NoLock.cpp

//to use standard input/output
#include <iostream>
//to use ofstream
#include <fstream>
//to use thread class
#include <thread>
//to use mutex lock
#include <mutex>
//to use vector
#include <vector>
//to calculate running time
#include <windows.h>
//THREADNUM == number of max thread to calculate
#define THREADNUM 256
using namespace std;


//save data in csv foramt
ofstream out("noLock.csv");

//critical section
static int count = 0;

//mutex lock class
mutex mtx_lock;


//function that increase counter
/*
	조건 변화에 따른 내용 구현은 모두 이 함수 안에서 이루어집니다.
*/

void counterIncrease() {
	for (int i = 0; i<1000000; i++) {
		::count++;
	}
}

int main() {
	//thread Array to keep threads
	vector<thread> threadArr;

	int beforeTime = 0;
	// increase thread 1 to THREADNUM(==MaxThreads)
	for (int nowThread = 1; nowThread <= THREADNUM; nowThread++) {
		int sumTime = 0;
		//repeat repeatTime Times for each thread
		for (int repeatTime = 0; repeatTime < 100; repeatTime++) {
			//clear critical section
			::count = 0;
			//clear thread vector
			threadArr.clear();
			//init begin Time
			int beg = GetTickCount();

			//init N threads and push back into threadArray vector
			for (int i = 0; i < nowThread; i++) {
				threadArr.push_back(thread(&counterIncrease));
			}

			//wait for all thread finish their work
			for (thread & th : threadArr) {
				if (th.joinable()) {
					th.join();
				}
			}
			
			//check end time
			int end = GetTickCount();
			//calculate execution time
			int msec = end - beg;
			
			//save execution time
			sumTime += msec;
		}

		//calculate average execution time
		int avgTime = sumTime/100;

		//print Number of thread & average execution time
		cout << "num of thread = " << nowThread << "\t" << "time : " << avgTime << "ms" << "\t";
		
		//print gap compare to before time (n-1 thread execution time) & calculated counter (critical section)
		cout << "(" << avgTime - beforeTime <<")"<< "\t" << "count =" << ::count << "\t";

		//print if (counter is same as expected == true), else == false
		if (::count == nowThread * 1000000) {
			cout << "True" << endl;
		}
		else {
			cout << "False" << endl;
		}

		//also save same data in csv file

		out << nowThread << "," << avgTime << "," << avgTime - beforeTime << "," <<::count << ",";

		if (::count == nowThread * 1000000) {
			out << "True" << endl;
		}
		else {
			out << "False" << endl;
		}
		beforeTime = avgTime;

	}

	return 0;
}