A <em>goroutine</em> is a lightweight thread of execution.

```cilk
#include <stdio.h>
#include <cilk/cilk.h>
#include <unistd.h>

void f(const char *from) {
    for (int i = 0; i < 3; i++) {
        printf("%s : %d\n", from, i);
    }
}

int main() {
    // Suppose we have a function call f(s). Here’s how we’d call that in the usual way, running it synchronously.
    f("direct");

    // To invoke this function in a goroutine, use cilk_spawn. This new goroutine will execute concurrently with the calling one.
    cilk_spawn f("goroutine");

    // You can also start a goroutine for an anonymous function call.
    cilk_spawn [&]{
        printf("going\n");
    }();
  
    // Our two function calls are running asynchronously in separate goroutines now. Wait for them to finish
    sleep(1);
    printf("done\n");

    return 0;
}