ConnectException using connection pool

[assauei]

Hi,

I have a servlet running on Tomcat 5.0, it uses
a connection pool and all goes right but sometimes
it crashes and when i shutdown it i get the following error:

Catalina.stop: java.net.ConnectException: Connection refused
java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
...

... and in the log file:

java.lang.NoClassDefFoundError: org/apache/commons/digester/Digester
at org.apache.webapp.balancer.RulesParser.createDigester(RulesParser.java:65)


i am new to Tomcat... can somebody help me?

 

[sedj]

Do you have the file TOMCAT_HOME/server/lib/commons-digester.jar ?

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk

 

[assauei]

Hi sedj,

yes, the file commons-digester.jar is in the TOMCAT_HOME/server/lib/ directory. i have temporary disabled the connection pool and all seems to run well, but this is not the solution, because i need the connection pool...
any idea?

 

[assauei]

This is the server.xml file:

<Context path="/MyPath" docBase="MyDocBase" debug="5" reloadable="true">

<Resource name="jdbc/TestDB"
auth="Container"
type="javax.sql.DataSource"/>

<ResourceParams name="jdbc/TestDB">
<parameter>
<name>factory</name>
<value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
</parameter>

<!-- Maximum number of dB connections in pool. Make sure you
configure your mysqld max_connections large enough to handle
all of your db connections. Set to 0 for no limit.
-->
<parameter>
<name>maxActive</name>
<value>20</value>
</parameter>

<!-- Maximum number of idle dB connections to retain in pool.
Set to -1 for no limit. See also the DBCP documentation on this
and the minEvictableIdleTimeMillis configuration parameter.
-->
<parameter>
<name>maxIdle</name>
<value>30000</value>
</parameter>

<!-- Maximum time to wait for a dB connection to become available
in ms, in this example 10 seconds. An Exception is thrown if
this timeout is exceeded. Set to -1 to wait indefinitely.
-->
<parameter>
<name>maxWait</name>
<value>100</value>
</parameter>

<parameter>
<name>removeAbandoned</name>
<value>true</value>
</parameter>
<parameter>
<name>removeAbandonedTimeout</name>
<value>60</value>
</parameter>


<!-- MySQL dB username and password for dB connections -->
<parameter>
<name>username</name>
<value>usr</value>
</parameter>
<parameter>
<name>password</name>
<value>pwd</value>
</parameter>

<!-- Class name for the old mm.mysql JDBC driver - uncomment this entry and comment next
if you want to use this driver - we recommend using Connector/J though
<parameter>
<name>driverClassName</name>
<value>org.gjt.mm.mysql.Driver</value>
</parameter>
-->

<!-- Class name for the official MySQL Connector/J driver -->
<parameter>
<name>driverClassName</name>
<value>com.mysql.jdbc.Driver</value>
</parameter>

<!-- The JDBC connection url for connecting to your MySQL dB.
The autoReconnect=true argument to the url makes sure that the
mm.mysql JDBC Driver will automatically reconnect if mysqld closed the
connection. mysqld by default closes idle connections after 8 hours.
-->
<parameter>
<name>url</name>
<value>jdbc:mysql://localhost/MyDatabase</value>
</parameter>
</ResourceParams>
</Context>

... and the web.xml file:

<web-app xmlns="

http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="

http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="

http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"

version="2.4">
<description>MySQL Test App</description>
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>


...finally in my servlet:

Connection conn = null;
PreparedStatement pstmt = null;
InitialContext initCtx = null;
try {
initCtx = new InitialContext();
DataSource ds = (DataSource)initCtx.lookup("java:comp/env/jdbc/...");
conn = ds.getConnection();

...

This code runs, but sometimes the application crashes and the server blocks... i really don't know what is the problem.

 

[sedj]

Are you sure that you are closing the connection correctly, and ensuring there are no leaks ?

You should always close the connection in a finally block (and check that it is not null before closing) so that even if an exception happens whilst you are using the connection, that it is closed.

Without seeing a stack trace of the error or more detail, its hard to guess what is the cause of "application crashes" or "server blocks" ...

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk

 

[assauei]

That is the stack trace:

Catalina.stop: java.net.ConnectException: Connection refused
java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.PlainSocketImpl.connect(SocksSocketImpl.java:364)
at java.net.Socket.connect(Socket.java:507)
at java.net.Socket.connect(Socket.java:457)
at java.net.Socket.<init>(Socket.java:365)
at java.net.Socket.<init>(Socket.java:178)
at org.apache.catalina.startup.Catalina.stopServer(Catalina.java:410)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelagatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.stopServer(Bootstrap.java:336)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:427)


... and in the log file:

java.lang.NoClassDefFoundError: org/apache/commons/digester/Digester
at org.apache.webapp.balancer.RulesParser.createDigester(RulesParser.java:65)
at org.apache.webapp.balancer.RulesParser.<init>(RulesParser.java:43)
at org.apache.webapp.balancer.BalancerFilter.init(BalancerFilter.java:79)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:225)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:308)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:79)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3698)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4349)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:823)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:807)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:595)
at org.apache.catalina.core.StandardHostDeployer.install(StandardHostDeployer.java:277)
at org.apache.catalina.core.StandardHost.install(StandardHost.java:832)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:701)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:432)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:983)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:349)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1091)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:789)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1083)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:478)
at org.apache.catalina.core.StandardService.start(StandardService.java:480)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2313)
at org.apache.catalina.startup.Catalina.start(Catalina.java:556)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:287)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)

 

[sedj]

Whats that "connection refused" error got to do with JDBC ? From the look of that stack trace, that is tomcat trying to shutdown, and not being able to contact the local server's shutdown hook.

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk