How to deal with MySQL connection error 1021?

How to deal with MySQL connection error 1021?

MySQL connection error 1021 means that the MySQL server cannot handle more connection requests due to exceeding a certain number of connection requests. When this error occurs, timely measures need to be taken to solve the problem to ensure the normal operation of the database. This article will introduce some common solutions.

1. Increase the maximum number of connections
Connection error 1021 is usually caused by the maximum number of connections of the MySQL server being set too low. You can increase the maximum number of connections by following the following steps:

1. Open the MySQL configuration file my.cnf
2. Find the [mysqld] section in the file
3. Add a line of max_connections = 1000 (the number can be adjusted according to specific needs)
4. Save the file and restart the MySQL service

2. Optimize existing connections
If the connection still occurs after increasing the maximum number of connections Error 1021 indicates that it is not just a problem with the number of connections, but there may be other problems. The following are some common optimization methods:

1. Check and optimize the query statement: Make sure the query statement uses appropriate indexes to avoid full table scans.
2. Close unnecessary connections: Check the application's connection pool settings to ensure that connections are released promptly after use.
3. Reduce concurrent requests: For larger query requests, you can reduce the number of connections initiated simultaneously by batch processing or using asynchronous operations.
4. Optimize server configuration: Increase the server’s hardware resources (such as CPU, memory), and adjust MySQL parameter configuration according to the actual situation.

3. Use connection pool
Connection pool can effectively manage database connections and reduce the cost of connection creation and release by reusing connections. Using the connection pool can achieve the following effects:

1. Control the number of concurrent connections: The connection pool can set the maximum number of connections and the minimum number of connections to limit the number of connections.
2. Automatically recycle idle connections: For connections that have not been used for a long time, the connection pool will automatically recycle them and release resources.
3. Reducing database pressure: The connection pool can reduce the number of connections and releases by reusing connections, thereby reducing the pressure on the database server.

4. Increase hardware resources
If the above method still cannot solve the connection error 1021, consider increasing the server's hardware resources, including CPU, memory, hard disk, etc. Adding hardware resources can increase the database's processing power to accommodate more connections.

Summary:
MySQL connection error 1021 is a common connection problem, but it can be solved by increasing the maximum number of connections, optimizing existing connections, using connection pools, and increasing hardware resources. When solving problems, you need to choose the appropriate method according to the specific situation, and make appropriate adjustments and tests. As long as it is properly configured and optimized, connection error 1021 can be successfully resolved and the normal operation of the database can be ensured.

The above is the detailed content of How to deal with MySQL connection error 1021?. For more information, please follow other related articles on the PHP Chinese website!