How does data transfer work between goroutines via an unbuffered channel at the stack level?

In Go, data transfer between goroutines via an unbuffered channel occurs synchronously and blocking at the stack level.

When one goroutine attempts to send a value to an unbuffered channel, it blocks until another goroutine reads that value from the channel. Similarly, if a goroutine tries to receive a value from the channel but there is no data in the channel, it blocks until a sender appears.

At the stack level, this is implemented as follows:

• The sending goroutine places the value into the channel structure and blocks, saving its state on the stack.
• The Go scheduler switches to another goroutine that reads from the channel.
• After the value is read, the receiving goroutine unblocks the sender, and both continue execution.

Thus, the channel acts as a synchronization point between goroutines, ensuring data transfer and coordination without the need for additional synchronization primitives.

This prevents data races and guarantees that data is transmitted only when both parties are ready.