![]() what tool) are you using to observe that connection count is increasing?Īlso another question for you. What connection pool and what version are you using?Īlso another question for you. Bug in the DB Connection Pool: May be there is a bug in the DB connection pool which is causing the connection to leak. You might want to take thread dump from the application and see whether threads are holding on to the connections.Ĥ. In that scenario also connection count will continue to grow. In such circumstances threads will be still continuing to hold on to the connection. Threads are holding on to connection: Sometimes certain SQL call might take long time to complete. ![]() It could be quite possibly happening in your application.ģ. ![]() Sometimes I have seen when there is an exception in the code, developers misses to close connection. Application is not closing connection in certain scenarios: May be for certain type of DB calls, your application isn't closing the connections. Rule of thumb: Max number of connections 4 times available CPU. It will show how many connections are established to your MySQL DB and what TCP/IP state they are in.Ģ. MySQL is very good at handling many clients connecting and disconnecting to the database at a high frequency, up to 80 thousand connect and disconnects per second MySQL scales well on multi-core CPUs and can deliver up to 2 million primary key look-ups per second on 48 CPU cores. You can confirm this by issuing 'netstat' command on the machine where tomcat is running. Probably they are going in to CLOSE_WAIT, FIN_WAIT state and never terminating. ![]() MySQL allows a maximum of 100,000 connections. Network/Kernel issue: May be there is a network/kernel issue, which is preventing the connections from terminating. You can use the maxconnections flag to configure a connections limit. Here are the potential issues which could cause DB connection leak:ġ. Just keep in mind that the connection pool should be thread safe in a multi thread scenario.Greetings. A connection pool would keep a queue for the requests to access the database until a connection becomes available so it can proceed with processing the users request. This prevents the application from creating more connections that the server can handle, and not crashing the application to the users. While that may not cause any problems to some, the moment you have more visitors or some tasks that are database intensive and can run on multiple connections, the best way to prevent the server crashing with "TOO MANY CONNECTIONS" error is to implement a database connection pool. Select new Parameter group created and restart the instance or let AWS reboot it during next maintenance window. Restart MySQL service after save the configraion. yang2node1: sudo vi /etc/mysql/my.cnf mysqld character-set-serverutf8 collation-serverutf8generalci maxconnections1000. Then, I edit the configuration file of MySQL. I'm not an expert on Magento, but as I recently had a similar issue on a project I was working on, I noticed that the default implementation of the framework I was using created a connection with every call to the database. Create a new Parameter Group (AWS wil leave everything as default) search for the maxconnections value. As we can see, the variable value of maxconnections is 151. m2.xlarge 1412 m3.2xlarge 2492 r3.xlarge 2540 Referring by maxconnections at AWS RDS MySQL Instance Sizes in 2015. While increasing the max connections on the server config may fix the problem, you should consider verifying your application configurations and implementations. AWS RDS maxconnections limit variable is based on Instance type, so you can upgrade your RDS or make more replica.
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