Why Does My Go Program Hang Even After Setting `runtime.GOMAXPROCS(2)`?

Understanding Persistence in Concurrency: Resolving "GOMAXPROCS Already Set to 2, But Program Still Hangs"

A developer encountered a perplexing issue where a program continued to hang despite setting runtime.GOMAXPROCS(2) to enable concurrency. This issue stems from a common misunderstanding in concurrency: the impact of infinite loops on program execution.

In the given code, two goroutines are spawned: one executing an infinite loop in the forever() function and another printing numbers incrementally in the show() function. Setting GOMAXPROCS(2) specifies that the program should utilize two CPU cores for running goroutines.

However, the problem arises within the forever() function. Infinite loops, like the one in this function, consume an entire operating system thread. This means that the thread is constantly running without yielding, preventing other goroutines from executing. Consequently, the program appears to hang despite utilizing multiple CPU cores.

To resolve this issue, it is crucial to remove unnecessary infinite loops. In this case, the forever() function serves no purpose and can be replaced with a simple for {} loop to allow other goroutines to schedule. Alternatively, a scheduling point can be inserted within the loop using runtime.Gosched(), which allows the runtime scheduler to preempt the goroutine and give other goroutines a chance to run.

By eliminating infinite loops or introducing scheduling points, the program will behave as expected and leverage concurrency effectively. This understanding highlights the importance of carefully designing goroutine interactions to avoid performance issues and maintain program responsiveness.

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