


In-depth analysis of the difference between PHP thread-safe and non-thread-safe versions_PHP Tutorial
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 Windows system uses a multi-process working method different from the Linux/Unix system. It adopts multi-threaded working method. If you run PHP in CGI mode under IIS, it will be very slow. This is because the CGI mode is based on multi-process, not multi-thread.
Generally, we will configure PHP to run in ISAPI mode. 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 thinking of Linux/Unix. When these extensions are run in ISAPI mode, they will go wrong and bring down IIS. Therefore, CGI mode is the safest way to run PHP under IIS, 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 has provided a 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.
There are 4 versions of Widows on PHP official http://php.net/: VC9 x86 Non Thread Safe, VC9 x86 Thread Safe, VC6 x86 Non Thread Safe, VC6 x86 Thread Safe; so what is the difference?
1. The supported servers are different
The VC9 version is for the IIS server and does not support APACHE, while the VC6 version provides support for both IIS and apache
What is VC6?
VC6 is the legacy Visual Studio 6 compiler, which is compiled using this compiler.
What is VC9?
VC9 is the Visual Studio 2008 compiler, which is compiled with Microsoft's VS editor.
So how do we choose which version of PHP to download?
If you are using Apache+PHP under windows, please choose the VC6 version;
If you are using IIS+PHP under windows, please choose the VC9 version;
2. Different running modes
PHP has 2 running modes: ISAPI and FastCGI.
The ISAPI execution method is used in the form of a DLL dynamic library, which can be executed after being requested by the user. It will not disappear immediately after processing a user request, so a thread safety check is required to improve the execution efficiency of the program. Therefore, if you are using ISAPI to execute PHP, it is recommended to choose the Thread Safe version;
The FastCGI execution method uses a single thread to perform operations, so there is no need to perform thread safety checks. Removing the protection of thread safety checks can improve execution efficiency. Therefore, if FastCGI is used to execute PHP, it is recommended to choose Non Thread Safe version.
For the apache server, the isapi method is generally selected, while for the nginx server, the FastCGI method is selected.

Calculating the total number of elements in a PHP multidimensional array can be done using recursive or iterative methods. 1. The recursive method counts by traversing the array and recursively processing nested arrays. 2. The iterative method uses the stack to simulate recursion to avoid depth problems. 3. The array_walk_recursive function can also be implemented, but it requires manual counting.

In PHP, the characteristic of a do-while loop is to ensure that the loop body is executed at least once, and then decide whether to continue the loop based on the conditions. 1) It executes the loop body before conditional checking, suitable for scenarios where operations need to be performed at least once, such as user input verification and menu systems. 2) However, the syntax of the do-while loop can cause confusion among newbies and may add unnecessary performance overhead.

Efficient hashing strings in PHP can use the following methods: 1. Use the md5 function for fast hashing, but is not suitable for password storage. 2. Use the sha256 function to improve security. 3. Use the password_hash function to process passwords to provide the highest security and convenience.

Implementing an array sliding window in PHP can be done by functions slideWindow and slideWindowAverage. 1. Use the slideWindow function to split an array into a fixed-size subarray. 2. Use the slideWindowAverage function to calculate the average value in each window. 3. For real-time data streams, asynchronous processing and outlier detection can be used using ReactPHP.

The __clone method in PHP is used to perform custom operations when object cloning. When cloning an object using the clone keyword, if the object has a __clone method, the method will be automatically called, allowing customized processing during the cloning process, such as resetting the reference type attribute to ensure the independence of the cloned object.

In PHP, goto statements are used to unconditionally jump to specific tags in the program. 1) It can simplify the processing of complex nested loops or conditional statements, but 2) Using goto may make the code difficult to understand and maintain, and 3) It is recommended to give priority to the use of structured control statements. Overall, goto should be used with caution and best practices are followed to ensure the readability and maintainability of the code.

In PHP, data statistics can be achieved by using built-in functions, custom functions, and third-party libraries. 1) Use built-in functions such as array_sum() and count() to perform basic statistics. 2) Write custom functions to calculate complex statistics such as medians. 3) Use the PHP-ML library to perform advanced statistical analysis. Through these methods, data statistics can be performed efficiently.

Yes, anonymous functions in PHP refer to functions without names. They can be passed as parameters to other functions and as return values of functions, making the code more flexible and efficient. When using anonymous functions, you need to pay attention to scope and performance issues.


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