Apache dbcp 连接池无法正常工作

Question

我正在尝试使用mysql连接池连接到数据库apache dbcp2按照此处的教程进行操作：

https://git-wip-us.apache.org/repos/asf?p=commons-dbcp.git;a=blob;f=doc/PoolingDataSourceExample.java;h=2a12c74898930b9623223db1597b8a8052a6f1df;hb=HEAD

返回连接的数据库连接类如下所示：

public class DbConnection {
private static interface Singleton {
    final DbConnection INSTANCE = new DbConnection();
}
private final PoolingDataSource<PoolableConnection> dataSource;
private DbConnection() {
    // A ConnectionFactory that the pool will use to create Connections.
    DriverManagerConnectionFactory connectionFactory = new DriverManagerConnectionFactory(url, user, pass);  //url,user,pass for db connnection
    //implement the pooling functionality.
    PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory, null);
    GenericObjectPoolConfig config = new GenericObjectPoolConfig();
    config.setMaxWaitMillis(500);
    config.setMaxTotal(20);
    config.setMaxIdle(5);
    config.setMinIdle(5);
    //PoolingDataSource expect an ObjectPool
    ObjectPool<PoolableConnection> connectionPool = new GenericObjectPool<>(poolableConnectionFactory, config);
    // Set the poolableConnectionFactory's pool property to the owning pool
    poolableConnectionFactory.setPool(connectionPool);
    this.dataSource = new PoolingDataSource<>(connectionPool);
}
public static Connection getCon() throws SQLException {
    return Singleton.INSTANCE.dataSource.getConnection();
}
} 

我正在使用 apache jmeter 来测试连接并从我的 mysql 数据库中返回一些东西。我创建了 100 个用户，爬坡周期(以秒为单位(为 2 秒。我创建了一个Http request，当我尝试在view results tree中查看我的响应时，我成功获得了前 20 个请求的响应。从 (21 到 100( 的后续请求具有空白响应。我经历了许多问题，涉及：

java.sql.SQLException：无法获取连接，池错误超时 等待空闲对象

我以以下方式访问我的代码：

try (PreparedStatement ps = DbConnection.getCon().prepareStatement("SELECT id FROM test WHERE id =?;")) {
        ps.setString(1, id);
        try (
                ResultSet rs = ps.executeQuery()) {
            return rs.next();
        }
    } catch (Exception ex) {
    }

Answer 1

您没有关闭Connection对象，您必须在 try-with-resources 块中声明这样的变量：

try (Connection conn = DbConnection.getCon(); 
       PreparedStatement ps = conn.prepareStatement("SELECT id FROM test WHERE id =?;")) {

您还需要关闭ResultSet，要么在方法中调用close方法ResultSet，要么使用返回它的新方法将其添加到 try-with-resources 块中