How to Fix "com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections" "

Reason for this error

This error occurs when number of concurrent connections used in the product exceeds the maximum number of connections defined in the database.

Fix

In MySQL, you can use below command to check the maximum number of concurrent connections.

mysql> show variables like 'max_connections';

+-----------------+-------+

| Variable_name   | Value |

+-----------------+-------+

| max_connections | 151   |

+-----------------+-------+

1 row in set (0.00 sec)

If you want to change the maximum number of concurrent connections in the database,

1. Open 'my.cnf' file located in /etc/mysql folder.
2. Change set the number of maximum concurrent connections you need to have to 'max_connections' property.
3. Restart mysql.

Error

 ERROR - TransactionManager Failed to start new registry transaction.

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.

at sun.reflect.GeneratedConstructorAccessor66.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.Util.getInstance(Util.java:387)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:898)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:887)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:862)

at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2164)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2089)

at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:795)

at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:44)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)

at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:278)

at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:182)

at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:701)

at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:635)

at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:188)

at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:128)

at org.wso2.carbon.registry.core.jdbc.dataaccess.JDBCTransactionManager.beginTransaction(JDBCTransactionManager.java:80)

at org.wso2.carbon.registry.core.jdbc.EmbeddedRegistry.beginTransaction(EmbeddedRegistry.java:443)

at org.wso2.carbon.registry.core.jdbc.EmbeddedRegistry.resourceExists(EmbeddedRegistry.java:631)

at org.wso2.carbon.registry.core.session.UserRegistry.resourceExistsInternal(UserRegistry.java:774)

at org.wso2.carbon.registry.core.session.UserRegistry.access$800(UserRegistry.java:61)

at org.wso2.carbon.registry.core.session.UserRegistry$9.run(UserRegistry.java:757)

at org.wso2.carbon.registry.core.session.UserRegistry$9.run(UserRegistry.java:754)

at java.security.AccessController.doPrivileged(Native Method)

at org.wso2.carbon.registry.core.session.UserRegistry.resourceExists(UserRegistry.java:754)

at org.wso2.carbon.registry.core.jdbc.handlers.builtin.MountHandler.get(MountHandler.java:392)

at org.wso2.carbon.registry.core.jdbc.handlers.HandlerManager.get(HandlerManager.java:2444)

at org.wso2.carbon.registry.core.jdbc.handlers.UserDefinedHandlerManager.get(UserDefinedHandlerManager.java:200)

at org.wso2.carbon.registry.core.jdbc.handlers.HandlerLifecycleManager.get(HandlerLifecycleManager.java:914)

at org.wso2.carbon.registry.core.jdbc.EmbeddedRegistry.get(EmbeddedRegistry.java:512)

at org.wso2.carbon.registry.core.caching.CacheBackedRegistry.get(CacheBackedRegistry.java:203)

at org.wso2.carbon.registry.core.session.UserRegistry.getInternal(UserRegistry.java:617)

at org.wso2.carbon.registry.core.session.UserRegistry.access$400(UserRegistry.java:61)

at org.wso2.carbon.registry.core.session.UserRegistry$5.run(UserRegistry.java:597)

at org.wso2.carbon.registry.core.session.UserRegistry$5.run(UserRegistry.java:594)

at java.security.AccessController.doPrivileged(Native Method)

at org.wso2.carbon.registry.core.session.UserRegistry.get(UserRegistry.java:594)

at org.wso2.carbon.registry.indexing.AsyncIndexer$IndexingTask.createIndexDocument(AsyncIndexer.java:242)

at org.wso2.carbon.registry.indexing.AsyncIndexer$IndexingTask.run(AsyncIndexer.java:210)

at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)

at java.util.concurrent.FutureTask.run(FutureTask.java:262)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)

at java.lang.Thread.run(Thread.java:745)

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection,  message from server: "Too many connections"

at sun.reflect.GeneratedConstructorAccessor66.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.Util.getInstance(Util.java:387)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:898)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:887)

at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1038)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2254)

at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2105)

... 44 more

[2017-05-08 11:20:47,779] ERROR - TransactionManager Failed to start new registry transaction.

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.

at sun.reflect.GeneratedConstructorAccessor66.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.Util.getInstance(Util.java:387)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:898)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:887)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:862)

at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2164)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2089)

at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:795)

at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:44)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)