MySQL "Communications link failure Last packet sent to the server was 0 ms ago"

Solution Unverified - Updated -

Environment

  • JBoss Enterprise Application Platform (EAP)
    • 4.3.x
    • 5.x.x
    • 6.x.x
  • MySQL (any version)

Issue

  • Cannot connect to MySQL database from JBoss
  • Seeing below error message:
    org.jboss.resource.JBossResourceException: Could not create connection; - nested throwable: (com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
    Last packet sent to the server was 0 ms ago.)
          at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.getLocalManagedConnection(LocalManagedConnectionFactory.java:225)
          at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.createManagedConnection(LocalManagedConnectionFactory.java:195)
          at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.createConnectionEventListener(InternalManagedConnectionPool.java:611)
          at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.getConnection(InternalManagedConnectionPool.java:257)
          at org.jboss.resource.connectionmanager.JBossManagedConnectionPool$BasePool.getConnection(JBossManagedConnectionPool.java:607)
          at org.jboss.resource.connectionmanager.BaseConnectionManager2.getManagedConnection(BaseConnectionManager2.java:404)
          at org.jboss.resource.connectionmanager.TxConnectionManager.getManagedConnection(TxConnectionManager.java:381)
          at org.jboss.resource.connectionmanager.BaseConnectionManager2.allocateConnection(BaseConnectionManager2.java:496)
          at org.jboss.resource.connectionmanager.BaseConnectionManager2$ConnectionManagerProxy.allocateConnection(BaseConnectionManager2.java:941)
          at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:89)
          at org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider.getConnection(InjectedDataSourceConnectionProvider.java:46)
          ...
    Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure Last packet sent to the server was 0 ms ago.
          at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
          at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
          at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
          at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
          at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
          at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2103)
          at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)
          at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
          at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
          at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
          at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
          at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
          at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
          at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.getLocalManagedConnection(LocalManagedConnectionFactory.java:207)
          ... 71 more
    Caused by: java.net.ConnectException: Connection refused: connect
          at java.net.PlainSocketImpl.socketConnect(Native Method)
          at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
          at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
          at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
          at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
          at java.net.Socket.connect(Socket.java:525)
          at java.net.Socket.connect(Socket.java:475)
          at java.net.Socket.<init>(Socket.java:372)
          at java.net.Socket.<init>(Socket.java:215)
          at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:253)
          at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280)
          at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2026)
          ... 81 more

Resolution

See diagnostic steps and resolve any issues.

Diagnostic Steps

Verify

  • There are not any network connectivity issues
  • IP address or hostname in JDBC URL is wrong.
  • Hostname in JDBC URL is not recognized by local DNS server.
  • Port number is missing or wrong in JDBC URL.
  • DB server is down.
  • DB server doesn't accept TCP/IP connections.
  • DB server has run out of connections.
  • Something in between Java and DB is blocking connections, e.g. a firewall or proxy.

To solve the one or the other, follow the following advices:

  • Verify and test them with ping.
  • Refresh DNS or use IP address in JDBC URL instead.
  • Verify it based on my.cnf of MySQL DB.
  • Start the DB.
  • Verify if mysqld is started without the --skip-networking option.
  • Restart the DB and fix your code accordingly that it closes connections in finally.
  • Disable firewall and/or configure firewall/proxy to allow/forward the port.

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