[MyPerf4J-101] Fix flaky test testMultiThread4HighRace and testMultiThread4LowRace #101

[CaseyPan]

What is the purpose of the change

Fix #101

Brief ChangeLog

1. Test Overview:
   Location: Myperf4j-Base/util/concurrent/AtomicIntHashCounterTest.java
   Test : testMultiThread4HighRace and testMultiThread4LowRace

   The two test are designed to assess the behavior of a multi-threaded scenario with varying levels of contention, and they use random parameters to perform a large number of iterations to test the stability and correctness of the tested code.

2. Reason of flakiness:
   ExecutorService newFixedThreadPool(int nThreads) method creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue. And it will throw error message IllegalArgumentException if nThreads <= 0.
   The author initially set the threadCnt to availableProcessors() - 2 to maybe avoid occupying too many computing resources. However, when the machine we use has less than 2 processors, an error will arise.

3. Changes:

• Introduced a new variable availableThreads to store the number of available processors.
• Added conditional check to threadCnt to handle cases with different number of available processors.
  • If the machine has less than 2 available processors, it throws an error message indicating that multithreading is not supported
  • If the machine has 2 or 3 available processors, it use 2 threads for testing.
  • For all other cases, it use availableThreads - 2 threads, which is consistent with the original code.

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[yashdeep97]

Thanks for adding the thorough PR description (Explains the changes really well!)
One minor change - Could you please update the "Purpose of the change"? Currently it says "Fix #XXX"

[yashdeep97]

Could you please elaborate on why you chose to assign threadCnt = 2 when there are 2 or 3 available processors?
I think the authors might have an issue if both processors get used since their primary motive was to keep 2 processors available for other computing tasks.
In case of 3 available threads, maybe we can assign just one thread since that is what the authors initially intended? (However, I'm not 100% sure if this is the best approach)

[yesh385]

Could you please update the PR by addressing the above comments?