Fix thread-count runaway in GC/Scenarios/THDChaos test

[Copilot]

THDChaos intermittently fails with OutOfMemoryException from Thread.Start — the test creates hundreds of native threads in a burst, which exhausts resources on Arm32's constrained address space.

The bound on successor threads was also ineffective: iCounter is static, but the increment took lock(this), and every LivingObject has a different this. Increments were lost and the iCounter < iThrd check raced, so more threads were spawned than intended.

Changes

• livingobject.cs — IncreatCount uses Interlocked.Increment and returns the new value. The successor thread is started only when that increment reserved a slot, making the cap a genuine bound rather than a racy check:

  if( IncreatCount( ) <= ThdChaos.iThrd )
  {
      Thread Mv_Thread = new Thread( new ThreadStart (this.ThreadStart) );
      Mv_Thread.Start( );
  }

  The logging read of iCounter uses Volatile.Read.

• thdchaos.cs — caps iThrd at 5 on Arm32, consistent with how other thread-heavy tests are throttled there.

• Fixes Test failure: GC/Scenarios/THDChaos/thdchaos/thdchaos.cmd #130228

[Copilot]

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (1)

src/tests/GC/Scenarios/THDChaos/livingobject.cs:30

• The log uses a volatile read for the %100 check but prints iCounter via a separate non-volatile read. Since other threads can increment between the check and the write, this can print non-multiples of 100 (and generally misreport the value that triggered the log). Capture the value once and use it for both the modulo check and the output.

            if( Volatile.Read( ref iCounter )%100 == 0)
            {
                Console.Out.WriteLine( iCounter + " number of threads has been started" );
            }

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