by a > >> + * wakeup following the cancel. > >> + * Having multiple entries for the same fiber > >> + * doesn't hurt, since wakeup is executed only > >> + * once per fiber. > >> + */ > >> + rlist_add_tail_entry(&fiber->wake, fiber(), state); > > > > I don't quite like the idea that cancelling a fiber that is joining > > another fiber will have no effect until the other fiber has exited. > > Can't we break the loop if fiber_is_cancelled()? > > We can do that. But then we have to set FIBER_IS_JOINABLE to false > for the joined fiber so that it executes fiber_recycle(). Why should we? IMO the user should be free to kill a fiber executing fiber_join. If that happens, the joinable fiber shouldn't be collected until another fiber joins it successfully. This would be consistent with pthread_join behavior. > Otherwise it will leak. Is it ok?
next prev parent reply other threads:[~2019-02-05 9:00 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-04 13:51 Serge Petrenko 2019-02-04 17:44 ` Vladimir Davydov 2019-02-05 6:28 ` [tarantool-patches] " Serge Petrenko 2019-02-05 9:00 ` Vladimir Davydov [this message] 2019-02-05 15:02 ` Serge Petrenko
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