Channels in Cilk

Cilk provides a different approach to concurrency compared to Go’s channels. Instead of channels, Cilk uses a work-stealing scheduler and cilk_spawn for parallel execution. Here’s an equivalent example using Cilk:

#include <cilk/cilk.h>
#include <iostream>
#include <atomic>

std::atomic<bool> flag(false);
std::string message;

void send_message() {
    message = "ping";
    flag.store(true, std::memory_order_release);
}

void receive_message() {
    while (!flag.load(std::memory_order_acquire)) {
        // Busy-wait
    }
    std::cout << message << std::endl;
}

int main() {
    cilk_spawn send_message();
    receive_message();
    cilk_sync;
    return 0;
}

In this Cilk example, we use atomic operations to simulate the synchronization behavior of channels.

We create an atomic boolean flag and a message string to pass data between threads.

The send_message function sets the message and signals its availability by setting the flag to true.

The receive_message function waits until the flag is set, then prints the message.

In the main function, we use cilk_spawn to create a new strand for send_message, which is similar to launching a goroutine in Go. The main strand continues with receive_message.

The cilk_sync at the end ensures that all spawned work is completed before the program exits.

When we run the program, the “ping” message is successfully passed from one strand to another.

$ g++ -fcilkplus channels.cpp -o channels
$ ./channels
ping

This example demonstrates how to achieve similar functionality to Go’s channels using Cilk’s parallel constructs and C++ atomic operations. While it’s not as straightforward as Go’s channel syntax, it provides a way to communicate between concurrent strands of execution in Cilk.