我正在使用Hibernate属性来定义连接池大小，以及LocalSessionFactoryBean和DriverManagerDataSource来创建org.hibernate.SessionFactory，我正在观察1000个TCP连接被打开到数据库服务器而不是我预期的连接池大小的上限。
设置连接Hibernate池的代码如下所示。请注意最大大小为100，但是我正在观察从我的工作站到数据库服务器的1000个连接 - 我在Windows机器上使用TCPView连接到由Vagrant（VirtualBox）管理的Centos OS VM上的MariabDB实例
Properties hibernateProperties = new Properties();
hibernateProperties.put("hibernate.dialect", "org.hibernate.dialect.MySQL5InnoDBDialect");
hibernateProperties.put("hibernate.show_sql", false);
hibernateProperties.put("hibernate.generate_statistics", false);
hibernateProperties.put("hibernate.hbm2ddl.auto", "update");
hibernateProperties.put("hibernate.use_sql_comments", false);
hibernateProperties.put("hibernate.c3p0.min_size", 10);
hibernateProperties.put("hibernate.c3p0.max_size", 100);
hibernateProperties.put("hibernate.c3p0.timeout", 1500);
hibernateProperties.put("hibernate.c3p0.max_statements", 5000);
hibernateProperties.put("hibernate.c3p0.idle_test_period", 60);
LocalSessionFactoryBean localSessionFactoryBean = new LocalSessionFactoryBean();
localSessionFactoryBean.setDataSource(dataSource);
localSessionFactoryBean.setHibernateProperties(hibernateProperties);
localSessionFactoryBean.setMappingResources("job.persistence.xml");
我希望看到这些连接最大值为100，并在以后执行循环时重复使用，但我观察超过1000次坐在TIME_WAIT中大约一分钟才关闭它们。以下是TCPView输出的示例：
[System Process] 0 TCP localhost 62794 192.168.98.102 3306 TIME_WAIT
[System Process] 0 TCP localhost 62796 192.168.98.102 3306 TIME_WAIT
[System Process] 0 TCP localhost 62797 192.168.98.102 3306 TIME_WAIT
[System Process] 0 TCP localhost 62795 192.168.98.102 3306 TIME_WAIT
[System Process] 0 TCP localhost 62798 192.168.98.102 3306 TIME_WAIT
[System Process] 0 TCP localhost 62801 192.168.98.102 3306 TIME_WAIT
我显然做错了什么但不确定是什么。我使用Spring来管理提供数据访问逻辑的DAO。 DAO被注册为原型Spring范围，而Singleton SessionFactory被注入到DAO中，如下所示：
@Bean(name="jobDao")
@Scope(SpringBeanScope.Prototype)
public JobDao jobDao(SessionFactory jobSessionFactory) { //...}
在DAO中，我正在调用sessionFactory.getCurrentSession()来访问数据库会话。以下是通用DAO基础的摘录，用于演示：
protected Session currentSession() {
return sessionFactory.getCurrentSession();
}
@Transactional
@Override
public void Add(TEntity entity) {
currentSession().save(entity);
}
当连接池限制为100时，有谁知道为什么要打开这么多TCP连接？
更新
由于此问题出现在Windows开发计算机上，因此我将一个小型.NET控制台应用程序放在一起，该应用程序使用并行for循环执行简单的SQL select语句，最大线程数为64，每次都创建一个新连接：
public void Test()
{
ParallelOptions options = new ParallelOptions();
options.MaxDegreeOfParallelism = 64;
Parallel.For(0,
1000,
options,
(i, state) =>
{
ExecuteSql();
});
}
private void ExecuteSql()
{
SqlDataAdapter adapter = new SqlDataAdapter(sql, new SqlConnection(connectionString));
DataSet orders = new DataSet();
adapter.Fill(orders, "Order");
Console.WriteLine("Thread {0} returned {1} rows", Thread.CurrentThread.ManagedThreadId, orders.Tables[0].Rows.Count);
}
TCPView结果如下所示，这是我期望在连接池解决方案中看到的，即 TCP连接被重用
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61316 dev-database01 ms-sql-s ESTABLISHED 1 88 776 2,684,495 43,800 16
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61317 dev-database01 ms-sql-s ESTABLISHED 1 88 507 1,998,709 6,326 1
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61318 dev-database01 ms-sql-s ESTABLISHED 2 176 862 3,081,722 49,640 19
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61319 dev-database01 ms-sql-s ESTABLISHED 2 176 952 3,128,657 14,600 9
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61320 dev-database01 ms-sql-s ESTABLISHED 2 176 1,149 3,569,440 25,747 8
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61321 dev-database01 ms-sql-s ESTABLISHED 2 176 1,166 3,788,974
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61322 dev-database01 ms-sql-s ESTABLISHED 2 176 884 3,197,392 8,713 2
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61323 dev-database01 ms-sql-s ESTABLISHED 2 176 535 1,816,150
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61324 dev-database01 ms-sql-s ESTABLISHED 2 176 631 2,197,973
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61327 dev-database01 ms-sql-s ESTABLISHED 2 176 1,037 3,344,226 18,980 5
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61328 dev-database01 ms-sql-s ESTABLISHED 3 264 1,271 4,057,097 30,660 13
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61331 dev-database01 ms-sql-s ESTABLISHED 2 176 780 2,639,988 8,760 2
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61333 dev-database01 ms-sql-s ESTABLISHED 2 176 1,041 3,352,777 31,248 12
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61334 dev-database01 ms-sql-s ESTABLISHED 6 995 729 2,387,668
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61335 dev-database01 ms-sql-s ESTABLISHED 6 995 601 1,917,537 23,937 6
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61336 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61339 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61340 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61342 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61343 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61344 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61345 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61346 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61356 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61357 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61358 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61359 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61362 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61363 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61364 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61365 dev-database01 ms-sql-s ESTABLISHED
DatabaseTcpPortTester.vshost.exe 5036 TCP localhost 61369 dev-database01 ms-sql-s ESTABLISHED
[System Process] 0 TCP localhost 61395 dev-database01 epmap TIME_WAIT
答案 0 :(得分：2)
在netstat输出中，所有这些都处于TIME_WAIT状态，指示实际关闭之前TCP套接字的状态。这并不意味着数据库连接处于活动状态，只是TCP正处于套接字关闭的过程中。
其中有多少人处于ESTABLISHED州？这将告诉您在该时间点打开的数据库连接的确切数量。
您可以参考以下链接了解不同的TCP套接字状态。 https://en.wikipedia.org/wiki/Transmission_Control_Protocol
答案 1 :(得分：0)
Hibernate配置正确，您应该使用C3P0。如果您为每个请求创建SessionFactory，那么您可以看到比最大池大小更多的连接的唯一方法。
从你的配置中，我看到DAO被创建为原型，这是不寻常的，因为它们应该是单身。确保LocalSessionFactoryBean也不使用原型范围。
答案 2 :(得分：0)
问题是当使用DriverManagerDataSource并且通过在LocalSessionFactoryBean
所以我切换到ComboPooledDataSource并使用此处提供的setter方法设置c3p0属性，而不是LocalSessionFactoryBean，因此您最终会得到以下结果：
@Bean(name="dataSource")
public DataSource dataSource() throws PropertyVetoException {
Properties hibernateProperties = new Properties();
hibernateProperties.put("hibernate.dialect", "org.hibernate.dialect.MySQL5InnoDBDialect");
hibernateProperties.put("hibernate.show_sql", false);
hibernateProperties.put("hibernate.generate_statistics", false);
hibernateProperties.put("hibernate.hbm2ddl.auto", "update");
hibernateProperties.put("hibernate.use_sql_comments", false);
//note the "hibernate.c3p0...." properties are no longer in use
ComboPooledDataSource dataSource = new ComboPooledDataSource();
dataSource.setDriverClass(jobDatabaseProperties.getJobDatabaseDriverClassName());
dataSource.setJdbcUrl(jobDatabaseProperties.getJobDatabaseUrl());
dataSource.setUser(jobDatabaseProperties.getJobDatabaseUsername());
dataSource.setPassword(jobDatabaseProperties.getJobDatabasePassword());
dataSource.setAcquireIncrement(1);
dataSource.setMinPoolSize(5);
dataSource.setMaxPoolSize(100);
dataSource.setMaxIdleTime(20);
return new dataSource;
}
我现在可以看到c3p0在日志中被初始化，并且池中按照预期控制了连接数。
在http://syntx.io/configuring-c3p0-connection-pooling-with-spring-and-hibernate/
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