How to deal with MySQL connection error 1212?

How to deal with MySQL connection error 1212?

In daily database use, we often encounter some error messages, one of which is MySQL connection error 1212. When this error occurs, it means that the MySQL server cannot run more threads, causing new connection requests to be rejected. This error often occurs when the number of concurrent connections is too high or the server is improperly configured. So how do we deal with this error? Here are some solutions and preventive measures.

First, we need to confirm the configuration of the database server. When connection error 1212 occurs, it is usually caused by the server's maximum number of connections being configured too low. We can view the current maximum number of connections configuration by executing the following command on the MySQL console:

SHOW VARIABLES LIKE 'max_connections';

If it is found that the current maximum number of connections is set relatively low, We can increase the maximum number of connections by modifying the configuration file. Find and edit the MySQL configuration file my.cnf (usually located in the /etc/mysql or /etc/mysql/mysql.conf.d directory), find or add the following line in the [mysqld] section:

max_connections = 1000

Replace 1000 with the maximum number of connections you want. Note that increasing the maximum number of connections will also increase the load on the server, so consider carefully when choosing an appropriate value.

After modifying the configuration file, save and restart the MySQL service. Use the following command to confirm whether the maximum number of connections takes effect:

SHOW VARIABLES LIKE 'max_connections';

In addition, We can also determine whether we need to increase the maximum number of connections by checking the current number of connections on the MySQL server. You can use the following command to view the current number of connections on the MySQL console:

SHOW STATUS LIKE 'Threads_connected';

If you find that the current number of connections is close to the maximum number of connections, it means that the server is loaded The bottleneck has been reached, and we need to increase the maximum number of connections or optimize the database structure to share the load.

In addition, we can also consider optimizing database query statements to reduce database load. By rationally using indexes, optimizing query statements, and avoiding unnecessary multi-table associations, the performance and response speed of the database can be improved, and the occurrence of connection error 1212 can be reduced.

Finally, we need to pay attention to the configuration of the number of concurrent connections in the database to be compatible with the hardware resources of the server. If the server's hardware resources are limited and cannot support a large number of concurrent connections, then we can choose to perform connection pool management in the application to limit the usage time of each connection and avoid excessive connection idle time. At the same time, rational use of database connection resources and timely release of connections can also effectively reduce the occurrence of connection error 1212.

To summarize, methods to deal with MySQL connection error 1212 include: checking and adjusting the configuration of the maximum number of connections, optimizing database query statements, rational use of connection pool management, etc. Through the above measures, we can solve the problem of connection error 1212 and improve the performance and stability of the database. At the same time, we also need to pay attention to the importance of hardware resource configuration of the database and reasonable use of connection resources to ensure the smooth operation of the database.

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