我正试图通过ADO.Net SqlCommand在一个连接上多次调用异步调用存储过程。
每隔半秒就会在一个计时器上触发调用，有时我会按预期收到结果，有时我收到以下错误：
System.Data.SqlClient.SqlException（0x80131904）：发生严重错误 当前命令。如果有的话，结果应该被丢弃 在System.Data.SqlClient.SqlConnection.OnError（SqlException异常，Boolea n breakConnection）
在System.Data.SqlClient.SqlInternalConnection.OnError（SqlException异常 ，Boolean breakConnection）
在System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning（）
在System.Data.SqlClient.TdsParser.Run（RunBehavior runBehavior，SqlCommand cm） dHandler，SqlDataReader dataStream，BulkCopySimpleResultSet bulkCopyHandler，Tds ParserStateObject stateObj）
在System.Data.SqlClient.SqlDataReader.ConsumeMetaData（）
在System.Data.SqlClient.SqlDataReader.get_MetaData（）
在System.Data.SqlClient.SqlCommand.FinishExecuteReader（SqlDataReader ds，Run 行为runBehavior，String resetOptionsString）
在System.Data.SqlClient.SqlCommand.CompleteAsyncExecuteReader（）
在System.Data.SqlClient.SqlCommand.InternalEndExecuteReader（IAsyncResult asy） ncResult，String endMethod）
在System.Data.SqlClient.SqlCommand.EndExecuteReader（IAsyncResult asyncResult） ）
SQL日志重复显示以下错误：
服务器将断开连接，因为客户端驱动程序在会话处于单用户模式时发送了多个请求。当客户端在会话中仍在运行批处理时发送重置连接的请求时，或者在会话重置连接时客户端发送请求时，会发生此错误。请联系客户端驱动程序供应商。
我的连接字符串有MARS和Async = true设置。我目前正在使用SQL Server 2008 Express，尽管目标客户端将是一个完全成熟的SQL Server实例。
我创建了以下控制台应用程序，它在我的机器上表现出相同的行为，我创建的DummySp只在其调用后立即返回
public class BusinessObject
{
public string Name {get; set;}
public void UpdateData(DataTable dataTable)
{
Console.WriteLine("{0}: new data received.",Name);
}
}
public class Program
{
private const string SpName = "DummySp";
private const string ConnectionsString = @"Data Source=(local)\sqlexpress;Initial Catalog=Test;Integrated Security=SSPI;Connection Timeout=3600";
private static readonly object DbRequestLock = new object();
private static readonly ManualResetEvent DatabaseRequestsComplete = new ManualResetEvent(false);
private static int _databaseRequestsLeft;
private static Timer _timer;
static readonly List<BusinessObject> BusinessObjects = new List<BusinessObject>
{
new BusinessObject{Name = "A"},
new BusinessObject{Name = "B"},
new BusinessObject{Name = "C"},
};
static void Main(string[] args)
{
_timer = new Timer(DoQuery, null, 0, 500);
Console.ReadLine();
_timer.Dispose();
}
private static void DoQuery(object state)
{
try
{
lock (DbRequestLock)
{
DatabaseRequestsComplete.Reset();
_databaseRequestsLeft = BusinessObjects.Count;
var builder = new SqlConnectionStringBuilder(ConnectionsString)
{
AsynchronousProcessing = true,
MultipleActiveResultSets = true
};
using (var connection = new SqlConnection(builder.ConnectionString))
{
connection.Open();
foreach (var businessObject in BusinessObjects)
{
var command = new SqlCommand(SpName, connection) { CommandType = CommandType.StoredProcedure };
command.BeginExecuteReader(Callback, new Tuple<SqlCommand, BusinessObject>(command, businessObject));
}
// need to wait for all to complete before closing the connection
DatabaseRequestsComplete.WaitOne(10000);
connection.Close();
}
}
}
catch (Exception ex)
{
Console.WriteLine("Following error occurred while attempting to update objects: " + ex);
}
}
private static void Callback(IAsyncResult result)
{
try
{
var tuple = (Tuple<SqlCommand, BusinessObject>)result.AsyncState;
var businessObject = tuple.Item2;
using (SqlCommand command = tuple.Item1)
{
using (SqlDataReader reader = command.EndExecuteReader(result))
{
using (var table = new DataTable(businessObject.Name))
{
table.Load(reader);
businessObject.UpdateData(table);
}
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
finally
{
// decrement the number of database requests remaining and, if there are 0 fire the mre
if (Interlocked.Decrement(ref _databaseRequestsLeft) == 0)
{
DatabaseRequestsComplete.Set();
}
}
}
}
关于如何克服这个问题的任何想法？
由于
答案 0 :(得分：1)
这不是直接回答我的问题，所以我没有标记它，但我认为值得展示每个对象有一个连接的替代方案，因为这似乎可以绕过这个问题......
private static void DoQuery(object state)
{
try
{
lock (DbRequestLock)
{
var builder = new SqlConnectionStringBuilder(ConnectionsString)
{
AsynchronousProcessing = true,
};
DatabaseRequestsComplete.Reset();
_databaseRequestsLeft = BusinessObjects.Count;
foreach (var businessObject in BusinessObjects)
{
var newConnection = new SqlConnection(builder.ConnectionString);
newConnection.Open();
var command = new SqlCommand(SpName, newConnection) { CommandType = CommandType.StoredProcedure };
command.BeginExecuteReader(Callback, new Tuple<SqlCommand, BusinessObject>(command, businessObject),CommandBehavior.CloseConnection);
}
// need to wait for all to complete DatabaseRequestsComplete.WaitOne(10000);
}
}
catch (Exception ex)
{
Console.WriteLine("Following error occurred while attempting to update objects: " + ex);
}
}
private static void Callback(IAsyncResult result)
{
var tuple = (Tuple<SqlCommand, BusinessObject>)result.AsyncState;
var businessObject = tuple.Item2;
SqlCommand command = tuple.Item1;
try
{
using (SqlDataReader reader = command.EndExecuteReader(result))
{
using (var table = new DataTable(businessObject.Name))
{
table.Load(reader);
businessObject.UpdateData(table);
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
finally
{
// decrement the number of database requests remaining and, if there are 0 fire the mre
if (Interlocked.Decrement(ref _databaseRequestsLeft) == 0)
{
DatabaseRequestsComplete.Set();
}
try
{
command.Dispose();
command.Connection.Dispose();
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
}