10

运行一段时间后，当我使用至少 20 个浏览器选项卡同时访问 servlet 对我的 servlet 进行压力测试时，出现此错误：

java.sql.SQLException：[tomcat-http--10] 超时：池为空。无法在 10 秒内获取连接，无可用 [size:200; 忙：200；空闲：0；最后等待：10000]。

这是用于此的 XML 配置：

<Resource name="jdbc/MyAppHrd"
          auth="Container"
          type="javax.sql.DataSource"
          factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
          testWhileIdle="true"
          testOnBorrow="true"
          testOnReturn="false"
          validationQuery="SELECT 1"
          validationInterval="30000"
          timeBetweenEvictionRunsMillis="30000"
          maxActive="200"
          minIdle="10"
          maxWait="10000"
          initialSize="200"
          removeAbandonedTimeout="120"
          removeAbandoned="true"
          logAbandoned="false"
          minEvictableIdleTimeMillis="30000"
          jmxEnabled="true"
          jdbcInterceptors="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;
            org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer"
          username="sa"
          password="password"
          driverClassName="net.sourceforge.jtds.jdbc.Driver"
          url="jdbc:jtds:sqlserver://192.168.114.130/MyApp"/>

可能是什么问题呢？

更新：Java代码：

public class MyServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;
    private static final Log LOGGER = LogFactory.getLog(MyServlet.class);

   private void doRequest(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

        CallableStatement stmt = null;
        ResultSet rs = null;

        Connection conn = null;
        try {

            conn = getConnection();

            stmt = conn.prepareCall("{call sp_SomeSPP(?)}");
            stmt.setLong(1, getId());

            rs = stmt.executeQuery();

            // set mime type
            while (rs.next()) {
                if (rs.getInt(1)==someValue()) {
                    doStuff();
                    break;
                }
            }
            stmt = conn.prepareCall("{call sp_SomeSP(?)}");
            stmt.setLong(1, getId());

            rs = stmt.executeQuery();
            if (rs.next()) {
                // do stuff
            }

            RequestDispatcher rd = getServletContext().getRequestDispatcher("/SomeJSP.jsp");
            rd.forward(request, response);
            return;
        } catch (NamingException e) {
            LOGGER.error("Database connection lookup failed", e);
        } catch (SQLException e) {
            LOGGER.error("Query failed", e);
        } catch (IllegalStateException e) {
            LOGGER.error("View failed", e);
        } finally {
            try {
                if (rs!=null && !rs.isClosed()) {
                    rs.close(); 
                }
            } catch (NullPointerException e) {
                LOGGER.error("Result set closing failed", e);
            } catch (SQLException e) {
                LOGGER.error("Result set closing failed", e);
            }
            try {
                if (stmt!=null) stmt.close();
            } catch (NullPointerException e) {
                LOGGER.error("Statement closing failed", e);
            } catch (SQLException e) {
                LOGGER.error("Statement closing failed", e);
            }
            try {
                if (conn != null){
                    conn.close();
                    conn = null;
                }
            } catch (NullPointerException e) {
                LOGGER.error("Database connection closing failed", e);
            } catch (SQLException e) {
                LOGGER.error("Database connection closing failed", e);
            }
        }

   }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doRequest(request, response);
    }

    protected static Connection getConnection() throws NamingException, SQLException {
        InitialContext cxt = new InitialContext();
        String jndiName = "java:/comp/env/jdbc/MyDBHrd";
        ConnectionPoolDataSource dataSource = (ConnectionPoolDataSource) cxt.lookup(jndiName);
        PooledConnection pooledConnection = dataSource.getPooledConnection();
        Connection conn = pooledConnection.getConnection();
        return conn; // Obtain connection from pool
    }
4

6 回答 6

5

我建议您将 getConnection 方法更改为以下内容，您实际上可能会通过直接通过 javax.sql.PooledConnection 接口删除池支持

        InitialContext cxt = new InitialContext();
        String jndiName = "java:/comp/env/jdbc/MyDBHrd";
        DataSource dataSource = (DataSource) cxt.lookup(jndiName);
        return dataSource.getConnection();

还可以使用DBUtils#closeQuietly 之类的东西来清理您的连接

更新：您正在从连接中删除池支持。如果您运行以下命令并查看输出，您将看到直接从 DataSource 检索的连接是包装了 PooledConnection 的 ProxyConnection。

public static void main(String[] args) throws Exception {

    Properties properties = new Properties();
    properties.put("username", "sa");
    properties.put("password", "password");
    properties.put("driverClassName", "net.sourceforge.jtds.jdbc.Driver");
    properties.put("url", "jdbc:jtds:sqlserver://192.168.114.130/MyApp");       

    DataSourceFactory dsFactory = new DataSourceFactory();      
    DataSource ds = dsFactory.createDataSource(properties);     
    ConnectionPoolDataSource cpds = (ConnectionPoolDataSource) ds;
    PooledConnection pooledConnection = cpds.getPooledConnection();

    System.out.println("Pooled Connection - [" + ds.getConnection() + "]"); // Close will return to the Pool
    System.out.println("Internal Connection - [" + pooledConnection.getConnection() + "]"); // Close will just close the connection and not return to pool

}
于 2012-12-20T17:32:32.037 回答
4

可能，您保持连接的时间过长。

确保在开始处理请求时不打开数据库连接，然后在最终提交响应时释放它。

典型的错误是：

    @Override
    protected void doGet (
            final HttpServletRequest request,
            final HttpServletResponse response
        ) throws
            ServletException,
            IOException
    {
        Connection conn = myGetConnection( );

        try
        {
            ...
            // some request handling


        }
        finally
        {
            conn.close( )
        }
    }

在这段代码中，数据库连接的生命周期完全取决于连接到服务器的客户端。

更好的模式是

    @Override
    protected void doGet (
            final HttpServletRequest request,
            final HttpServletResponse response
        ) throws
            ServletException,
            IOException
    {
        // some request preprocessing
        MyProcessedRequest parsedInputFromRequest =
            getInputFromRequest( request );

        final MyModel model;
        {
           // Model generation
           Connection conn = myGetConnection( );

           try
           {
              model = new MyModel( conn, parsedInputFromRequest );
           }
           finally
           {
              conn.close( );
           }
        }


        generateResponse( response, model );         
    }

请注意，如果瓶颈在于模型生成，您仍然会用完连接，但这现在是 DBA 的一个问题，这与数据库端更好的数据管理/索引有关。

于 2012-12-20T16:42:28.140 回答
0

在以下之前关闭您的连接。

RequestDispatcher rd = getServletContext().getRequestDispatcher("/SomeJSP.jsp");
        rd.forward(request, response);
        return;

如果不需要，也删除 return。

于 2012-12-20T16:47:36.180 回答
0

检查您的 jdbc 连接在完成过程后是否关闭。它可能是由未关闭的连接引起的。

于 2012-12-20T16:34:23.160 回答
0

首先，您没有在方法主体内关闭Statement和对象。ResultSet

当您调用时它们应该被清理（根据 JDBC 规范），但在池设置中，它们实际上可能不会被清理。closeConnection

其次，您正在解开池连接并返回将破坏一切的底层连接。

所以，修改你的代码是这样的：

 try {
        conn = getConnection();

        stmt = conn.prepareCall("{call sp_SomeSPP(?)}");
        stmt.setLong(1, getId());

        rs = stmt.executeQuery();

        // set mime type
        while (rs.next()) {
            if (rs.getInt(1)==someValue()) {
                doStuff();
                break;
            }
        }

        // ADD THESE LINES
        rs.close(); rs = null;
        stmt.close(); stmt = null;

        stmt = conn.prepareCall("{call sp_SomeSP(?)}");
        stmt.setLong(1, getId());

        rs = stmt.executeQuery();
        if (rs.next()) {
            // do stuff
        }
}

....

protected static Connection getConnection() throws NamingException, SQLException {
    InitialContext cxt = new InitialContext();
    String jndiName = "java:/comp/env/jdbc/MyDBHrd";
    DataSource dataSource = (DataSource) cxt.lookup(jndiName);
    return dataSource.getPooledConnection();
}

而且，正如其他人所说，您肯定希望在执行诸如转发到另一个页面之类的操作之前清理您的资源。否则，您保持连接的时间会比必要的时间长得多。它是一种关键资源：像对待它一样对待它。

于 2012-12-20T18:53:57.307 回答
0

您当前提供的代码看起来很长/很复杂，但很好。

但是，我猜您的“doStuff”方法可能是泄漏更多连接的候选者

于 2012-12-20T17:13:57.970 回答