Data Races
A data race is a situation, in which at least two threads access a shared variable at the same time. At least one thread tries to modify the variable.
If your program has a data race, it has undefined behaviour. This means all outcomes are possible and therefore, reasoning about the program makes no sense anymore.
Let me show you a program with a data race.
1 // addMoney.cpp
2
3 #include <functional> 4 #include <iostream> 5 #include <thread> 6 #include <vector> 7
8 struct Account{
9 int balance{100};
10 };
11
12 void addMoney(Account& to, int amount){
13 to.balance += amount;
14 }
15
16 int main(){
17
18 std::cout << std::endl;
19
20 Account account;
21
22 std::vector<std::thread> vecThreads(100);
23
24
25 for (auto& thr: vecThreads) thr = std::thread(addMoney, std::ref(account...
