RFR: 8349927: Waiting for compiler termination delays shutdown for 10+ ms [v2]

[Aleksey Shipilev]

On Thu, 13 Feb 2025 08:28:55 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`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update src/hotspot/share/runtime/vmOperations.cpp
>   
>   Co-authored-by: David Holmes <62092539+dholmes-ora at users.noreply.github.com>

Thanks! Testing looks fine here, so I am integrating.

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PR Comment: https://git.openjdk.org/jdk/pull/23593#issuecomment-2657602580