2015-12-01 09:01:45,010 FATAL (EJB default - 7) class com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 13 973 milliseconds ago.  The last packet sent successfully to the server was 3 milliseconds ago.
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) [rt.jar:1.8.0_60]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) [rt.jar:1.8.0_60]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) [rt.jar:1.8.0_60]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:422) [rt.jar:1.8.0_60]
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1129)
	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3720)
	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3609)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4160)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2617)
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2778)
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2834)
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2156)
	at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2313)
	at org.jboss.jca.adapters.jdbc.WrappedPreparedStatement.executeQuery(WrappedPreparedStatement.java:462)
...
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
	at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3166)
	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3620)
	... 58 more

standalone-ha.xml (avant)

<subsystem xmlns="urn:jboss:domain:datasources:1.2">
            <datasources>
                <datasource jta="false" jndi-name="java:jboss/datasources/DsClient" pool-name="MySQLPoolDsScotClient" enabled="true" spy="false">
                    <connection-url>jdbc:mysql://mariadb.host:3306/database</connection-url>
                    <driver>mysql</driver>
                    <pool>
                        <max-pool-size>30</max-pool-size>
                    </pool>
                    <security>
                        <user-name>sql_user</user-name>
                        <password>sql_password</password>
                    </security>
                    <statement>
                        <track-statements>true</track-statements>
                        <share-prepared-statements>false</share-prepared-statements>
                    </statement>
                </datasource>
                <drivers>
                    <driver name="mysql" module="com.mysql">
                        <xa-datasource-class>com.mysql.jdbc.jdbc2.optional.MysqlXADataSource</xa-datasource-class>
                    </driver>
                </drivers>
            </datasources>
        </subsystem>
show variables like '%timeout%';
+-----------------------------+----------+
| Variable_name               | Value    |
+-----------------------------+----------+
| connect_timeout             | 10       |
| deadlock_timeout_long       | 50000000 |
| deadlock_timeout_short      | 10000    |
| delayed_insert_timeout      | 300      |
| innodb_flush_log_at_timeout | 1        |
| innodb_lock_wait_timeout    | 50       |
| innodb_rollback_on_timeout  | OFF      |
| interactive_timeout         | 28800    |
| lock_wait_timeout           | 31536000 |
| net_read_timeout            | 30       |
| net_write_timeout           | 60       |
| slave_net_timeout           | 3600     |
| thread_pool_idle_timeout    | 60       |
| wait_timeout                | 28800    |
+-----------------------------+----------+

Ressources :

standalone-ha.xml (après)

<subsystem xmlns="urn:jboss:domain:datasources:1.2">
            <datasources>
                <datasource jta="false" jndi-name="java:jboss/datasources/DsScotClient" pool-name="MySQLPoolDsClient" enabled="true" use-ccm="true" statistics-enabled="true">
                    <connection-url>jdbc:mysql://mariadb-ha.host:3306/database?disableLocalTxn=true</connection-url>
                    <driver-class>com.mysql.jdbc.Driver</driver-class>
                    <connection-property name="autoReconnect">
                        true
                    </connection-property>
                    <driver>com.mysql</driver>
                    <transaction-isolation>TRANSACTION_READ_COMMITTED</transaction-isolation>
                    <pool>
                        <max-pool-size>50</max-pool-size>
                        <flush-strategy>IdleConnections</flush-strategy>
                    </pool>
                    <security>
                        <user-name>sql_user</user-name>
                        <password>sql_password</password>
                    </security>
                    <validation>
                        <valid-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLValidConnectionChecker"/>
                        <check-valid-connection-sql>SELECT 1;</check-valid-connection-sql>
                        <validate-on-match>true</validate-on-match>
                        <background-validation>true</background-validation>
                        <background-validation-millis>3000</background-validation-millis>
                        <stale-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLStaleConnectionChecker"/>
                        <exception-sorter class-name="org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLExceptionSorter"/>
                    </validation>
                    <timeout>
                        <idle-timeout-minutes>0</idle-timeout-minutes>
                        <query-timeout>60</query-timeout>
                        <allocation-retry>2</allocation-retry>
                    </timeout>
                    <statement>
                        <track-statements>true</track-statements>
                        <prepared-statement-cache-size>100</prepared-statement-cache-size>
                        <share-prepared-statements>true</share-prepared-statements>
                    </statement>
                </datasource>
                <drivers>
                    <driver name="com.mysql" module="com.mysql">
                        <xa-datasource-class>com.mysql.jdbc.jdbc2.optional.MysqlXADataSource</xa-datasource-class>
                    </driver>
                </drivers>
            </datasources>
        </subsystem>