RFR: JDK-8301704: Shorten the number of GCs in UnloadingTest.java to verify a class loader not being unloaded

[Roger Riggs]

On Thu, 2 Feb 2023 20:09:22 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> `test/jdk/java/lang/invoke/defineHiddenClass/UnloadingTest.java` defines hidden classes and verify cases that a class loader is not unloaded using `ForceGC::wait`.    ForceGC::wait` defaults the timeout to 1000ms * jtreg timeout factor, which is designed to work well to expect an object being reclaimed, i.e. the boolean supplier returns true.   On the other hand, if the boolean supplier never returns true, the method returns after it timeouts which may be long depending on the timeout factor. 
> 
> This PR adds a variant of `ForceGC::wait` to take a timeout parameter and tests can specify the timeout to reduce the time it takes testing a strongly reachable object not being reclaimed.

test/lib/jdk/test/lib/util/ForceGC.java line 73:

> 71:      *     if did not complete after the specified waiting time.
> 72:      */
> 73:     public static boolean wait(BooleanSupplier booleanSupplier, long timeout) {

Can the method name be changed to make it clear the timeout is not scaled by the TIMEOUT factor.
(It would have been better if the original method name mentioned the timeout factor).
How about,  `waitNoMoreThan`.

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PR: https://git.openjdk.org/jdk/pull/12392