图片的提示就是“超时时间已到,但是尚未从池中获取连接。出现这种情况可能是因为所有池连接均在使用，并且达到了最大池大小”

知道是某个数据没关闭，可是我在很多地方加了close还是不行 有些地方加了会提示检测到无法访问代码，鼠标移到ExecuteReader会提示System.InvalidOperationException System.Data.SqlClient.SqlException异常的信息。

代码：

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public class dataOperate
{
    public  SqlConnection con;
    public dataOperate()
    {
    }
    public  bool execSQL(string sql)
    {
        SqlConnection con = createCon();
        con.Open();
        SqlCommand com = new SqlCommand(sql, con);
        try
        {
            com.ExecuteNonQuery();
            con.Close();
        }
        catch (Exception e)
        {
            con.Close();
            return false;
        }
        return true;
    }
    public  int seleSQL(string sql)
    {
        SqlConnection con = createCon();
        con.Open();
        SqlCommand com = new SqlCommand(sql, con);
        try
        {
          return Convert.ToInt32(com.ExecuteScalar());
        }
        catch (Exception e)
        {
            CloseDB();
            return 0;
        }
    }
    public  DataSet getDataset(string sql, string table)
    {
        using (SqlConnection con = createCon())
        {
            con.Open();
            DataSet ds;
            SqlDataAdapter sda = new SqlDataAdapter(sql, con);
            ds = new DataSet();
            sda.Fill(ds, table);
            return ds;
        }
 
    }
      public SqlDataReader ExceRead(string sql)
    {
        SqlConnection con = createCon();
        con.Open();
        SqlCommand com = new SqlCommand(sql, con);
        SqlDataReader read = com.ExecuteReader();
        return read;
    }
       public  SqlConnection createCon()
    {
        con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConStr"].ToString()); 
             return con;
    }
    public void CloseDB()
    {
        if (con.State == ConnectionState.Open)
        {
            con.Close();
        }
    }
}

我在web.configl里加了个

<connectionStrings>
      <add name="ConStr" connectionString="server=.;database=wz;uid=sa;pwd=;" />
 </connectionStrings>

如果在这里加个Max Pool Size=512 这样治标不治本而且会损坏系统性能  请问有什么好的方法吗