My webapp is running on Tomcat 5.5, I declared the datasource in web.xml:
<resource-ref>
<res-ref-name>jdbc/OrdiniWebDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
<res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>
In context.xml (tomcat conf):
<Resource
auth="Container"
driverClassName="com.mysql.jdbc.Driver"
maxActive="100"
maxIdle="30"
maxWait="10000"
name="jdbc/OrdiniWebDS"
password="[mypassword]"
type="javax.sql.DataSource"
url="jdbc:mysql://[myHost:port]/ordiniweb"
username="[myusername]"
/>
The database is a MySql 5.0. Everything works well except that sometimes, after several hours of "unuse", at first access I got this Exception:
com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.io.EOFException
STACKTRACE:
java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1956)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2368)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2867)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1616)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1708)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3255)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1293)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1428)
at org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
at com.blasetti.ordiniweb.dao.OrdiniDAO.caricaOrdine(OrdiniDAO.java:263)
...
** END NESTED EXCEPTION **
Last packet sent to the server was 0 ms ago.
com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2579)
com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2867)
com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1616)
com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1708)
com.mysql.jdbc.Connection.execSQL(Connection.java:3255)
com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1293)
com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1428)
org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
com.blasetti.ordiniweb.dao.OrdiniDAO.caricaOrdine(OrdiniDAO.java:263)
...
I need to refresh and it works well again. Any idea? Thanks.
MySQL drops unused connections after a while because it assumes that the other side forgot to close it.
What you need to do is to configure a check that Tomcat should apply before it reuses a pooled connection. To do this, add ?autoReconnect=true&useUnicode=true&characterEncoding=utf8
to the end of the URL and add validationQuery="Select 1"
to the Resource
element:
<Resource
auth="Container"
driverClassName="com.mysql.jdbc.Driver"
maxActive="100"
maxIdle="30"
maxWait="10000"
name="jdbc/OrdiniWebDS"
password="[mypassword]"
type="javax.sql.DataSource"
url="jdbc:mysql://[myHost:port]/ordiniweb?autoReconnect=true&useUnicode=true&characterEncoding=utf8"
username="[myusername]"
validationQuery="Select 1"
/>
[EDIT] This page gives more details: Configuring a MySQL Datasource in Apache Tomcat