RFR: 8359820: Improve handshake/safepoint timeout diagnostic messages [v7]

[David Holmes]

On Mon, 28 Jul 2025 10:10:59 GMT, Anton Artemov <duke at openjdk.org> wrote:

>> Hi, please consider the following changes:
>> 
>> The problem in the issue description is not a problem by itself, the behavior is not unexpected, but it is somewhat difficult to find out what caused SIGILL to be fired.
>> 
>> We propagate this information from `handshake::handle_timeout()` to `VMError::report()` with a help of a global variable.  The same mechanism is used to address a similar issue in the safepoint timeout handler. 
>> 
>> Tested in tiers 1-3.
>
> Anton Artemov has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - 8359820: Addressed reviewer's comments
>  - 8359820: Addressed reviewer's comments

src/hotspot/share/utilities/vmError.cpp line 108:

> 106: const intptr_t    VMError::segfault_address = pd_segfault_address;
> 107: volatile intptr_t VMError::_handshake_timeout_thread = p2i(nullptr);
> 108: volatile intptr_t VMError::_safepoint_timeout_thread = p2i(nullptr);

Sorry there was a typo in my suggestion - it should be `timed_out` to match the function names. (Or change the functions to use `timedout` - I tend to use `timedout` as a single "word" in these contexts.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26309#discussion_r2250716621