// https://godbolt.org/z/515dMo9Kx
#include <thread>
#include <barrier>
#include <iostream>
#include <vector>
long fib(long n) { return n<=1 ? n : fib(n-1)+fib(n-2); }
constexpr int anz = 8; // 8 workers
constexpr int max_n = 32; // calculate up to 32
std::vector<long> results(anz); // Buffer: space for 8 results
void output() { // Signaling function prints buffer
for (auto n : results) std::cout << n << ' ';
std::cout << '\n';
}
std::barrier ba{anz, output}; // always output after 8
void worker(std::stop_token st, int idx) {
// n = 0, 9, 17, 25, … ; 1, 10, 18, 26, …
for(int n = idx; n<max_n; n += anz) {
if(st.stop_requested()) return;
results[idx] = fib(n); // write result to buffer
ba.arrive_and_wait(); // wait until 8 threads are here
}
}
int main() {
std::vector<std::jthread> threads; // 8 Threads
for (int idx=0; idx<anz; ++idx) {
threads.emplace_back(worker, idx); // create thread with index
}
for (auto& t : threads) t.join(); // wait until all are done
}