On Wed, Feb 22, 2023 at 6:43 PM Xiangdong Ji <xiangdong...@gmail.com> wrote: > > Looks like the print* helper functions may run into deadlocks if the printer > Goroutine is rescheduled to a different M to execute 'printunlock' as the "if > mp.printlock==0" checking is likely to fail if M has changed.
Have you seen this happen? It ought to be impossible, because printlock increments mp.locks. When mp.locks is not zero the M can't be preempted and the goroutine can't block. Ian > Wondering is it intentional behavior? As print* are (almostly if not always) > used in runtime during STW or guarded by high level locks. > > I didn't figure out how to produce a deadlock by user testcase, but the > change below could easily deadlock 'go_bootstrap' when running > './src/make.bash'. > > A similar issue was opened in https://github.com/golang/go/issues/54786, but > no follow-up for months. > > Thanks. > > ``` > diff --git a/src/runtime/mgcsweep.go b/src/runtime/mgcsweep.go > index 6ccf090ac5..3336823dc0 100644 > --- a/src/runtime/mgcsweep.go > +++ b/src/runtime/mgcsweep.go > @@ -155,6 +155,7 @@ func (a *activeSweep) begin() sweepLocker { > return sweepLocker{mheap_.sweepgen, false} > } > if a.state.CompareAndSwap(state, state+1) { > + println("activeSweep.begin, old:", state, ",new:", > state+1) > return sweepLocker{mheap_.sweepgen, true} > } > } > @@ -172,6 +173,7 @@ func (a *activeSweep) end(sl sweepLocker) { > throw("mismatched begin/end of activeSweep") > } > if a.state.CompareAndSwap(state, state-1) { > + println("activeSweep.end, old:", state, ",new:", > state-1) > if state != sweepDrainedMask { > return > } > ``` > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/e48221e3-0709-49e1-8cbd-314044558c56n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcUYQMzXFZ-Bj16LrMwPyx4GgDGW7zmdX3fq4ccpguJrzQ%40mail.gmail.com.
