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正如你看到的,當我刪除mt.lock()和mt.unlock,結果比50000什麼的線程競爭infulence?
爲什麼小了?居然會發生什麼?如果你能爲我解釋,我將非常感激。
#include <iostream>
#include <thread>
#include <vector>
#include <mutex>
using namespace std;
class counter{
public:
mutex mt;
int value;
public:
counter():value(0){}
void increase()
{
//mt.lock();
value++;
//mt.unlock();
}
};
int main()
{
counter c;
vector<thread> threads;
for(int i=0;i<5;++i){
threads.push_back(thread([&]()
{
for(int i=0;i<10000;++i){
c.increase();
}
}));
}
for(auto& t:threads){
t.join();
}
cout << c.value <<endl;
return 0;
}