[jdk16] RFR: 8258007: Add instrumentation to NativeLibraryTest [v2]

[Naoto Sato]

On Fri, 18 Dec 2020 23:34:04 GMT, Brent Christian <bchristi at openjdk.org> wrote:

>> This change adds some extra test output for NativeLibraryTest, primarily via an update to the ForceGC utility class.
>> 
>> It was observed that there was nothing preventing the Cleaner from cleaning the short-lived Object that ForceGC registers before await()/doit()/System.gc() is even called.
>> 
>> The new 'o' reference is kept alive until FoceGC.await() has been called.
>> 
>> We should find out a little more the next time NativeLibraryTest fails (or perhaps it won't fail anymore!)
>
> Brent Christian has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add sleep to ForceGC.await()

Looks good to me.

test/lib/jdk/test/lib/util/ForceGC.java line 48:

> 46:             for (int i = 0; i < 10; i++) {
> 47:                 System.gc();
> 48:                 System.out.format("doit %d: gc %d%n", iter, i);

Could be better to keep using println(), if performance is important.

-------------

Marked as reviewed by naoto (Reviewer).

PR: https://git.openjdk.java.net/jdk16/pull/53