Channel Synchronization in Julia

Our example demonstrates how to use channels for synchronization between tasks. In Julia, we can achieve similar functionality using Channels and Tasks. Here’s the full source code:

using Printf

function worker(done::Channel{Bool})
    @printf("working...")
    sleep(1)
    println("done")
    
    # Send a value to notify that we're done
    put!(done, true)
end

function main()
    # Create a channel to notify on
    done = Channel{Bool}(1)
    
    # Start a worker task, giving it the channel to notify on
    @async worker(done)
    
    # Block until we receive a notification from the worker on the channel
    take!(done)
end

main()

This is the function we’ll run in a task. The done channel will be used to notify another task that this function’s work is done.

The main function starts a worker task, giving it the channel to notify on. It then blocks until it receives a notification from the worker on the channel.

To run the program, save it as channel_synchronization.jl and use:

$ julia channel_synchronization.jl
working...done

If you removed the take!(done) line from this program, the program would exit before the worker even started.

In Julia, we use Channels for communication between tasks, which are similar to goroutines in concept. The @async macro is used to create and schedule a new task, analogous to the go keyword. The put! and take! functions are used to send and receive values on a channel, respectively.