Use of GOMAXPROCS settings in Go language

In Go,GOMAXPROCSis a very important setting, which determines the number of goroutines that can run simultaneously in the program. By default,GOMAXPROCSThe value of  is the same as the number of CPU cores of the machine, which can make full use of the concurrent processing capabilities of multi-core CPUs. However, in some environments, such as containerized environments (such as Docker),GOMAXPROCSThe default value of   may be the same as the number of CPU cores on the host, which may not match what we expect. This article will introduce in detailGOMAXPROCSSetting methods and precautions.

GOMAXPROCS default behavior

When running Go programs in a physical or virtual machine,GOMAXPROCSThe default is the same as the CPU core number. This means that your program can run on all cores in parallel, improving the concurrency performance of your program. For example, if your machine has 8 CPU cores, then the defaultGOMAXPROCSThe value is 8.

Modify the value of GOMAXPROCS

If you need to adjust the number of concurrent goroutines, you can use()Functions are set. This function accepts an integer parameter to setGOMAXPROCSvalue. If the parameter is 0, the function will return the currentGOMAXPROCSvalue without any modification.

Sample code

package main

import (
    "fmt"
    "runtime"
)

func main() {
    // Print the current CPU core number and GOMAXPROCS default value    ("CPU core number:", ())
    ("GOMAXPROCS default value:", (0))

    // Modify the value of GOMAXPROCS to twice the number of CPU cores    (() * 2)
    ("Modified GOMAXPROCS default value:", (0))
}

Output result

Number of CPU cores: 8
GOMAXPROCS default value: 8
Modified GOMAXPROCS default value: 16

Notes in container environment

In a container environment,GOMAXPROCSThe default value of   may be affected by the host configuration. For example, in a Docker container, the defaultGOMAXPROCSThe value may be the number of CPU cores of the host, which may cause poor concurrency performance of Go programs in the container. To solve this problem, you can use environment variables when starting the containerGOMAXPROCSto set its value, or set it dynamically in the program.

Set environment variables

In Dockerfile, you can set environment variables like this:

ENV GOMAXPROCS 4

Or specify when running the container:

docker run -e GOMAXPROCS=4 your_image

in conclusion

GOMAXPROCSIt is a key setting for controlling concurrency in the Go language. Understanding its default behavior and how to modify it can help you better optimize the performance of your Go program. Especially in containerized environments, set up reasonablyGOMAXPROCSIt is crucial to achieve efficient concurrent processing. Through the introduction of this article, I hope you can get it rightGOMAXPROCSHave a deeper understanding and be able to apply it correctly in your project.

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