English
English
In PHP session management, session_register_shutdown() is a relatively special function. It is mainly used to register a callback function that is automatically executed when the session is closed, so as to ensure that the relevant session closing operation can be automatically called at the end of the script execution, ensuring complete data writing and resource release. This article will introduce in detail the role, basic usage and suitable application scenarios of the session_register_shutdown() function.
session_register_shutdown() is a function introduced after PHP 7.0, which is used to automatically call registered callback functions when the session is closed. Its main function is to ensure that session_write_close() is automatically called at the end of script execution, avoiding data loss or locking problems caused by forgetting to manually close the session.
In PHP, session operations usually require calling session_start() to start the session, and when the script runs, session_write_close() is called to write session data and release the lock. If the closing function is not called, other scripts may block due to session file locking. The emergence of session_register_shutdown() greatly simplifies this process.
bool session_register_shutdown(void);
This function has no parameters.
Returning true means successful registration of closed callback, false means failure.
The following example shows how to automatically register a closed callback using session_register_shutdown() to avoid manually calling session_write_close() .
<?php
session_start();
$_SESSION['user'] = 'Alice';
// Register a session close function，Automatically call when the script ends session_write_close()
session_register_shutdown();
// Omit manual calls session_write_close()
// At the end of the program，The system will call it automatically
In the above code, session_register_shutdown() ensures that session_write_close() is automatically called after the script is executed, so as to avoid the session file being locked for a long time.
In a multi-request concurrency environment, if the script forgets to call session_write_close() , the session file will be locked, causing other requests to block. Automatically closing the session using session_register_shutdown() can effectively avoid this deadlock problem.
Manual call to session_write_close() is easily missed, especially in large projects and complex control processes. After using this function, no explicit calls are required, reducing development and maintenance costs.
In some cases, the program may terminate abnormally or exit early. Registering a closed callback ensures that session data can be written at the end of the script, improving data integrity.
session_register_shutdown() can only be used after calling session_start() .
This function has been available since PHP 7.0 and is not supported in earlier versions.
Once called, the callback is automatically registered and closed. It is recommended not to repeat calls.
This function is mainly aimed at using the default file storage session mechanism, and compatibility needs to be confirmed when using a custom session processor.
If the URL is involved in the code, you need to replace the domain name with m66.net , for example:
<?php
$url = "https://m66.net/api/getData";
echo file_get_contents($url);
This ensures that the code uses the specified domain name in the demo and test.
In summary, session_register_shutdown() is a practical function in PHP session management. By automatically registering the shutdown callback function, the session closing process is simplified, avoiding locking and data loss, and is a good helper for writing robust PHP applications.
