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java:thelastpacketsuccessfullyreceivedfromserver [2013/10/02 07:24] – rlunarojava:thelastpacketsuccessfullyreceivedfromserver [2022/12/02 21:02] (current) – external edit 127.0.0.1
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   * Mysql worked perfectly   * Mysql worked perfectly
   * There wasn't a network error   * There wasn't a network error
-  * So... what the problem were???+  * So... were the problem is???
  
 ==== My architecture ==== ==== My architecture ====
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   * A batch application that runs for hours and then stops. It only have one thread: starts, do thounsands of queries and then stops.   * A batch application that runs for hours and then stops. It only have one thread: starts, do thounsands of queries and then stops.
  
 +If you have the same problem, but in a web application, this please read on; some of the things described here are still useful or at least you should check them out.
 ===== First approach: retention of Session objects ===== ===== First approach: retention of Session objects =====
  
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 </code> </code>
  
-**An this is wrong.** The [[http://docs.spring.io/spring/docs/2.5.x/api/org/springframework/orm/hibernate3/HibernateTemplate.html|HibernateTemplate]] object must be declared singleton. This saves lots of session objects and keep them alive because they are always been called across the application. +**An this is wrong.** The [[http://docs.spring.io/spring/docs/2.5.x/api/org/springframework/orm/hibernate3/HibernateTemplate.html|HibernateTemplate]] object must be declared singleton (maybe "session" in a web application to avoid multithreading issues). This saves lots of session objects and keep them alive because they are always been called across the application. 
  
 However, I am starting to think that HibernateTemplate doesn't close properly it's Session objects. If this were the case, it will explain why when I release my HibernateTemplate objects the corresponding session objects weren't released and closed.  However, I am starting to think that HibernateTemplate doesn't close properly it's Session objects. If this were the case, it will explain why when I release my HibernateTemplate objects the corresponding session objects weren't released and closed. 
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 +===== My final configuration of Spring =====
  
 +First, define C3P0 datasource:
  
 +<code>
 +   <!--
 +   A better datasource: it gives a new connection each time
 +   is requested.
 +   -->
 +   <bean id="dataSource"
 +         class="com.mchange.v2.c3p0.ComboPooledDataSource"
 +         destroy-method="close"
 +         scope="singleton">
 +      <!--
 +      To test a connection:
 +      mysql -h HOSTNAME -u USERNAME -p
 +      and aftwerwards introduce the password when requested
 +
 +       -->
 +      <property name="driverClass" value="com.mysql.jdbc.Driver"/>
 +      <property name="jdbcUrl"     value="jdbc:mysql://${mysql-server}:${mysql-port}/${mysql-database}"/>
 +      <property name="user"        value="${mysql-user}"/>
 +      <property name="password"    value="${mysql-password}"/>
 +      <!--
 +      Recommended values for maxPoolSize and minPoolSize:
 +          1. get value of max available connections of your
 +             database issuing command 'show variables like "max_connections";'
 +          2. this will be the upper limit for maxPoolSize: you shouldn't
 +             reach never this limit
 +          3. check out with show processlist the active connections
 +             to the database: this will help to determine the available
 +             connections for your application:
 +             (show processlist) - (show variables like max_connections)
 +          4. it is advisable to identify how many DAO objects will be
 +             issuing sentences to the database at the same time. Ok,
 +             make a rough stimation. Say that this value will be
 +             10. A good and steady value for maxPoolSize can
 +             be 40 (four times).
 +
 +       -->
 + <property name="maxPoolSize"         value="10"/>
 + <property name="minPoolSize"         value="5"/>
 + <!--
 + checkoutTimeout mits how long a client will wait for a
 + Connection, if all Connections are checked out and one
 + cannot be supplied immediately. In milliseconds.
 + http://www.mchange.com/projects/c3p0/#checkoutTimeout
 + -->
 + <property name="checkoutTimeout"     value="10000"/>
 + <property name="acquireIncrement"    value="1"/>
 + <property name="idleConnectionTestPeriod" value="100"/>
 + <!-- property name="preferredTestQuery"  value="select 1"/ -->
 + <!--
 + testConnectionOnCheckout is not recommended because it
 + checks the connection before give it to hibernate. In a
 + paranoid environment could fix some problems
 + -->
 + <!-- property name="testConnectionOnCheckout" value="true"/-->
 + <!--
 + debugUnreturnedConnectionStackTraces prints a stack trace when
 + a connection that is given to hibernate reachs its timeout value.
 + This could help to debug cases when a connection is taken and
 + not released in a certain amount of time
 + http://www.mchange.com/projects/c3p0/#debugUnreturnedConnectionStackTraces
 + -->
 + <!-- property name="debugUnreturnedConnectionStackTraces" value="true"/-->
 + <!--
 + unreturnedConnectionTimeout is the silver bullet for a problem in
 + a greedy application (in terms of sessions). It will count how long
 + hibernate has taken a connection, and if reachs a timeout, c3p0 will
 + replace this connection with a fresh session, avoiding the problem
 + of the database may close opened for much time
 + http://www.mchange.com/projects/c3p0/#unreturnedConnectionTimeout
 + -->
 + <!--property name="unreturnedConnectionTimeout" value="100"/-->
 +   </bean>
 +
 +</code>
 +
 +
 +Second, the hibernateTemplate and jdbctemplate objects of spring will be available accross the application.
 +**Beware!!! If you are developing a web application, these should be session instead of singleton!!!**
 +
 +
 +<code xml>
 +   <bean id="simpleJdbcTemplate"
 +         class="org.springframework.jdbc.core.simple.SimpleJdbcTemplate"
 +         scope="singleton">
 +     <constructor-arg ref="dataSource"/>
 +   </bean>
 +
 +    <bean id="hibernateTemplate"
 +          class="org.springframework.orm.hibernate3.HibernateTemplate"
 +          scope="singleton">
 +        <property name="sessionFactory" ref="sessionFactory"/>
 +    </bean>
 +
 +</code>
 +
 +Finally, the sessionFactory:
 +
 +<code xml>
 +    <bean id="sessionFactory"
 +          class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"
 +          scope="singleton">
 +        <property name="dataSource" ref="dataSource"/>
 +        <property name="annotatedClasses">
 +            <list>
 +                <value>com.mapfre.dga.mercurio.entity.Detail</value>
 +                <value>com.mapfre.dga.mercurio.entity.Indicator</value>
 +                <value>com.mapfre.dga.mercurio.entity.Period</value>
 +                <value>com.mapfre.dga.mercurio.entity.Struct</value>
 +                <value>com.mapfre.dga.mercurio.entity.Valoration</value>
 +                <value>com.mapfre.dga.mercurio.entity.Version</value>
 +            </list>
 +        </property>
 +        <property name="hibernateProperties">
 +            <props>
 +                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
 +                <!-- for debug, put these values to "true" -->
 +                <prop key="hibernate.show_sql">${show-sql-in-hibernate}</prop>
 +                <prop key="hibernate.format_sql">${format-sql-in-hibernate}</prop>
 +
 +                <!--
 +                Possible values for this are:
 +                     on_close : legacy behavior. The session gets the connection when
 +                                the first time it requires it and release it when it's
 +                                destroyed
 +                     after_transaction :
 +                                session is released after Transaction issues a commit or
 +                                rollback
 +                     after_statement :
 +                                connection is released after execution of every statement,
 +                                BUT it will keep the connection open if the object
 +                 -->
 +                <!-- prop key="hibernate.connection.release_mode">after_statement</prop -->
 +            </props>
 +        </property>
 +    </bean>
 +
 +</code>
 +
 +I've put plenty of comments of useful configuration parameters and lots of information, just in case. 
 +
 +===== Resources =====
 +
 +http://www.mchange.com/projects/c3p0/
  
  
 ~~DISQUS~~ ~~DISQUS~~
java/thelastpacketsuccessfullyreceivedfromserver.1380698677.txt.gz · Last modified: 2022/12/02 21:02 (external edit)