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From "g. rgar" <the.u...@gmail.com>
Subject tomcat eclipse and too many connections
Date Sun, 14 Oct 2012 19:14:53 GMT
I am developing a small java ee app (java 1.7, eclipse juno, tomcat 7.0.30,
windows 7 professional, mysql-connector-java-5.1.22-bin.jar, vanilla
servlets/jsp MVC)

All works fine - while I change things and save .java files in eclipse it
apparently redeploys the app on Tomcat - after some redeployments I get :

com.mysql.jdbc.exceptions.
jdbc4.MySQLNonTransientConnectionException: Data source rejected
establishment of connection,  message from server: "Too many connections"

WARNING: Unexpected exception resolving reference
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data
source rejected establishment of connection,  message from server: "Too
many connections"
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
    at com.mysql.jdbc.Util.getInstance(Util.java:382)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1116)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2338)
    at
com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    at sun.reflect.GeneratedConstructorAccessor22.newInstance(Unknown
Source)
    at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378)
    at
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
    at
org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:278)
    at
org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:182)
    at
org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:699)
    at
org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:631)
    at
org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:485)
    at
org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:143)
    at
org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:116)
    at
org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:103)
    at
org.apache.tomcat.jdbc.pool.DataSourceFactory.createDataSource(DataSourceFactory.java:539)
    at
org.apache.tomcat.jdbc.pool.DataSourceFactory.getObjectInstance(DataSourceFactory.java:237)
    at
org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:143)
    at
javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:321)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:843)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:154)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:831)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:168)
    at
org.apache.catalina.core.NamingContextListener.addResource(NamingContextListener.java:1061)
    at
org.apache.catalina.core.NamingContextListener.createNamingContext(NamingContextListener.java:671)
    at
org.apache.catalina.core.NamingContextListener.lifecycleEvent(NamingContextListener.java:270)
    at
org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at
org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at
org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5173)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at
org.apache.catalina.core.StandardContext.reload(StandardContext.java:3920)
    at
org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:426)
    at
org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1345)
    at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1530)
    at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1540)
    at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1540)
    at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1519)
    at java.lang.Thread.run(Thread.java:722)


I suspect the data source is not closed properly **on redeployment** - I
have no probs while keeping the app open. I am able to replicate the
behavior by just touching the files and never once open the app in the
browser or do anything in my app (involving DB access)


context.xml :
<pre>
<?xml version="1.0" encoding="UTF-8"?>
<Context antiJARLocking="true" path="/ted2012">
    <Resource name="jdbc/TestDB" auth="Container"
type="javax.sql.DataSource"
        maxActive="100" maxIdle="30" maxWait="10000" username="root"
        password="root"
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
        driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/ted2012?useUnicode=yes&amp;characterEncoding=UTF-8"
        removeAbandoned="true" removeAbandonedTimeout="60" />
</Context>
</pre>

Pool class :

<pre>
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;

class DBConnectionPool {

    private DataSource ds = null;

    private DBConnectionPool() {
        try {
            Context context = new InitialContext();
            Context envctx = (Context) context.lookup("java:comp/env");
            ds = (DataSource) envctx.lookup("jdbc/TestDB");
        } catch (Exception e) {
            e.printStackTrace(); // TODO
        }
    }

    private static enum PoolSingleton {
        POOL_INSTANCE;

        private static final DBConnectionPool singleton = new
DBConnectionPool();

        private DBConnectionPool getSingleton() {
            return singleton;
        }
    }

    private static DBConnectionPool getDBConnectionPoolInstance() {
        return PoolSingleton.POOL_INSTANCE.getSingleton();
    }

    static Connection getConnection() {
        try {
            return getDBConnectionPoolInstance().ds.getConnection();
        } catch (SQLException e) {
            e.printStackTrace(); // TODO
            return null;
        }
    }

    static void freeConnection(Connection c) {
        try {
            c.close();
        } catch (SQLException e) {
            e.printStackTrace(); // TODO
        }
    }

    /**
     * This is intended to be used in finally blocks and therefore MUST NOT
     * THROW. See :
http://today.java.net/article/2006/04/04/exception-handling-
     * antipatterns
     *
     * @param set
     * @param statement
     * @param conn
     */
    static void closeResources(ResultSet set, Statement statement,
            Connection conn) {
        if (set != null) {
            try {
                set.close();
            } catch (SQLException e) {
                e.printStackTrace(); // TODO
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace(); // TODO
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace(); // TODO
            }
        }
    }
}

</pre>

I do close connections/ results/ statement (using the closeResources - I
never get too many connections if I do not redeploy - let me know if it is
an eclipse problem

Please get back to me if you need any more logs/traces etc

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