Why Does My Go Program Freeze Despite Setting `runtime.GOMAXPROCS(2)`?

GOMAXPROCS Set to 2, But Program Remains Impaired

Despite setting runtime.GOMAXPROCS(2), a program encounters suspension issues while outputting numbers. While high CPU usage is observed, the cause for the malfunction remains elusive.

The provided code features two goroutines: forever(), a busy loop, and show(), which prints numbers in an endless loop. The main function sets GOMAXPROCS to utilize two CPU cores. However, the program becomes unresponsive.

The issue resides in the continuous operation of forever(). By constantly running, it consumes an entire OS thread and disrupts the runtime's goroutine scheduling. In Go 1.5 specifically, it obstructs the garbage collection's stop-the-world phase.

To resolve this, the busy loop in forever() can be replaced with a function that yields the CPU regularly. Alternatively, it could be removed altogether, as an endless loop is unnecessary.

For instance, modifying forever() as follows resolves the problem:

func forever() {
    for {
        runtime.Gosched()
    }
}

By introducing a scheduling point into the loop, the goroutine can relinquish control and allow other goroutines to execute. This ensures that all goroutines, including those responsible for core functionality, can run efficiently.

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