RFR: 8336299: Improve GCLocker stall diagnostics [v4]

[Thomas Schatzl]

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

Changes requested by tschatzl (Reviewer).

src/hotspot/share/gc/shared/gcLocker.cpp line 50:

> 48:   public:
> 49:     GCLockerTimingDebugLogger(const char* log_message) :
> 50:       _log_message(log_message) {

Indentation of the entire class is one level too deep; the first `private` visibility specifier can be ommitted.
There are two spaces before `_log_message`.

src/hotspot/share/gc/shared/gcLocker.cpp line 53:

> 51:         assert(_log_message != nullptr, "GC locker debug message must be set.");
> 52:         _start = Ticks::now();
> 53:       }

I think this `}` should align with the method name, i.e. the body of this constructor seems to be nested one level too deep.

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PR Review: https://git.openjdk.org/jdk/pull/20277#pullrequestreview-2214937023
PR Review Comment: https://git.openjdk.org/jdk/pull/20277#discussion_r1701456382
PR Review Comment: https://git.openjdk.org/jdk/pull/20277#discussion_r1701458868