RFR: 8336299: Improve GCLocker stall diagnostics [v4]

[Albert Mingkun Yang]

On Thu, 1 Aug 2024 21:13:48 GMT, Neethu Prasad <nprasad at openjdk.org> wrote:

>> **Notes**
>> Adding logs to get more visibility into how fast a thread resumes from allocation stall. 
>> 
>> **Testing**
>> * tier 1, tier 2, hotspot_gc tests.
>> 
>> Example log messages
>> 
>> 1. Last thread exiting. Performing GC after exiting critical section. Thread "main" 0 locked.
>> 
>> 2. Thread exiting critical region Thread "main" 0 locked.
>> 
>> 3. Thread stalled by JNI critical section. Resumed after 586ms. Thread "Thread-0".
>> 
>> 4. Thread blocked to enter critical region. Resumed after 1240ms. Thread "SIGINT handler".
>
> Neethu Prasad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address formating issue and code clean up feedback

src/hotspot/share/gc/shared/gcLocker.cpp line 56:

> 54: 
> 55:     ~GCLockerTimingDebugLogger() {
> 56:       const Tickspan elapsed_time = Ticks::now() - _start;

Why is this outside the `if` logger-enabled check?

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PR Review Comment: https://git.openjdk.org/jdk/pull/20277#discussion_r1701374847