search
HomeBackend DevelopmentPHP TutorialUnderstand the configuration of max_children in php-fpm

Understand the configuration of max_children in php-fpm

Now nginx fpm has basically become the mainstream configuration, among which we are more concerned about the configuration of pm.max_chindren

First, we pay attention to a setting: pm = static/dynamic.

Related learning recommendations: PHP programming from entry to proficiency

This option is to identify the generation mode of the fpm child process :

static : means directly forking out pm.max_chindren worker processes when fpm is running

dynamic: means that start_servers processes will be forked during runtime, and will be dynamically adjusted according to the load, up to no more than max_children processes.

It is generally recommended to use static. The advantage is that it does not need to dynamically determine the load situation and improves performance. The disadvantage is that it takes up more system memory resources.

The above tells us the number of worker processes represented by max_chindren. It is generally believed that the more concurrency this configuration can handle at the same time, this is a relatively big misunderstanding:

  • #1) In fact, there are more processes, which increases the cost of process switching, which is more core. Yes, the number of fpm processes that can be executed concurrently will not exceed the number of CPUs. It is a wrong understanding to increase QPS by opening more workers. It does not mean that if you open more processes, you will have more CPUs for processing.
  • 2) There are fewer worker processes. If the server is busy, it will cause nginx to hit the data to fpm. It will be found that all workers are working and there are no idle workers to accept requests, thus Resulting in 502.
  • 3) In actual business, since we have a lot of I/O operations, such as reading the database, or internal RPC calls, while waiting for I/O, the process will be sleep by the system, and It does not occupy the CPU. If fewer workers are configured, the CPU will not be utilized.

So how should the number of workers be configured?

Theoretically, the number of woker processes = the number of CPUs is the most reasonable, but due to point 2, each worker may not have finished processing the request, so 502 will occur frequently. But opening more processes just means to avoid 502 and temporarily hang the request, but this is only a way to alleviate it. In fact, this will not only increase the concurrency of the system, but also increase the load of the system. Therefore, based on 2 and 3, set a A reasonable number of workers is more important.

The only martial arts in the world that can only be fast is to improve the efficiency of the program as much as possible and compress the time of a single request to the minimum. In this way, the processing time of a single worker is shortened, which can be processed in unit time. Naturally, there were more requests.

Then the number of max_children can be estimated by the number of requests processed by each worker in unit time. If the processing time of the largest request (cpu time in xhprof) is within 100ms, and 100 requests come in at the same time within 100ms, then in theory, 100 worker processes need to be configured to hang the requests first.

However, the maximum request time may be affected by many external circumstances and is difficult to estimate, especially network I/O is also included. We can borrow third-party profile tools, such as xhprof , this type of tool can count CPU time consumption. Calculating the real number of workers through this time is much more reasonable than calculating the total time. In fact, there is a shortcut here to configure your max_children number, which is to set max_childnren in the early stage. into a relatively large value. After running stably for a period of time, observe the max active processes in the status of fpm, and then configure max_children to be larger than it. It will be ok.

The above is the detailed content of Understand the configuration of max_children in php-fpm. For more information, please follow other related articles on the PHP Chinese website!

Statement
This article is reproduced at:jb51. If there is any infringement, please contact admin@php.cn delete
The Continued Use of PHP: Reasons for Its EnduranceThe Continued Use of PHP: Reasons for Its EnduranceApr 19, 2025 am 12:23 AM

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python: Exploring Their Similarities and DifferencesPHP and Python: Exploring Their Similarities and DifferencesApr 19, 2025 am 12:21 AM

PHP and Python are both high-level programming languages ​​that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP and Python: Different Paradigms ExplainedPHP and Python: Different Paradigms ExplainedApr 18, 2025 am 12:26 AM

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP and Python: A Deep Dive into Their HistoryPHP and Python: A Deep Dive into Their HistoryApr 18, 2025 am 12:25 AM

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

Choosing Between PHP and Python: A GuideChoosing Between PHP and Python: A GuideApr 18, 2025 am 12:24 AM

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP and Frameworks: Modernizing the LanguagePHP and Frameworks: Modernizing the LanguageApr 18, 2025 am 12:14 AM

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHP's Impact: Web Development and BeyondPHP's Impact: Web Development and BeyondApr 18, 2025 am 12:10 AM

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

How does PHP type hinting work, including scalar types, return types, union types, and nullable types?How does PHP type hinting work, including scalar types, return types, union types, and nullable types?Apr 17, 2025 am 12:25 AM

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values ​​and handle functions that may return null values.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software