A brief discussion on the differences between several versions of PHP

The editor of this article will take you to understand the differences between various versions of PHP. Friends who are interested can learn about it. I hope it will be helpful to you.

The PHP version, since entering version 5, the speed of releasing new versions has obviously improved a lot. Starting from PHP5.2, 5.3, 5.4, 5.5, it is almost 6.0.

Note: ecshop users please consciously use php5.2.17 version. hehe.

When downloading php from the php official website, we will find the difference between vc6 and vc9. What does this mean?

VC6 is the legacy Visual Studio 6 compiler. If you use this version of the compiler to compile PHP code and use apache as the application server, choose vc6.
VC9 is the Visual Studio 2008 compiler, which is compiled using Microsoft's VS editor. If you use IIS as the application server, choose vc9.

So, we noticed that in the decompressed file of php-5.2.17-nts-Win32-VC6-x86.zip php, there is a difference between nts and no nts. What does this mean?

This starts with the 5.2 series version of php. Starting from version 5.2.1, there is a difference between ts and nts, Thread Safe (thread safe) and None Thread Safe (NTS, non-thread safe)

The Windows version of PHP has Thread starting from version 5.2.1 What is the difference between Safe (thread safety) and None Thread Safe (NTS, non-thread safety)? Which one should be used? Here is a brief introduction.

Starting from the first Windows version of PHP 3.0.17 released on October 20, 2000, all versions are thread-safe. This is because the Linux/Unix system uses a multi-process working method, and Windows The system uses a multi-threaded working method. If you run PHP in CGI mode under IIS, it will be very slow, because CGI mode is based on multi-process, not multi-thread. We will configure PHP to run in ISAPI mode on Windows, because ISAPI is a multi-threaded method, which is much faster.

But there is a problem. Many commonly used PHP extensions are developed based on the multi-process idea of ​​Linux/Unix. These extensions will go wrong when running in ISAPI mode, and may crash the IIS process. Therefore For IIS, CGI mode is the safest way to run PHP, but CGI mode requires reloading and unloading the entire PHP environment for each HTTP request, and its consumption is huge.
In order to take into account the efficiency and security of PHP under IIS, Microsoft provides the FastCGI solution. FastCGI allows PHP processes to be reused instead of reopening a process for each new request. At the same time, FastCGI can also allow several processes to execute at the same time. This not only solves the problem of excessive consumption of CGI process mode, but also takes advantage of the fact that CGI process mode does not have thread safety issues.
Therefore, if you use ISAPI to run PHP, you must use the Thread Safe (thread safe) version; and if you use FastCGI mode to run PHP, there is no need to use thread safety check, use None Thread Safe (NTS, non Thread-safe) version can better improve efficiency.

According to different webservers, that is, application servers, when processing application requests, some use multi-threading instead of multi-process. Since threads will involve shared registers and memory, so It is easy to make mistakes (consider the situation of C language pointers), then the system needs time and resources to process the data in the registers and ensure their consistency, which is to ensure thread safety.

So whether to use Thread Safe (thread safety) mainly depends on the PHP request processing method used by the web server. If it is multi-threaded processing such as the ISAPI method of IIS, then please choose thread safety. If it is FastCGI, then choose Not thread safe.

Final suggestion: Under IIS, if you use ISAPI to run PHP, use the Thread Safe (thread safe) version; if you use FastCGI to run PHP, use the None Thread Safe (NTS, non-thread safe) version.

Note: php5.2 does not have vc9, php5.3 and php5.4 do not have vc6. hehe. Starting from PHP 5.5, it no longer supports xp and win2003, and it also supports vc11, hahahaha.

Related tutorials: PHP video tutorial

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