Communications link failure with MySQL db


An error message may be appended to JBoss's log file while using Talend MDM (Master Data Management) with MySQL DB. This article describes this error and provides solutions to eliminate it.


When using Talend MDM with MySQL DB, the following error may occur several times in the jboss server log file jboss-4.2.2.GA\server\default\log\server.log.

MESSAGE: Communications link failure
Last packet sent to the server was 1 ms ago.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Last packet sent to the server was 1 ms ago.
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(
	at java.lang.reflect.Constructor.newInstance(
	at com.mysql.jdbc.Util.handleNewInstance(
	at com.mysql.jdbc.SQLError.createCommunicationsException(
	at com.mysql.jdbc.MysqlIO.send(
	at com.mysql.jdbc.MysqlIO.sendCommand(
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(
	at com.mysql.jdbc.ConnectionImpl.execSQL(
	at com.mysql.jdbc.PreparedStatement.executeInternal(



To resolve the problem, please do the following steps:

  • Increase thewait_timeout in the MySQL db setting file my.ini (Windows) or my.cnf (Linux). For example, on Linux modify the value in your /etc/my.cnf file as follows:


    Then re-start the MySQL db.

  • Add the following hibernate properties in MySQL-Default master & staging in the Talend MDM db setting file jboss-4.2.2.GA\bin\datasources.xml, such as:

    <datasource name="MySQL-Default">
            <property name="connection.autoReconnect">true</property>
            <property name="connection.autoReconnectForPools">true</property>
           	<property name="">true</property>
            <property name="hibernate.c3p0.acquire_increment">1</property>
            <property name="hibernate.c3p0.idle_test_period">0</property>
            <property name="hibernate.c3p0.timeout">0</property>
            <property name="hibernate.c3p0.validate">true</property>
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Last update:
‎06-16-2017 12:02 PM
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