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POMany threads created using C3P0 with Hibernate/Spring
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  1. POMany threads created using C3P0 with Hibernate/Spring
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    copied!<p>I do a project merging Hibernate and Spring in a Java web application, using Tomcat under Linux environment. Due to the Mysql 8 hours timeout problem, we want to use C3P0 to manage a connection pool with our Mysql database. But when we use it, we have numerous threads that are created. I figured it out beacause I did on each request a print of all of them with a memory status that show me the increasing memory and that kind of threads:</p> <blockquote> <ul> <li>name: C3P0PooledConnectionPoolManager[identityToken->1hged7o8r13kpj7n1h3ycia|39c446]-HelperThread-#0 daemon: true group! main groupParent: system alive: true interrupted: false</li> <li>name: C3P0PooledConnectionPoolManager[identityToken->1hged7o8r13kpj7n1h3ycia|17ec0e8]-AdminTaskTimer daemon: true group! main groupParent: system alive: true interrupted: false</li> </ul> </blockquote> <p>It can produce more than 500 threads like these ones, after enough time.</p> <p>Here is my Hibernate.cfg.xml:</p> <pre><code> &lt;property name="connection.provider_class"&gt; org.hibernate.connection.C3P0ConnectionProvider&lt;/property&gt; &lt;property name="hibernate.c3p0.acquire_increment"&gt;1&lt;/property&gt; &lt;property name="hibernate.c3p0.idle_test_period"&gt;5&lt;/property&gt; &lt;property name="hibernate.c3p0.max_size"&gt;100&lt;/property&gt; &lt;property name="hibernate.c3p0.max_statements"&gt;100&lt;/property&gt; &lt;property name="hibernate.c3p0.min_size"&gt;10&lt;/property&gt; &lt;property name="hibernate.c3p0.timeout"&gt;5&lt;/property&gt; &lt;property name="hibernate.dialect"&gt;org.hibernate.dialect.MySQLDialect&lt;/property&gt; &lt;property name="hibernate.connection.driver_class"&gt;com.mysql.jdbc.Driver&lt;/property&gt; &lt;property name="hibernate.connection.url"&gt;jdbc:mysql://localhost:3306/myBase&lt;/property&gt; &lt;property name="hibernate.connection.username"&gt;root&lt;/property&gt; &lt;property name="hibernate.connection.password"&gt;&lt;/property&gt; &lt;property name="hibernate.hbm2ddl.auto"&gt;update&lt;/property&gt; &lt;property name="hibernate.default_schema"&gt;myProject&lt;/property&gt; &lt;property name="hibernate.query.factory_class"&gt;org.hibernate.hql.classic.ClassicQueryTranslatorFactory&lt;/property&gt; &lt;property name="show_sql"&gt;false&lt;/property&gt; &lt;property name="cache.provider_class"&gt; org.hibernate.cache.NoCacheProvider &lt;/property&gt; </code></pre> <p>I also tried to add a C3P0 propeties file, but except reducing the helper thread number, it don't delete the unsused thread:</p> <pre><code> c3p0.maxStatements=5 c3p0.maxIdleTime=10 c3p0.numHelperThreads=1 c3p0.testConnectionOnCheckout=true c3p0.preferredTestQuery=SELECT 1 c3p0.initialPoolSize=1 c3p0.minPoolSize=1 c3p0.maxPoolSize=10 c3p0.acquireIncrement=1 c3p0.idleConnectionTestPeriod=1 </code></pre> <p>Does anyone have an idea of why this happen and how to solve this problem? </p> <p>Thanks a lot.</p>
 

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