Sql server 不断地接受；“超时时间已过”；来自SQL Azure的会话状态提供程序（实体框架）

我始终从ASP.NET 4.5 Windows Azure Web角色中的会话状态模块接收到一个错误，该模块指向SQL Azure数据库。会话状态模块正在使用dbcontext。 包括stacktrace在内的例外情况是：

System.Data.EntityException: The underlying provider failed on Open. ---> System.Data.SqlClient.SqlException: Connection Timeout Expired.  The timeout period elapsed while attempting to consume the pre-login handshake acknowledgement.  This could be because the pre-login handshake failed or the server was unable to respond back in time.  The duration spent while attempting to connect to this server was - [Pre-Login] initialization=2; handshake=14993;  ---> System.ComponentModel.Win32Exception: The wait operation timed out
--- End of inner exception stack trace ---
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)
at System.Data.SqlClient.TdsParserStateObject.ReadSniSyncOverAsync()
at System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket()
at System.Data.SqlClient.TdsParser.ConsumePreLoginHandshake(Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean& marsCapable)
at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover)
at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)
at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)
at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)
at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions)
at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.Open()
at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure)
--- End of inner exception stack trace ---
at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure)
at System.Data.EntityClient.EntityConnection.Open()
at System.Data.Objects.ObjectContext.EnsureConnection()
at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator()
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source)
at System.Data.Entity.Internal.Linq.InternalSet`1.FindInStore(WrappedEntityKey key, String keyValuesParamName)
at System.Data.Entity.Internal.Linq.InternalSet`1.Find(Object[] keyValues)
at System.Web.Providers.DefaultSessionStateProvider.<>c__DisplayClass14.<SetAndReleaseItemExclusive>b__13()
at Microsoft.Practices.TransientFaultHandling.RetryPolicy.<>c__DisplayClass1.<ExecuteAction>b__0()
at Microsoft.Practices.TransientFaultHandling.RetryPolicy.ExecuteAction[TResult](Func`1 func)
at System.Web.SessionState.SessionStateModule.OnReleaseState(Object source, EventArgs eventArgs)
at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

System.Data.EntityException:基础提供程序在打开时失败。-->System.Data.SqlClient.SqlException:连接超时已过期。尝试使用登录前握手确认时超时。这可能是因为登录前握手失败或服务器无法及时响应。尝试连接到此服务器时所用的持续时间为-[Pre-Login]initialization=2；握手=14993；-->System.ComponentModel.Win32异常：等待操作超时
---内部异常堆栈跟踪的结束---
位于System.Data.SqlClient.SqlInternalConnection.OneError（SqlException异常，布尔断开连接，操作'1 wrapCloseInAction）
位于System.Data.SqlClient.TdsParser.ThroweException和Warning（TdsParserStateObject StateObjectStateObj、布尔调用方连接锁、布尔异步关闭）
位于System.Data.SqlClient.TdsParserStateObject.ReadsInError（TdsParserStateObject stateObj，UInt32错误）
位于System.Data.SqlClient.TdsParserStateObject.ReadsInSyncOverAsync（）处
位于System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket（）处
位于System.Data.SqlClient.TdsParser.ConsumePreLoginHandshake（布尔加密、布尔信任服务器证书、布尔集成安全、布尔和marsCapable）
在System.Data.SqlClient.TdsParser.Connect（ServerInfo ServerInfo、sqlinternalconnectionds connHandler、Boolean ignoresnopentimeout、Int64 timerExpire、Boolean encrypt、Boolean trustServerCert、Boolean integratedSecurity、Boolean with failover）
位于System.Data.SqlClient.SqlInternalConnectionDS.AttemptOneLogin（ServerInfo ServerInfo、String newPassword、SecureString newSecurePassword、Boolean IgnoresInOpenTimeout、TimeoutTimer timeout、Boolean withFailover）
位于System.Data.SqlClient.SqlInternalConnectionDS.LoginOfAliver（ServerInfo服务器信息、字符串newPassword、SecureString newSecurePassword、布尔重定向EducserInstance、SqlConnectionString连接选项、SqlCredential凭证、超时超时）
位于System.Data.SqlClient.SqlInternalConnectionDS.OpenLoginList（超时计时器超时、SqlConnectionString连接选项、SqlCredential凭证、字符串新密码、SecureString NewSecureUserPassword、布尔重定向EduceInstance）
位于System.Data.SqlClient.SqlInternalConnectionDS..ctor（DbConnectionPoolIdentity、SqlConnectionString connectionOptions、SqlCredential凭据、对象providerInfo、String newPassword、SecureString newSecurePassword、Boolean redirectedUserInstance、SqlConnectionString userConnectionOptions）
位于System.Data.SqlClient.SqlConnectionFactory.CreateConnection（DbConnectionOptions、DbConnectionPoolKey、Object poolGroupProviderInfo、DbConnectionPool、DBConnectionOwningConnection、DbConnectionOptions用户选项）
位于System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection（DbConnectionPool池、DbConnectionOptions选项、DbConnectionPoolKey池键、DbConnectionOptions用户选项）
位于System.Data.ProviderBase.DbConnectionPool.CreateObject（DbConnectionOptions用户选项）
位于System.Data.ProviderBase.DbConnectionPool.UserCreateRequest（DbConnectionOptions userOptions）
位于System.Data.ProviderBase.DbConnectionPool.TryGetConnection（DbConnection owningObject、UInt32 waitForMultipleObjectsTimeout、Boolean allowCreate、Boolean OnlyOnEckConnection、DbConnectionOptions userOptions、DbConnectionInternal和connection）
位于System.Data.ProviderBase.DbConnectionPool.TryGetConnection（DbConnection owningObject、TaskCompletionSource`1重试、DbConnectionOptions用户选项、DbConnectionInternal和connection）
位于System.Data.ProviderBase.DbConnectionFactory.TryGetConnection（DbConnection所有者连接、TaskCompletionSource`1重试、DbConnectionOptions用户选项、DbConnectionInternal和connection）
位于System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection（DbConnection outerConnection、DbConnectionFactory connectionFactory、TaskCompletionSource`1重试、DbConnectionOptions用户选项）
位于System.Data.SqlClient.SqlConnection.TryOpen（TaskCompletionSource`1重试）
在System.Data.SqlClient.SqlConnection.Open（）处
位于System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf（布尔openCondition、DbConnection StoreConnectionOpen、DbConnection originalConnection、字符串例外代码、字符串尝试操作、布尔和CloseStoreConnectionUnfailure）
---内部异常堆栈跟踪的结束---
位于System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf（布尔openCondition、DbConnection StoreConnectionOpen、DbConnection originalConnection、字符串例外代码、字符串尝试操作、布尔和CloseStoreConnectionUnfailure）
位于System.Data.EntityClient.EntityConnection.Open（）处
在System.Data.Objects.ObjectContext.EnsureReconnection（）中
位于System.Data.Objects.ObjectQuery`1.GetResults（可为null`1 forMergeOption）
位于System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator（）
在System.Linq.Enumerable.SingleOrDefault[TSource]（IEnumerable`1 source）处
位于System.Linq.Queryable.SingleOrDefault[TSource]（IQueryable`1源）
位于System.Data.Entity.Internal.Linq.InternalSet`1.FindInStore（WrappedEntityKey，String keyValuesParamName）
位于System.Data.Entity.Internal.Linq.InternalSet`1.Find（对象[]keyValues）
在System.Web.Providers.DefaultSessionStateProvider.c__DisplayClass14.b__u13（）中
在Microsoft.Practices.TransientFaultHandling.RetryPolicy.c__DisplayClass1.b__0（）上
在Microsoft.Practices.TransientFaultHandling.RetryPolicy.ExecuteAction[TResult]（Func`1 Func）
位于System.Web.SessionState.SessionStateModule.OnReleaseState（对象源，EventArgs EventArgs）
在System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecut