AWS RDS的间歇性SQL连接问题

我们当前在ASP.NET网站(基于Sitecore)上遇到间歇性问题，该网站似乎在15分钟的随机时间内无法连接到SQL Server.15分钟后，问题自行解决，网站重新启动.

We are currently experiencing an intermittent issue with our ASP.NET website (built on Sitecore) where the website cannot connect to SQL server for seemingly random periods of 15 minutes. After 15 minutes, the issue resolves itself and the website comes back up.

错误消息是:

Exception: System.Data.SqlClient.SqlException
Message: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
Source: .Net SqlClient Data Provider
   at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling)
   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, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   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 oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Sitecore.Data.DataProviders.Sql.DataProviderCommand..ctor(IDbCommand command, DataProviderTransaction transaction, Boolean openConnection)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<>c__DisplayClass4.<CreateCommand>b__3()
   at Sitecore.Data.DataProviders.NullRetryer.Execute[T](Func`1 action, Action recover)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<>c__DisplayClass12.<CreateReader>b__10()
   at Sitecore.Data.DataProviders.NullRetryer.Execute[T](Func`1 action, Action recover)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.CreateReader(String sql, Object[] parameters)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<CreateObjectReader>d__6`1.MoveNext()
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
   at Sitecore.Eventing.EventQueue.ProcessEvents(Action`2 handler)
   at Sitecore.Eventing.EventProvider.RaiseQueuedEvents()

Nested Exception

Exception: System.ComponentModel.Win32Exception
Message: The network path was not found


6420 16:53:53 ERROR Exception processing remote events from database: web
Exception: System.Data.SqlClient.SqlException
Message: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
Source: .Net SqlClient Data Provider
   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 oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Sitecore.Data.DataProviders.Sql.DataProviderCommand..ctor(IDbCommand command, DataProviderTransaction transaction, Boolean openConnection)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<>c__DisplayClass4.<CreateCommand>b__3()
   at Sitecore.Data.DataProviders.NullRetryer.Execute[T](Func`1 action, Action recover)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<>c__DisplayClass12.<CreateReader>b__10()
   at Sitecore.Data.DataProviders.NullRetryer.Execute[T](Func`1 action, Action recover)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.CreateReader(String sql, Object[] parameters)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<CreateObjectReader>d__6`1.MoveNext()
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
   at Sitecore.Eventing.EventQueue.ProcessEvents(Action`2 handler)
   at Sitecore.Eventing.EventProvider.RaiseQueuedEvents()

Nested Exception

Exception: System.ComponentModel.Win32Exception
Message: The network path was not found

如果连接字符串中有错字，此错误消息似乎与您遇到的错误相同，但该站点在99％的时间内正常运行.

This error message, seems to be the same error you'd get if you had a typo in the connection string, but the site functions fine for 99% of the time.

如果错误消息是超时，我可以想象原因是应用程序造成了过多的负载而SQL无法响应-但是，SQL RDS日志显示没有沉重的负载，并且在一段时间内仅断开了连接15分钟.

If the error message was a timeout, I could imagine the cause being that the application is causing excessive load and SQL cannot respond - however, the SQL RDS logs show no heavy load and just a drop off of connections for a period of 15 minutes.

从应用程序/代码的角度来看，有什么可能导致这种情况的发生?

Is there anything from an application/code perspective that could cause this?

15分钟的时间是否有意义?这是某些事情的线索吗?

Is the period of 15 minutes significant? Is that a clue to something in particular?