Do Goroutine Return Values Disappear?

Fate of Return Values from Goroutines

In goroutines, do returned values vanish into the void? While performing operations within goroutines, it's crucial to understand what happens to the values they produce.

Where Returned Values Reside

The assembly output for the getNumber() function reveals an intriguing insight: even though the function returns an integer, it's stored on the goroutine's stack. This is because each goroutine operates within its own dedicated stack space.

Inaccessible Returns

However, despite storing the returned value, there's no way to access it outside the goroutine. As soon as the goroutine completes execution, its stack is destroyed, erasing the return value along with it. Thus, attempting to retrieve this value from the main routine is futile.

Avoidance of Return Values in Goroutines

Given the inaccessibility of return values, it's generally recommended to avoid using them in goroutines. Instead, consider alternative mechanisms for communication and data sharing between goroutines, such as channels or shared memory.

Example: Using Channels for Communication

In the provided example, the printNumber() function should send its returned value to the main routine via a channel:

func printNumber(i int) {
    ch := make(chan int)
    go func() {
        ch <- i
    }()
    // Perform other tasks while the goroutine sends the value
    // ...

    num := <-ch
    // Use the returned value from the goroutine
}

In this manner, the main routine can receive and process the return value from the goroutine asynchronously, ensuring communication and data sharing without the need for direct return value retrieval.

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