In Python, you can use third-party libraries to create database connection pools. The following uses the pymysql library as an example to introduce how to create a MySQL database connection pool. First, you need to install the pymysql library:
Next, you can use the Pool class in the pymysql.pool module to create a database connection pool. The constructor of the Pool class needs to pass in the following parameters:
The following is a sample code showing how to use the Pool class to create a MySQL database connection pool:
In this example, a MySQLPool class is first defined, which contains methods for creating and managing MySQL database connection pools. In the __init__ method, create a Pool object by passing in the configuration parameters. The creator parameter specifies that you want to use Python to create a database connection pool using pymysql. You can use a third-party library to implement this function. Common Python database connection pools include the following:
1. SQLAlchemy: It is one of the most commonly used ORM frameworks in Python and also includes the connection pool function. You can use SQLAlchemy to create a connection pool and use it to connect to MySQL, PostgreSQL, Oracle and other databases. The following is sample code for using SQLAlchemy to create a MySQL database connection pool:
Among them, pool_size represents the number of connections in the connection pool, and max_overflow represents the maximum number of connections allowed in the connection pool. If the connection pool is full, new connections will be created until the number of connections reaches pool_size+max_overflow. The poolclass parameter indicates the type of connection pool selected, and the QueuePool type is used here.
2. DBUtils: It is a commonly used Python database connection pool library. It supports a variety of databases and provides connection pooling and connection pool manager functions. The sample code for using DBUtils to create a connection pool is as follows: 
where maxconnections represents the number of connections in the connection pool, maxcached represents the maximum number of cached connections in the cache pool, and maxusage represents the maximum number of uses of each connection in the connection pool. If the number of connections reaches maxconnections, new requests will be blocked until an idle connection is available.
The above are two common Python database connection pool implementation methods. You can choose one or other libraries according to your own needs.