Channel Ordering in Go: Is Send Order Preserved When Blocked?

Channel Ordering When Blocked: A Deeper Insight

In the realm of concurrent programming with channels in Go, it's crucial to understand how channels behave when blocked due to capacity limitations. The question at hand revolves around whether the order of sending is preserved when multiple goroutines are blocked on writing.

The Go specification states that when a channel has a capacity greater than zero, it operates asynchronously. Communication operations succeed without blocking if the buffer is not full for sends or not empty for receives. Additionally, elements are received in the order they are sent.

However, this statement applies to situations where the buffer is not full, implying that communication operations succeed immediately without blocking. It provides no explicit guarantees about the order of sends after a channel becomes unblocked.

In reality, when multiple goroutines are blocked on writing to a channel, there is no guarantee that the sender that was initiated first will ultimately succeed first. The scheduler in Go may yield to another goroutine, even though the first goroutine has already started executing.

Therefore, it's important to note that the order of sending when multiple goroutines are blocked on writing to a channel is not guaranteed. Messages may arrive in a different order than they were sent, even if the channel has a capacity greater than zero.

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