Fix Shutdown race.

Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=http://dartbug.org/25351
R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/1ce512b69f5c6d331df585b93280a9978f939eb2

[zra, 2016-01-05 22:13:16]

zra@google.com changed reviewers:
+ asiva@google.com, turnidge@google.com

[zra, 2016-01-05 23:22:59]

Offline, we discussed instead making this per-isolate so that killing isolates
in other ways is safe w.r.t. spawn. I will do that, and ping this CL when it is
ready.

[zra, 2016-01-05 23:45:48]

zra@google.com changed reviewers:
+ iposva@google.com

[zra, 2016-01-06 21:05:20]

I have moved the outstanding spawn count to be per-isolate. PTAL.

[zra, 2016-01-06 21:08:12]

Description was changed from

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.
==========

to

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=25351
==========

[zra, 2016-01-06 21:09:04]

Description was changed from

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=25351
==========

to

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=https://github.com/dart-lang/sdk/issues/25351
==========

[zra, 2016-01-06 21:09:42]

Description was changed from

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=https://github.com/dart-lang/sdk/issues/25351
==========

to

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=http://dartbug.org/25351
==========

[siva, 2016-01-08 02:00:10]

The changes itself LGTM.

It is unfortunate that we have to use such a heavy handed wait/notify scheme to
ensure that the isolate create callback function does not see stale data. All
other fields of IsolateSpawnState are copied down except for this callback data,
I am beginning to wonder if it is worth having the embedder provide a copy
callback.

[Ivan Posva, 2016-01-08 04:44:50]

On 2016/01/08 02:00:10, siva wrote:
> The changes itself LGTM.
> 
> It is unfortunate that we have to use such a heavy handed wait/notify scheme
to
> ensure that the isolate create callback function does not see stale data. All
> other fields of IsolateSpawnState are copied down except for this callback
data,
> I am beginning to wonder if it is worth having the embedder provide a copy
> callback.

In discussion with Zach yesterday we were coming to the same conclusion that we
need to either request a copy when spawning or have a length parameter so that
the VM can create its own copy. The former is obviously preferable as it allows
making deep copies if necessary.

-Ivan

[zra, 2016-01-08 20:31:00]

Description was changed from

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=http://dartbug.org/25351
==========

to

==========
Fix Shutdown race.

This CL fixes a race during VM shutdown in which the embedder's
isolate creation callback is passed an invalid isolate data pointer.

BUG=http://dartbug.org/25351
R=asiva@google.com

Committed:
https://github.com/dart-lang/sdk/commit/1ce512b69f5c6d331df585b93280a9978f939eb2
==========

[zra, 2016-01-08 20:31:01]

Committed patchset #3 (id:40001) manually as
1ce512b69f5c6d331df585b93280a9978f939eb2 (presubmit successful).