commit 7f38a7965eb11fe4ac79a7aab83c84b82ed8c816
author Martin Kustermann <kustermann@google.com> Tue May 09 13:01:37 2023 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue May 09 13:01:37 2023 +0000
tree c28a27c8f73adba7fd988bb4974ef3e14b32299a
parent 1f2e131d87580249064ddae27a4966cf34ba8350

[vm] Ensure reload safepoint operation sends OOBs to all non-parked mutators

The reload safepoint operation mechanism will send out-of-band message
to all isolates that are not already at-reload-safepoint.

It identified all such threads by iterating the active threads list,
filtering those that are not at-reload-safepoint and those with an
active isolate (i.e. `thread->isolate() != nullptr`).

This `thread->isolate() != nullptr` condition isn't quite
correct. A mutator may temporarily run under a [NoActiveIsolateScope] to
make the `Isolate::Current()` unavailable to code that shouldn't depend
on isolates (e.g. GC and Compiler do that) or may even have the
incorrect isolate on it (e.g. Debugger Service notifications).

So if one thread triggers a [ReloadSafepointOperation] and another
thread is under a [NoActiveIsolateScope] it will not get the OOB message
and therefore not get interrupted to check-in.

This has caused flaky timeouts of `vm/dart/isolates/reload_active_stack_test`
- as this test runs isolates with active stack without going back
to event loop (which would check into reload operations).

Closes https://github.com/dart-lang/sdk/issues/52135

TEST=Updated vm/cc/Reload_NotAtSafepoint for regression test
TEST=Fixes flaky timeouts of vm/dart/isolates/reload_active_stack_test

Change-Id: Ib407c42aa97798ac994aff3bce263da79b83666a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/302320
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>