PHP5+引进$GLOBALS延迟初始化的概念
今天整理代码想使用$GLOBALS['_SERVER']来替代$_SERVER来访问相关的环境变量,总是会报“_SERVER undefined”错误。如下用例:
用例1:
print_r($GLOBALS);
此时输出中并没有_SERVER相关信息:
Array
(
[GLOBALS] => Array
*RECURSION*
[_POST] => Array
(
)
[_GET] => Array
(
)
[_COOKIE] => Array
(
)
[_FILES] => Array
(
)
)
用例2:
print_r($GLOBALS);
print_r($_SERVER);
此时输出中含有_SERVER相关信息:
Array
(
[GLOBALS] => Array
*RECURSION*
[_POST] => Array
(
)
[_GET] => Array
(
)
[_COOKIE] => Array
(
)
[_FILES] => Array
(
)
[_SERVER] => Array
(
)
)
查了下PHP手册关于$GLOBALS描述,引用therandshow at gmail dot com的评论:
therandshow at gmail dot com
As of PHP 5.4 $GLOBALS is now initialized just-in-time. This means there now is an advantage to not use
the $GLOBALS variable as you can avoid the overhead of initializing it. How much of an advantage that is
I'm not sure, but I've never liked $GLOBALS much anyways.
追根数源,发现PHP5Changelog更新日志的描述:
Unordered List ItemImproved Zend Engine, performance tweaks and optimizations
Unordered List ItemChanged $GLOBALS into a JIT autoglobal, so it's initialized only if used. (this may affect opcode caches!)www.2cto.com
718 ; When enabled, the SERVER and ENV variables are created when they're first
719 ; used (Just In Time) instead of when the script starts. If these variables
720 ; are not used within a script, having this directive on will result in a
721 ; performance gain. The PHP directives register_globals, register_long_arrays,
722 ; and register_argc_argv must be disabled for this directive to have any affect.
723 ; http://php.net/auto-globals-jit
724 auto_globals_jit = On
终于弄明白了,PHP5+中在开启auto_globals_jit = On情况下,$_SERVER变量和$_ENV变量不会在脚本启动时就创建,而是会在第一次使用$SERVER和$ENV时才会创建。所以就会出现上述两个用例的情况。
备注:
实测结论:
auto_globals_jit setting is also affecting $_REQUEST superglobal in 5.3 It is not explicitly stated in documentation.
至少5.3.13版本中开启auto_globals_jit = On情况下,$_REQUEST也只会在第一次使用时才会创建。

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

CrystalDiskMark is a small HDD benchmark tool for hard drives that quickly measures sequential and random read/write speeds. Next, let the editor introduce CrystalDiskMark to you and how to use crystaldiskmark~ 1. Introduction to CrystalDiskMark CrystalDiskMark is a widely used disk performance testing tool used to evaluate the read and write speed and performance of mechanical hard drives and solid-state drives (SSD). Random I/O performance. It is a free Windows application and provides a user-friendly interface and various test modes to evaluate different aspects of hard drive performance and is widely used in hardware reviews

foobar2000 is a software that can listen to music resources at any time. It brings you all kinds of music with lossless sound quality. The enhanced version of the music player allows you to get a more comprehensive and comfortable music experience. Its design concept is to play the advanced audio on the computer The device is transplanted to mobile phones to provide a more convenient and efficient music playback experience. The interface design is simple, clear and easy to use. It adopts a minimalist design style without too many decorations and cumbersome operations to get started quickly. It also supports a variety of skins and Theme, personalize settings according to your own preferences, and create an exclusive music player that supports the playback of multiple audio formats. It also supports the audio gain function to adjust the volume according to your own hearing conditions to avoid hearing damage caused by excessive volume. Next, let me help you

NetEase Mailbox, as an email address widely used by Chinese netizens, has always won the trust of users with its stable and efficient services. NetEase Mailbox Master is an email software specially created for mobile phone users. It greatly simplifies the process of sending and receiving emails and makes our email processing more convenient. So how to use NetEase Mailbox Master, and what specific functions it has. Below, the editor of this site will give you a detailed introduction, hoping to help you! First, you can search and download the NetEase Mailbox Master app in the mobile app store. Search for "NetEase Mailbox Master" in App Store or Baidu Mobile Assistant, and then follow the prompts to install it. After the download and installation is completed, we open the NetEase email account and log in. The login interface is as shown below

Cloud storage has become an indispensable part of our daily life and work nowadays. As one of the leading cloud storage services in China, Baidu Netdisk has won the favor of a large number of users with its powerful storage functions, efficient transmission speed and convenient operation experience. And whether you want to back up important files, share information, watch videos online, or listen to music, Baidu Cloud Disk can meet your needs. However, many users may not understand the specific use method of Baidu Netdisk app, so this tutorial will introduce in detail how to use Baidu Netdisk app. Users who are still confused can follow this article to learn more. ! How to use Baidu Cloud Network Disk: 1. Installation First, when downloading and installing Baidu Cloud software, please select the custom installation option.

If you need to program any device remotely, this article will help you. We will share the top GE universal remote codes for programming any device. What is a GE remote control? GEUniversalRemote is a remote control that can be used to control multiple devices such as smart TVs, LG, Vizio, Sony, Blu-ray, DVD, DVR, Roku, AppleTV, streaming media players and more. GEUniversal remote controls come in various models with different features and functions. GEUniversalRemote can control up to four devices. Top Universal Remote Codes to Program on Any Device GE remotes come with a set of codes that allow them to work with different devices. you may

MetaMask (also called Little Fox Wallet in Chinese) is a free and well-received encryption wallet software. Currently, BTCC supports binding to the MetaMask wallet. After binding, you can use the MetaMask wallet to quickly log in, store value, buy coins, etc., and you can also get 20 USDT trial bonus for the first time binding. In the BTCCMetaMask wallet tutorial, we will introduce in detail how to register and use MetaMask, and how to bind and use the Little Fox wallet in BTCC. What is MetaMask wallet? With over 30 million users, MetaMask Little Fox Wallet is one of the most popular cryptocurrency wallets today. It is free to use and can be installed on the network as an extension

Apple rolled out the iOS 17.4 update on Tuesday, bringing a slew of new features and fixes to iPhones. The update includes new emojis, and EU users will also be able to download them from other app stores. In addition, the update also strengthens the control of iPhone security and introduces more "Stolen Device Protection" setting options to provide users with more choices and protection. "iOS17.3 introduces the "Stolen Device Protection" function for the first time, adding extra security to users' sensitive information. When the user is away from home and other familiar places, this function requires the user to enter biometric information for the first time, and after one hour You must enter information again to access and change certain data, such as changing your Apple ID password or turning off stolen device protection.

WindowsServerBackup is a function that comes with the WindowsServer operating system, designed to help users protect important data and system configurations, and provide complete backup and recovery solutions for small, medium and enterprise-level enterprises. Only users running Server2022 and higher can use this feature. In this article, we will explain how to install, uninstall or reset WindowsServerBackup. How to Reset Windows Server Backup If you are experiencing problems with your server backup, the backup is taking too long, or you are unable to access stored files, then you may consider resetting your Windows Server backup settings. To reset Windows
