![]() ![]() Restart the MySQL service to apply the change. Then, append the following line inside MySQL configuration file, under the directive: max_connections = 265 It doesn’t make sense to configure a higher value than that. If you are running in the older version, take this variable into account.įrom this example, we can have up to 265 MySQL connections simultaneously according to the available RAM the host has. **Variable innodb_additional_mem_pool_size is removed in MySQL 5.7.4+. Then, specify the available memory, 1928 MB in the following statement: mysql> SELECT ROUND((1928 - + + + + / 1024 / 1024))) / + + + + + / 1024 / 1024)) AS 'Possible Max Connections' Just for the info, the ‘available’ column gives an estimate of how much memory is available for starting new applications, without swapping (only available in kernel 3.14+). Total used free shared buff/cache available Then, retrieve the available RAM (in MB) of the host (look under ‘available’ column): $ free -m | 232172 | root | localhost | NULL | Query | 0 | NULL | show processlist | 0.000 |įrom the above output, we can tell that only one user is connected to the MySQL server which is root. | Id | User | Host | db | Command | Time | State | Info | Progress | You can use ‘mysqladmin’ or ‘SHOW PROCESSLIST’ for this purpose: $ mysqladmin -uroot -p processlist Ensure you only have the minimum number of processes running at that particular moment. To start the process, stop all connections from clients and restart the MySQL server. If you are running in the older version, take this variable into account.īy using the above formulas, we can calculate a suitable max_connections value for this particular MySQL server. ![]() **Variable innodb_additional_mem_pool_size is removed in MySQL 5.7.4+. To determine a good number for max_connections, the basic formulas are: The number of connections permitted to a MySQL server is controlled by the max_connections system variable. Webinar Replay & Slides: How to build scalable database infrastructures with MariaDB & HAProxy Note that timeout is another important parameter that we should know, but we are going to cover that in a separate post. In this blog post, we will dive into MySQL’s max_connections and HAProxy maxconn options respectively. If you have such setup, it is important to understand these components as they can impact the overall performance of your database service. Ideally, we would need to configure these two components together so as to avoid unexpected behaviours, and narrow down the troubleshooting surface when debugging issues. MySQL, on the other hand, has its own way of managing client connections. Theoretically, a load balancer which sits in front of MySQL servers (for example an HAProxy in front of a Galera Cluster) should just act like a connection manager and distribute the connections to the backend servers according to some balancing algorithm.
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