[jdk20] RFR: 8298400: Virtual thread instability when stack overflows

[Dean Long]

On Thu, 12 Jan 2023 12:12:42 GMT, Ron Pressler <rpressler at openjdk.org> wrote:

> The stack overflow is detected in the native code and a pending exception is set, but it is not thrown.
> 
> Additionally, the stack overflow detection is changed use StackOverflow::shadow_zone_safe_limit rather than StackOverflow::stack_overflow_limit.

I'm wondering if both gen_continuation_enter and gen_continuation_yield can handle exceptions the same way.  Have _yield set an exception_offset, so there is no overhead when there is no exception.  Then if _yield can use StubRoutines::forward_exception_entry, then _enter probably can too.

It seems like this exception handling problem would have existed before JDK-8292584, when _yield was a stub.  At least I'm not aware of stubs have automatic exception handling.

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PR: https://git.openjdk.org/jdk20/pull/101