我怎样才能防止Hibernate + c3p0 + MySql创建大量的睡眠连接？ [英] How can I prevent Hibernate + c3p0 + MySql creating large numbers of sleeping connections?

问题描述

我使用GWT和Hibernate，c3p0和MySQL来制作一个受限用户的网络应用程序（每天最多50个用户）。在测试过程中，我发现Hibernate与每个会话都打开一个连接，但不会关闭它，无论使用 close（）方法。

我目前的配置如下：

  hibernate.connection.driver_class = com.mysql.jdbc.Driver 
 hibernate.connection.url = 
 hibernate.connection.username = 
 hibernate.connection.password = 
 hibernate.dialect = org.hibernate.dialect.MySQLDialect 
 hibernate .current_session_context_class =线程
 hibernate.c3p0.min_size = 1 
 hibernate.c3p0.max_size = 1 
 hibernate.c3p0.timeout = 10 
 hibernate.c3p0.max_statements = 50 
 hibernate.c3p0.idle_test_period = 10 
 hibernate.c3p0.unreturned_connection_timeout = 1 
 hibernate.connection.provider_class = org.hibernate.connection.C3P0ConnectionProvider 
  

每创建一个新的连接池，都会创建一个新池。例如，如果我将池大小设置为3，则应用程序的2个连接将导致6个连接，直到应用程序关闭。

预期的行为是简单地关闭或重用每次交易后的连接。我怎样才能实现这个目标？在测试过程中，我发现Hibernate打开了每个连接的连接会话，但不关闭它，而不管使用close（）方法

当使用连接池时，调用 Connection＃close（）不会在物理上关闭连接，而是将其返回到池以供将来重用。换句话说，连接保持开放，这就是使用池的全部要点。

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我调用以下代码：AnnotationConfiguration（）。buildSessionFactory（）。getCurrentSession（）;

好的，这就是问题所在。您一遍又一遍地创建一个 SessionFactory （每个创建自己的池），而您应该在应用程序的整个生命周期内只创建一次。如果你没有使用任何特定的框架，这通常在一些实用工具类（着名的 HibernateUtil 类）中完成。

官方 Hibernate教程有这样一个类的非常基本的例子。或者参阅这一个，这有点丰富。

I'm using GWT with Hibernate, c3p0 and MySQL to produce a web app with a limited audience (max 50 users per day). During testing I found that Hibernate was opening a connection with each session but not closing it, irrespective of use of the close() method.

My current configuration is as follows:

hibernate.connection.driver_class=com.mysql.jdbc.Driver
hibernate.connection.url=
hibernate.connection.username=
hibernate.connection.password=
hibernate.dialect=org.hibernate.dialect.MySQLDialect
hibernate.current_session_context_class=thread
hibernate.c3p0.min_size=1
hibernate.c3p0.max_size=1
hibernate.c3p0.timeout=10
hibernate.c3p0.max_statements=50
hibernate.c3p0.idle_test_period=10
hibernate.c3p0.unreturned_connection_timeout=1
hibernate.connection.provider_class=org.hibernate.connection.C3P0ConnectionProvider

With each new connection to the application a new pool is created. For example if I set the pool size to 3, 2 connections to the application result in 6 connections until the application is closed.

The intended behaviour is to simply close or reuse the connections after each transaction. How can I achieve this?

解决方案

During testing I found that Hibernate was opening a connection with each session but not closing it, irrespective of use of the close() method

When using a connection pool, calling Connection#close() doesn't physically close the connection but return it to the pool for future reuse. In other words, the connection stays open and that's the whole point of using a pool.

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I call the following: AnnotationConfiguration().buildSessionFactory().getCurrentSession();

Well, that's the problem. You are creating a SessionFactory over and over (each creating its own pool) while you should create it only once for the lifetime of your application. If you are not using any particular framework, this is typically done in some utility class (the famous HibernateUtil class).

The official Hibernate Tutorial has a very basic example of such a class. Or see this one which is a bit richer.

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