Connecting Tomcat container to mysql container: JDBCConnectionException: Unable to acquire JDBC Connection - mysql

Question

I'm trying to port my web-app created on Windows, using Hibernate, XAMPP for Apache tomcat and mysql server, to Linux, using Docker. I've deployed my war file under webapps folder on tomcat container, linked to mysql container ... the fact is that my web app is very very slow: i.e., the first feature is login/register form: on Linux, there is latency about minutes!
I've created containers with the following commands:
docker run -d --name mysql-phpmyadmin -p 127.0.0.1:8686:80 -p 127.0.0.1:3306:3306 grzesiekb/mysql-phpmyadmin
docker run -d -p 8484:8080 -p 8007:8009 --name tomcat8-linked --link mysql-phpmyadmin:mysqlphp tomcat:8.0-jre8
This is my hibernate.cfg.xml file:
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- queste configurazioni sono per il testing in locale -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://mysqlphp:3306/at_db</property>
<property name="hibernate.connection.username">root</property>
<property name="connection.password">mysql_pass</property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="show_sql">false</property>
<!--<property name="hibernate.hbm2ddl.auto">create-drop</property> se al posto di update metto create, mi cancella il db e lo rifa -->
<property name="hbm2ddl.auto">update</property>
<!-- Entity -->
<mapping class="com.ATBoscoCastellano.Entity.ClientUser" />
<mapping class="com.ATBoscoCastellano.Entity.GenericUser" />
<mapping class="com.ATBoscoCastellano.SessionManagement.SessionToken" />
<mapping class="com.ATBoscoCastellano.Entity.Post" />
<!-- <mapping class="it.boscus.StarFoods.entity.ExampleEmbeddableIDClass2" /> -->
</session-factory>
</hibernate-configuration>
And this is what I see from tomcat logs:
20-Feb-2017 07:48:15.869 SEVERE [http-apr-8080-exec-3] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [com.ATBoscoCastellano.servlets.UserSessionServlet] in context with path [/AtApplicazione1] threw exception
org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:115)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
....
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 232,149,705 milliseconds ago. The last packet sent successfully to the server was 232,149,705 milliseconds ago. is longer than the server configured
value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this probl
em.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:983)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3644)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2452)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2617)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2546)
at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:4873)
at org.hibernate.engine.jdbc.connections.internal.PooledConnections.poll(PooledConnections.java:76)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.getConnection(DriverManagerConnectionProviderImpl.java:187)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:386)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:84)
... 34 more
Caused by: java.net.SocketException: Broken pipe (Write failed)
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
at java.net.SocketOutputStream.write(SocketOutputStream.java:155)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
I've tried adding autoReconnect=true on Url in hibernate, but still doesn't work. In my mysql my.cnf there is no wait_timeout line.
I have to tell that web-app works, but i attend a lot of time (tens of minutes) after my servlet (that interacts via hibernate with mysql container) works. This servlet, that manages login/register form, checks from the db the eventual presence of the inserted credentials.
I have tomcat container based on tomcat8.0-jre8 official docker image;
From mysql -V I have
root#1c53f40b63d3:/var/log/mysql# mysql -V
mysql Ver 14.14 Distrib 5.5.42, for debian-linux-gnu (x86_64) using readline 6.3
I really don't know why on Windows it works perfectly, but here not. My servlet remain in "pending" state ... i really want to know why there is so spending in time and how to solve it.