What is GOMAXPROCS, why is it needed, and how does it work?

GOMAXPROCS is an environment variable or setting in Go that determines the maximum number of operating system threads (OS threads) that the Go scheduler can use simultaneously to run goroutines.

By default, the GOMAXPROCS value is equal to the number of logical processors on the machine, which allows efficient utilization of multi-processor systems.

How it works:

• Go launches multiple goroutines — lightweight threads within the application.
• The Go scheduler distributes these goroutines across available OS threads.
• GOMAXPROCS limits the number of such threads to prevent excessive competition for CPU resources.

Example of setting GOMAXPROCS in code:

import (
    "runtime"
)

func main() {
    runtime.GOMAXPROCS(4) // limit to 4 threads
    // rest of the code
}

Thus, GOMAXPROCS helps manage parallelism and performance of a Go application.