Integrated: 8349927: Waiting for compiler termination delays shutdown for 10+ ms

[Aleksey Shipilev]

On Wed, 12 Feb 2025 19:13:18 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> See bug for extended description. This PR reworks the shutdown waiting mechanism in three ways: 
>  1. Use exponential backoff with very small wait time at the start, to catch compiler threads earlier.
>  2. Avoid timed-wait on Monitor, when a sleep would suffice.
>  3. Track the time accurately, so we are not at the mercy of sleep/wait accuracy.
> 
> I originally found this issue when studying Leyden performance, but it affects mainline in the same way. For example, JavacBenchApp from Leyden shows we consistently save ~10ms of round-trip time:
> 
> 
> Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -Xmx512m -Xms512m -XX:+UseParallelGC \
>  -cp JavacBenchApp.jar JavacBenchApp 1 1
> 
> # Before
>   Time (mean ± σ):     495.4 ms ±   2.4 ms    [User: 1321.2 ms, System: 110.4 ms]
>   Range (min … max):   489.8 ms … 502.6 ms    100 runs
> 
> # After
>   Time (mean ± σ):     485.4 ms ±   2.7 ms    [User: 1318.9 ms, System: 110.3 ms]
>   Range (min … max):   479.8 ms … 494.3 ms    100 runs
> 
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `tier1`
>  - [x] Linux AArch64 server fastdebug, `all`

This pull request has now been integrated.

Changeset: d8fcd43a
Author:    Aleksey Shipilev <shade at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/d8fcd43a24a989b71ed30945fda78541c1e42b60
Stats:     31 lines in 1 file changed: 15 ins; 4 del; 12 mod

8349927: Waiting for compiler termination delays shutdown for 10+ ms

Reviewed-by: kvn, dholmes

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PR: https://git.openjdk.org/jdk/pull/23593