Handle Possibility that Parent Scope is Closed #3912
Merged
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Resolves #3910.
In
FiberContext#fork
there is an implicit assumption thatunsafeEnsure
will always succeed in adding a finalizer to the parent scope. However, that does not appear to always be the case. In particular, afterfork
is called but beforeunsafeEnsure
obtains a lock, a concurrent process could close the parent scope. Right now this causes a defect which this PR removes.In addition to this, I think we have a risk of not propagating interruption, because if the parent scope has already been closed we want to immediately interrupt the child fiber or possibly not begin executing it at all.