我有这两种方法

public DataTable GetData1(int Id)
{
    DataTable dt = new DataTable();

    using (SqlConnection sqlcon = new SqlConnection(database.Connection.ConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand("spGetData1", sqlcon))
        {
            cmd.CommandType = CommandType.StoredProcedure;

            cmd.Parameters.Add(new SqlParameter() { ParameterName = "@id", Value = Id});

            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                da.Fill(dt);
            }
        }
    }

    return dt;
}

public DataTable GetData2(int Id)
{
    DataTable dt = new DataTable();

    using (SqlConnection sqlcon = new SqlConnection(database.Connection.ConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand("spGetData2", sqlcon))
        {
            cmd.CommandType = CommandType.StoredProcedure;

            cmd.Parameters.Add(new SqlParameter() { ParameterName = "@id", Value = Id});

            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                da.Fill(dt);
            }
        }
    }
    return dt;
}

我想立即执行它们并获取数据以供进一步处理。

我试过类似的东西

var task1 = Task.Factory.StartNew(() => database.Data.GetData1(1));
var task2 = Task.Factory.StartNew(() => database.Data.GetData2(2));

var taskList = new List<Task> { task1, task2 };

Task.WaitAll(taskList.ToArray());

但在最后一行它崩溃了

there is one or more errors.`

内部异常是

Object reference not set to an instance of an object.

堆栈跟踪

at System.Threading.Tasks.Task.WaitAll(Task[] tasks, Int32 millisecondsTimeout, CancellationToken cancellationToken)

connectionString 是从System.Data.Entity.DbContext.Database 类中获取的

 public class DatabaseRepository : IDisposable
    {
        DbContext dbContext;

        public DatabaseRepository()
        {
             dbContext = new DbContext("connection string ...");
             Data = new DataRepository(dbContext.Database);

        }
        public DataRepository Data { get; set; }
}

但即使我手动设置连接字符串，错误也是一样的，所以我认为错误不在这里。

   using (SqlConnection sqlcon = new SqlConnection("connection string ..."))
   {
      using (SqlCommand cmd = new SqlCommand("spGetData2", sqlcon))
      {
       ...
      }
   }

我该怎么做？我看到一些示例使用 Async 返回类型，但我不想重复这些方法。

最佳答案

database.Connection.ConnectionString 是静态字符串，否则您无法编译，因为“非静态字段、方法或属性(property)”。

考虑到这一点，它不是未初始化的连接字符串，因为它是静态的...即使您故意将静态字符串初始化为 Null，错误消息也将是:

InnerException = {"The ConnectionString property has not been initialized."}

这是一个重现，不会产生错误除非您的 GetData 方法在空对象中:

namespace database
{
public class Program
{
    static void Main(string[] args)
    {
        //WORKS!!
        var repro = new database.Data();
        var task1 = Task.Factory.StartNew(() => repro.GetData1(3));
        var task2 = Task.Factory.StartNew(() => repro.GetData2(5));
        var taskList = new List<Task> { task1, task2 };
        Task.WaitAll(taskList.ToArray());

        //FAILS WITH ERROR REPORTED!!
        repro = null;
        var task1 = Task.Factory.StartNew(() => repro.GetData1(3));
        var task2 = Task.Factory.StartNew(() => repro.GetData2(5));
        var taskList = new List<Task> { task1, task2 };
        Task.WaitAll(taskList.ToArray());
    }
}

class Data
{
    private string connectionString = "Server=.;Database=CRUD_Sample;Integrated Security=True;Asynchronous Processing = True;";
    public DataTable GetData1(int Id)
    {
        DataTable dt = new DataTable();
        using (SqlConnection sqlcon = new SqlConnection(connectionString))
        {
            using (SqlCommand cmd = new SqlCommand("Get_CustomerbyID", sqlcon))
            {
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.Add(new SqlParameter() { ParameterName = "@id", Value = Id });
                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    da.Fill(dt);
                }
            }
        }
        return dt;
    }

    public DataTable GetData2(int Id)
    {
        DataTable dt = new DataTable();
        using (SqlConnection sqlcon = new SqlConnection(connectionString))
        {
            using (SqlCommand cmd = new SqlCommand("Get_CustomerbyID", sqlcon))
            {
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.Add(new SqlParameter() { ParameterName = "@id", Value = Id });
                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    da.Fill(dt);
                }
            }
        }
        return dt;
    }
}
}

调试

如何找到 NullReferenceException 的来源？除了查看异常本身 - 关键是 NRE 将准确地抛出到它发生的位置，然后将鼠标悬停在代码行上的变量上并查看哪个对象为空。

关于c# - 并行执行存储过程，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42395422/