gistfile1.txt

struct ThreadTestData 
{
	HANDLE hEvent;
	SRWLOCK SRWLock = {};
	LONG numThreads = 1;
	LONG readCounter = 0;

	void EndThread()
	{
		if (!InterlockedDecrementNoFence(&numThreads))
		{
			if (!SetEvent(hEvent)) __debugbreak();
		}
	}

	void DoStuff()
	{
		AcquireSRWLockShared(&SRWLock);

		ULONG n = 0, m = 0, k = InterlockedDecrementNoFence(&readCounter);

		while (readCounter)
		{
			switch (NtYieldExecution())
			{
			case STATUS_SUCCESS:
				n++;
				break;
			case STATUS_NO_YIELD_PERFORMED:
				m++;
				break;
			default:
				__debugbreak();
			}
		}

		ReleaseSRWLockShared(&SRWLock);

		DbgPrint("%x> %x/%x\n", k, n, m);

		EndThread();
	}

	static ULONG WINAPI _S_DoStuff(PVOID data)
	{
		reinterpret_cast<ThreadTestData*>(data)->DoStuff();
		return 0;
	}

	void Test(ULONG n)
	{
		if (hEvent = CreateEventW(0, 0, 0, 0))
		{
			AcquireSRWLockExclusive(&SRWLock);

			do 
			{
				numThreads++;
				readCounter++;

				if (HANDLE hThread = CreateThread(0, 0, _S_DoStuff, this, 0, 0))
				{
					CloseHandle(hThread);
				}
				else
				{
					readCounter--;
					numThreads--;
				}

			} while (--n);

			ReleaseSRWLockExclusive(&SRWLock);

			EndThread();

			if (WAIT_OBJECT_0 != WaitForSingleObject(hEvent, INFINITE))
			{
				__debugbreak();
			}

			CloseHandle(hEvent);
		}
	}
};

void ep()
{	
	ThreadTestData data;
	data.Test(8);
}

/*-- for 8 threads

3> 9/e0
0> 0/0
4> 0/30d
1> 5/6
6> 0/3ba
2> 4/1f
5> 1/32c
7> 7/38d

--*/

/*-- for 64 threads

38> 2b/0
32> 29/0
d> d/0
24> 29/0
25> 27/0
22> 26/0
0> 0/0
28> 2a/0
3e> 2e/1c
39> 2d/0
3c> 2b/0
3d> 2d/13
3f> 2d/1
37> 2b/0
33> 2b/0
34> 2c/0
3b> 2c/0
36> 2c/0
2c> 29/0
31> 2b/0
2f> 2c/0
26> 2b/0
35> 2b/0
27> 29/0
30> 2b/0
2e> 2b/0
1e> 28/0
2d> 29/0
20> 27/0
21> 29/0
1> 2/0
3a> 2d/0
2b> 2c/0
1d> 26/0
1c> 23/0
1b> 23/0
19> 1f/0
18> 1c/0
2a> 29/0
17> 1c/0
15> 18/0
1a> 22/0
16> 1b/0
12> 15/0
14> 17/0
13> 15/0
e> 10/0
11> 12/0
f> 10/0
10> 12/0
23> 27/0
c> d/0
b> c/0
9> a/0
8> 9/0
a> b/0
7> 8/0
4> 5/0
1f> 26/0
5> 5/0
6> 7/0
2> 3/0
3> 4/0
29> 2b/0

--*/

/*-- for 13 threads

5> 19/37
4> 13/0
0> 0/0
c> 1e/35
6> 1f/3b
8> 25/38
b> 27/4a
a> 26/5e
7> 1e/35
1> 5/0
3> 10/0
9> 21/62
2> d/0
--*/