Communications link failure with MySQL db


An error message may be appended to JBoss' 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, follow these steps:

  1. Increase the wait_timeout in mysql db setting file my.ini (Windows) or my.cnf (Linux). e.g. On Linux, modify the value in /etc/my.cnf file as below:


    Then, re-start mysql db.

  2. Add the hibernate properties shown below in 'MySQL-Default' master & staging in Talend MDM db setting file jboss-4.2.2.GA\bin\datasources.xml:

    <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>
Version history
Revision #:
10 of 10
Last update:
‎09-29-2018 12:16 AM
Updated by:
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