Go Goroutines & Channels Cheat Sheet

Covers launching goroutines with the go keyword, sending and receiving on channels, buffered versus unbuffered channels, and select statements.

2 PagesIntermediateApr 15, 2026

Basic Goroutines

Starting concurrent work with the go keyword.

func sayHello() {    fmt.Println("Hello from goroutine")}func main() {    go sayHello()                       // Starts a new goroutine (non-blocking)    time.Sleep(100 * time.Millisecond)  // Naive wait; use sync primitives in real code}

Channels

Typed pipes for communicating between goroutines.

ch := make(chan int)          // Unbuffered channelgo func() {    ch <- 42                  // Send value (blocks until received)}()value := <-ch                 // Receive value (blocks until sent)buffered := make(chan string, 3)  // Buffered channel, capacity 3buffered <- "a"buffered <- "b"close(buffered)               // Close when no more values will be sentfor v := range buffered {     // Range reads until the channel is closed    fmt.Println(v)}

sync.WaitGroup & select

Waiting for goroutines and multiplexing channel operations.

var wg sync.WaitGroupfor i := 0; i < 3; i++ {    wg.Add(1)    go func(id int) {        defer wg.Done()        fmt.Println("worker", id)    }(i)}wg.Wait()                     // Block until all goroutines call Done()select {case msg := <-ch1:    fmt.Println("from ch1:", msg)case msg := <-ch2:    fmt.Println("from ch2:", msg)case <-time.After(1 * time.Second):    fmt.Println("timeout")default:    fmt.Println("no message ready")}

Concepts

Vocabulary for Go's concurrency model.

go keyword- Launches a function call as a new lightweight goroutine, managed by the Go runtime
Unbuffered channel- Send blocks until a receiver is ready (a synchronous handoff)
Buffered channel- Send blocks only once the buffer is full
close(ch)- Signals no more values will be sent; receiving from a closed channel returns the zero value and false
sync.WaitGroup- Waits for a collection of goroutines to finish (Add/Done/Wait)
sync.Mutex- Protects shared state from concurrent access (Lock/Unlock)
select- Waits on multiple channel operations, choosing pseudo-randomly if more than one is ready

Pro Tip

"Don't communicate by sharing memory; share memory by communicating" — prefer channels to pass ownership of data between goroutines instead of protecting shared variables with mutexes wherever practical.

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