介绍：文件上传功能，使用wcf提供 服务 ， 数据 库使用EntityFramework4 访问 。 问题现象：在wcf有一个文件块上传方法 /// summary /// 上传文件 /// /summary /// param name="block" 文件块信息 /param /// returns 上传文件的信息状态 /returns public o

介绍：文件上传功能，使用wcf提供服务，数据库使用EntityFramework4访问。

问题现象：在wcf有一个文件块上传方法

///

 /// 上传文件
 ///

 ///文件块信息
 ///上传文件的信息状态
publicoverride FileTransportAck UpLoadFile(FileBlock block)
 {
 lock (lockobj)
 {
 //查找文件是否存在
 tab_FileInfo theFileInfo = m_NetBidEnt.tab_FileInfo
 .Where(o => o.FileID.Equals(block.FileID))
 .FirstOrDefault();
 if (theFileInfo ==null)
 thrownew Exception("文件未初始化，上传失败");
 //返回传输结果
 FileTransportAck result =new FileTransportAck();
 //写入文件块
if (FileSysIO.WriteBlock(theFileInfo, block))
 {
 theFileInfo.UploadedSize += block.Size;
 theFileInfo.FileSize = block.Total;
 theFileInfo.UpdateDate = DateTime.Now;
 m_NetBidEnt.SaveChanges();
 }
 else
 thrownew Exception("写入文件块失败");
 //写入返回值
 result.FileId = theFileInfo.FileID;
 result.Offset = (long)theFileInfo.UploadedSize;
 if (theFileInfo.UploadedSize >= block.Total)
 result.TransportStat = FileTransportStat.Finished;
 else
 result.TransportStat = FileTransportStat.ResumeBreakPoint;
 return result;
 }
 }

此方法会在上传文件时循环调用，基本是每10K传一次，即会调用此访问一次，但很奇怪的问题是如果文件在10M以上时，传输过程中会出现停止。此时查看数据库服务整体就像是锁死了一样，使用ssms也无法连接，报出的异常都是连接超时。

后来在wcf的方法内增加了日志用于记录异常，记录的异常如下:

Exception Message
2011-07-2800:38:26,451 An error occurred while starting a transaction on the provider connection. See the inner exception for details.
StackTrace
2011-07-2800:38:26,467 at System.Data.EntityClient.EntityConnection.BeginDbTransaction(IsolationLevel isolationLevel)
 at System.Data.EntityClient.EntityConnection.BeginTransaction()
 at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
 at System.Data.Objects.ObjectContext.SaveChanges()
 at NetBid.FileServices.Impl.FileSysFileService.UpLoadFile(FileBlock block)
 at NetBid.FileServices.Wcf.FileServiceWCF.UploadFileBlock(FileBlock block, Dictionary`2 parameters)
Inner Exception:
2011-07-2800:38:26,467 Inner Exception:System.Data.SqlClient.SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
 at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
 at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
 at System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)
 at System.Data.SqlClient.TdsParserStateObject.ReadSni(DbAsyncResult asyncResult, TdsParserStateObject stateObj)
 at System.Data.SqlClient.TdsParserStateObject.ReadNetworkPacket()
 at System.Data.SqlClient.TdsParserStateObject.ReadBuffer()
 at System.Data.SqlClient.TdsParserStateObject.ReadByte()
 at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
 at System.Data.SqlClient.TdsParser.TdsExecuteTransactionManagerRequest(Byte[] buffer, TransactionManagerRequestType request, String transactionName, TransactionManagerIsolationLevel isoLevel, Int32 timeout, SqlInternalTransaction transaction, TdsParserStateObject stateObj, Boolean isDelegateControlRequest)
 at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransactionYukon(TransactionRequest transactionRequest, String transactionName, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
 at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransaction(TransactionRequest transactionRequest, String name, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
 at System.Data.SqlClient.SqlInternalConnection.BeginSqlTransaction(IsolationLevel iso, String transactionName)
 at System.Data.SqlClient.SqlInternalConnection.BeginTransaction(IsolationLevel iso)
 at System.Data.SqlClient.SqlConnection.BeginDbTransaction(IsolationLevel isolationLevel)
 at System.Data.Common.DbConnection.BeginTransaction(IsolationLevel isolationLevel)
 at System.Data.EntityClient.EntityConnection.BeginDbTransaction(IsolationLevel isolationLevel)
2011-07-2800:38:26,467=======================================================分割线

异常看上去像是事务问题，但有一个奇怪的现象是：上传过程中一旦出现停止现象后，整个数据库都无法访问，只能将数据库的服务停止并重新启动。