RFR: JDK-8319662 ForkJoinPool trims worker threads too slowly

[Viktor Klang]

On Sun, 19 Nov 2023 17:36:01 GMT, Doug Lea <dl at openjdk.org> wrote:

> This update cascades timeouts to trim subsequent workers after the first  keepAlive inactive period.

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 2140:

> 2138:             Thread.interrupted();               // clear for next park
> 2139:             if (deadline != 0L &&               // try to trim on timeout
> 2140:                 deadline - System.currentTimeMillis() < TIMEOUT_SLOP) {

Since `currentTimeMillis()` is fetched from system time, I think it might be more appropriate to use nanoTime() to track delays.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16725#discussion_r1399055155