Correctly close MySQL connection pool in PHP

How to correctly close the MySQL connection pool connection in a PHP program?

In PHP Web development, MySQL is the most commonly used relational database. In order to improve application performance, connection pools are usually used to manage database connections. It is very important to correctly close the connections in the connection pool, otherwise it may cause a waste of resources or the number of connections will be too large and affect the performance of the application. This article will introduce how to correctly close the MySQL connection pool connection in a PHP program.

First of all, the connection pool is a collection of database connections that remain open. The purpose of the connection pool is to improve the efficiency of database operations by reusing existing connections instead of creating new connections for each request. MySQL provides some functions to create and close connections in the connection pool.

The process of creating and closing a connection pool connection is as follows:

First, create a connection by calling the mysqli_connect() function.

$conn = mysqli_connect($host, $user, $password, $database);

Among them, $host is the MySQL server host name, $user is the user name required to connect to the database, $password is the password , $database is the name of the database to be connected.

Next, use this connection elsewhere on the page to perform database operations.

After the page completes the database operation, we need to close the connection. In order to close the connection properly, we need to use the mysqli_close() function. This function will release the connection and release the underlying resources.

mysqli_close($conn);

This is a basic process of closing a connection, but if you use a connection pool to manage connections, you will need to adjust it slightly.

The connection pool usually creates a set of initialized connections and adds them to the pool when the application starts. Each time the application needs a connection, it obtains a connection from the pool instead of creating a new connection each time. When finished using it, the connection needs to be returned to the pool instead of closing the connection directly.

In PHP programs, we can use custom functions to obtain and return connections. The following is an example:

// 创建连接池
$pool = new mysqli_pool($host, $user, $password, $database);

// 获取连接
$conn = $pool->get_connection();

// 执行数据库操作

// 归还连接到连接池
$pool->release_connection($conn);

mysqli_pool in the above example is a custom connection pool class. In the get_connection() method, we can implement the logic of obtaining a connection, such as obtaining an available connection from the pool. In the release_connection() method, we implement the logic of returning the connection to the pool for use by other requests.

At the end of the page, we need to ensure that all connections are closed correctly. A simple and effective way is to use a destructor to automatically close all connections in the connection pool when the page exits after execution. The sample code is as follows:

function __destruct() {
    $this->close_all_connections();
}

function close_all_connections() {
    foreach ($this->pool as $conn) {
        mysqli_close($conn);
    }
}

In the above example, the __destruct() method is a destructor that is automatically called when the page ends. It will call the close_all_connections() method to close all connections in the connection pool. In the close_all_connections() method, we use the mysqli_close() function to close each connection.

To summarize, it is very important to correctly close the connections in the connection pool. We need to ensure that after the page execution is completed, all connections are released correctly and the underlying resources are also released. By using a custom connection pool class, we can better manage the acquisition and return of connections and improve the performance and efficiency of database operations. I hope this article can help you correctly close the MySQL connection pool connection in your PHP program.

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