池空。无法在10秒内获取连接

时间：2012-12-20 16:20:26

标签： java tomcat jdbc

经过一段时间的运行后，当我用至少20个浏览器标签同时访问servlet来测试我的servlet时，我遇到了这个错误：

java.sql.SQLException：[tomcat-http - 10]超时：池为空。无法在10秒内获取连接，无法使用[size：200;忙：200;空闲：0; lastwait：10000]

。

以下是此配置的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？

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
    }

6 个答案:

答案 0 :(得分：5)

我建议您将getConnection方法更改为以下内容，您可能实际上是通过直接通过javax.sql.PooledConnection接口删除Pooling支持

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

还可以使用类似DBUtils#closeQuietly的内容来清理连接

更新：您正在从Connection中删除Pooling支持。如果运行以下命令并查看输出，您将看到直接从DataSource检索的连接是包含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

}

答案 1 :(得分：3)

可能你连接的时间太长了。

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将其释放。

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( )
        }
    }

在此代码中，数据库连接生命周期完全取决于连接到服务器的客户端。

更好的模式将是

    @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，如果瓶颈在模型生成中，您仍然会耗尽连接，但现在这对DBA来说是一个问题，这与数据库端更好的数据管理/索引有关。

答案 2 :(得分：0)

检查完成进程后您的jdbc连接是否已关闭。它可能是由未关闭的连接引起的。

答案 3 :(得分：0)

在以下情况之前关闭您的连接。 

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

如果不需要，也请删除退货。

答案 4 :(得分：0)

您目前提供的代码看起来很长/很复杂，但很好。

但是，我猜你的“doStuff”方法可能是泄漏更多连接的候选者

答案 5 :(得分：0)

首先，您没有关闭方法正文中的Statement和ResultSet个对象。

当你在close上调用Connection时（根据JDBC规范），应清理它们，但是在池化设置中，它们实际上可能不会得到清理。

其次，您正在展开池化连接并返回底层连接，这将破坏所有内容。

因此，将代码修改为：

 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，你肯定想在之前清理你的资源你做的事情，比如转发到另一个页面。否则，保持连接的时间远远超过必要的时间。这是一个关键资源：像对待它一样。

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