Can Continuously Running Goroutines Starve Other Goroutines in Go?

Goroutine Cooperative Scheduling and Potential Execution Starvation

Goroutines are cooperatively scheduled, meaning they voluntarily yield execution to other goroutines. While this approach generally ensures fairness, it raises the question of whether goroutines that refrain from yielding can potentially starve other goroutines.

According to the referenced blog post (http://blog.nindalf.com/how-goroutines-work/), goroutines that loop continuously without yielding can indeed starve other goroutines on the same thread. Goroutines on a specific thread are multiplexed, meaning they do not block the thread even when encountering blocking operations like network input, sleeping, or channel operations.

As an example, the "sum" function in the given code repeatedly loops a random number of times, adding numbers to a sum and printing the final result. If multiple such goroutines are spawned using the "go" keyword (as shown in the example), whether they execute one by one depends on the following factors:

• Number of available threads (GOMAXPROCS): If GOMAXPROCS is set to 1, all goroutines will execute sequentially on a single thread, resulting in starvation.
• Yielding points: Within the sum function, there are no function calls or synchronization primitives that would allow goroutines to yield. Consequently, the goroutine will hold the thread until it completes.
• Recent runtime changes: The quoted blog post is slightly outdated. Newer versions of the Go runtime may schedule goroutine switching even for functions with no explicit yield points, such as "fmt.Println". This is done to prevent potential starvation.

Therefore, in the absence of explicit yielding or function calls that trigger scheduling, goroutines that execute infinite loops can potentially starve other goroutines on the same thread. However, it's important to note that the Go runtime actively attempts to balance goroutine execution and prevent starvation.

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