RFR: JDK-8319120: Unbound ScopedValue.get() throws the wrong exception

[Alan Bateman]

On Mon, 30 Oct 2023 15:57:23 GMT, Andrew Haley <aph at openjdk.org> wrote:

> The bug here is a thinko in `ScopedValue.scopedValueBindings()`.
> 
> If the JVM runs out of resources, we throw a `VirtualMachineError`. Running out of resources can happen at almost any time, and can happen while `ScopedValue`'s internal structures are being modified, leaving them in an inconsistent state. We detect when a `VirtualMachineError` happens and walk the stack to find the most-recent set of `ScopedValue` bindings.
> 
> When we crate a new `Thread`, we push a sentinel frame onto the stack that we can find in the case that we threw a `VirtualMachineError`. Threads created by the native invocation interface (rather than by Java threads) don't have that sentinel, so a search for it returns null. Therefore, in the rare cases where we have to do a stack walk, we must check for both `NEW_THREAD_BINDINGS` (the sentinel) and `null`. We weren't doing that, we were only checking for null.

test/jdk/java/lang/ScopedValue/UnboundValueTest.java line 4:

> 2: 
> 3: /*
> 4:  * @test

It might be better to name the test something like UnboundValueAfterOOME or something better, only because it's not a unit test for all unbound value cases.

You'll need to add a copyright header to the test. Also might be useful to add `@bug 8319120`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16422#discussion_r1376484429