How to control the scheduler through GOMAXPROCS?

In Go, the environment variable or the runtime.GOMAXPROCS function sets the maximum number of operating system threads (OS threads) that can execute Go routines (goroutines) simultaneously. This affects the Go scheduler, which distributes goroutines across threads.

If GOMAXPROCS is set to 1, the scheduler will use only one thread, limiting parallelism and causing goroutines to execute sequentially, although they will still switch.

Example of setting in code:

import "runtime"

func main() {
    runtime.GOMAXPROCS(4) // allow the scheduler to use up to 4 threads
    // rest of the code
}

Thus, GOMAXPROCS can be used to control the level of parallelism and influence program performance, especially on multi-processor systems. It is important to choose the value depending on the task and available resources.