RFR: 8359827: Test runtime/Thread/ThreadCountLimit.java should run exclusively [v3]

[SendaoYan]

On Tue, 22 Jul 2025 12:13:44 GMT, David Holmes <dholmes at openjdk.org> wrote:

> If the ulimit setting only affects the sub-shell then it can't cause other concurrent tests to hit the limit and fail to create threads!

Maybe some of my previous statements have caused some misunderstandings.
The usage of ulimit in this testcase will not cause other concurrent tests to hit the limit, but will cause this test itself do not have enough user processes to start the java.
On the huge core number machine, every test will create more JIT compiler threads and more GC work threads. So when this test run with other tests simultancely, we can see this test can not start subprocess java with prefix "ulimit -u", the subprocess java report `Failed to start thread "GC Thread#0"`, because the subprocess has limited by "ulimit -u 4096", and the user processes resources maybe has been occupied by other tests which run simultancely. And the other tests run normally, because they do not have 'ulimit -u' explicitly.

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PR Comment: https://git.openjdk.org/jdk/pull/26401#issuecomment-3102544916