How to Verify the Number of Processors Used by a Go Program?

Golang: Verifying Number of Processors Allocated to a Program

Determining the number of processors allocated to a Go program is crucial for optimizing performance. This article addresses the question of how to verify the number of processors running a program when the runtime.GOMAXPROCS variable is modified.

To verify the allocated processors, Go provides the runtime.NumCPU() function. This function retrieves the maximum number of available logical CPUs on the host system. Here's how to use it:

fmt.Println("Number of allocated processors:", runtime.NumCPU())

The maximum number of logical CPUs a program can utilize is the minimum of runtime.GOMAXPROCS(0) and runtime.NumCPU(). This value can be obtained using the MaxParallelism function:

func MaxParallelism() int {
    maxProcs := runtime.GOMAXPROCS(0)
    numCPU := runtime.NumCPU()
    if maxProcs < numCPU {
        return maxProcs
    }
    return numCPU
}

By comparing the output of runtime.NumCPU() with runtime.MaxParallelism(), you can determine the actual number of processors allocated to the program.

Even when GOMAXPROCS is set to a value greater than 1, the 'top' command may show the 'a.out' process utilizing less than 100% of resources. This is because the Go runtime scheduler may not fully utilize all available processors at all times. It depends on factors such as program concurrency, task scheduling, and system load.

The above is the detailed content of How to Verify the Number of Processors Used by a Go Program?. For more information, please follow other related articles on the PHP Chinese website!