On Sun, 26 Oct 2025 14:17:33 GMT, Alan Bateman <[email protected]> wrote:

> This test will need re-work.

The end-goal of this test was to verify that the implementation correctly 
guarded against races during shutdown which it manged to test. So to that end 
I'm not sure this particular test needs re-work as it correctly manages to run 
Java code that races on this method during VM shutdown. However, if I 
understand your comment you are suggesting that we should (1) simplify how the 
test is invoked (2) add a test for checking that the value is monotonically 
increasing. For the latter I did not add such test as we in the end rely 
on`os::thread_cpu_time`.

> `GC cpu time is <= process cpu time`

I think we are at the mercy of how well the underlying OS update thread CPU 
time. I know that for extremely short-lived processes, the accounting for CPU 
time may be less reliable at least on Linux. In general, can Hotspot make any 
guarantee about CPU time for threads vs process CPU time?

> What is the reason for launching a sub-process? 

I looked at other tests how they launched tests for different GCs and that's 
the way I found to achieve that. If `@requires` is another way and is the 
preferred one I can change.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27537#discussion_r2463870835

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