Hello Youssef
My understanding was that Tomcat 6 uses a data source factory to
create the data source, and uses Jakarta Commons DBCP to supply a data
source factory and implement connection pooling.
My configuration of the javax.sql.DataSource mimics:
http://tomcat.apache.org/tomcat-6.0-doc/jndi-datasource-examples-howto.html#Database%20Connection%20Pool%20(DBCP)%20Configurations
I'll take a look at c3p0 and let you know how I get on.
Thanks
Tom
On 21/06/2008, at 1:50 PM, Youssef Mohammed wrote:
people were suffering from this exception in hibernate forums, it was
suggested to switch from DBCP to c3po.
Note also that the config you provided is not using any pooling at
all.
Datasources are not pooled by default.
On Sat, Jun 21, 2008 at 8:18 AM, Thomas Haines <
[EMAIL PROTECTED]> wrote:
Hello
I am experiencing a reproducible problem with connection pooling in
Tomcat,
although I suspect it is not a Tomcat issue per se.
I am running:
mysql server 5.0.58
tomcat 6.0.16
mysql connector 5.1.6
java version 1.5.0_13
all on CentOS 5
The following error occurs when there has been no activity between
the DB
and Tomcat for some period of time:
ERROR (21-06-08 07:59) [servlets.ViewEmail]
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last
packet
successfully received from the server was 46859 seconds ago.The
last packet
sent successfully to the server was 46859 seconds ago, which 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
problem.
at
sun.reflect.GeneratedConstructorAccessor17.newInstance(Unknown
Source)
at
sun
.reflect
.DelegatingConstructorAccessorImpl
.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:
513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at
com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:
1074)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3246)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1917)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:
2542)
at
com
.mysql
.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734)
at
com
.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:
1885)
at
org
.apache
.tomcat
.dbcp
.dbcp
.DelegatingPreparedStatement
.executeQuery(DelegatingPreparedStatement.java:93)
at
com.ghf.util.MailoutUtils.getRecipientbyChecksum(MailoutUtils.java:
123)
INFO (21-06-08 08:01) [servlets.ViewEmail] : View email request
successfully processed
INFO (21-06-08 08:02) [servlets.ViewEmail] : View email request
successfully processed
At this juncture, I am unsure how to remedy this. My only two
thoughts are
to either:
a) downgrade to MySQL Connector/J 5.0.8 and see if this fixes it;
b) add a while (!verified && attempts<2) type loop in getConnection()
method to query the DB using a minimal query and then catch the
first dead
connection.
I'm not overly keen on introducing the additional overhead of
querying the
DB just to check if it is valid every time a request is made for a
connection. Does anyone have any thoughts on how I might debug/
solve this
issue? I've searched widely on Google to no avail. Interestingly,
there is
another instance of tomcat communicating with MySQL on the machine,
exactly
the same configuration, that doesn't suffer these woes. Any help
would be
appreciated!
Tom
Other relevant snippets:
META-INF/context.xml:
<?xml version="1.0" encoding="UTF-8"?>
<Context path="/dyn">
<Resource name="jdbc/ghip" auth="Container"
type="javax.sql.DataSource"
maxActive="50"
maxIdle="5"
maxWait="10000"
username="******"
password="******"
driverClassName="com.mysql.jdbc.Driver"
removeAbandoned="true"
removeAbandonedTimeout="180"
url="jdbc:mysql://localhost:3306/ghip?autoReconnect=true"
/>
</Context>
DBPool.java exert:
/**
* Method getConnection.
* @return Connection New connection from the pool
*/
public static Connection getConnection() {
Connection conn = null;
try {
Context ctx = (Context) new
InitialContext().lookup("java:comp/env");
conn = ((DataSource)
ctx.lookup("jdbc/ghip")).getConnection();
}
catch (Exception e) {
e.printStackTrace(System.err);
}
return conn;
}
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