Unable to read data from the transport connection exception

Question

I've got a MySQL 5.5 DB server, using Entity Framework 4.3, MySQL Connector 6.5.4.

The problem that I'm seeing is that over a slow connection (~192kbs) seems to be fairly consistent.

The scenario is that I first call a method that looks like this:

using (var db = new IceCreamEntities(ConnectionString, null, null, null, "infinite timeout"))
{
   db.desserts.Add(myDessert);
   db.SaveChanges()

   db.dessertData.Add(new dessertBlob() { DessertId = myDessert.Id, Data = someData });
}

and then I call closely after that (say, within 30 seconds or so) a method to get that back. It looks like:

using (var db = new IceCreamEntities(ConnectionString, null, null, null, "infinite timeout"))
{
   var myDessertData = db.dessertData.Where(m => m.DessertId == myId).FirstOrDefault();
   return myDessertData;
}

Now, the IceCreamEntities constructor call there that I'm using does the following:

public IceCreamEntities(string connectionString, string unused2, string unused3, string unused4, string forLongRunningStuff)
: base(connectionString)
{
   var objectContext = (this as IObjectContextAdapter).ObjectContext;
   objectContext.CommandTimeout = 0;
}

(there are a couple other constructors that are used with different timeouts, but that is probably not germane to the discussion)

The blob I'm putting into that dessertData table is about 3 megabytes in size.

When I'm not on a slow connection, I don't see this problem.

The exception I get is:

System.Data.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details.

---> MySql.Data.MySqlClient.MySqlException: Fatal error encountered during command execution.

---> MySql.Data.MySqlClient.MySqlException: Fatal error encountered attempting to read the resultset.

---> MySql.Data.MySqlClient.MySqlException: Reading from the stream has failed.
---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)

--- End of inner exception stack trace ---

at MySql.Data.Common.MyNetworkStream.HandleOrRethrowException(Exception e)

at MySql.Data.Common.MyNetworkStream.Read(Byte[] buffer, Int32 offset, Int32 count)

at MySql.Data.MySqlClient.TimedStream.Read(Byte[] buffer, Int32 offset, Int32 count)

at System.IO.BufferedStream.Read(Byte[] array, Int32 offset, Int32 count)

at MySql.Data.MySqlClient.MySqlStream.ReadFully(Stream stream, Byte[] buffer, Int32 offset, Int32 count)

at MySql.Data.MySqlClient.MySqlStream.LoadPacket()

--- End of inner exception stack trace ---

at MySql.Data.MySqlClient.MySqlStream.LoadPacket()

at MySql.Data.MySqlClient.MySqlStream.ReadPacket()

at MySql.Data.MySqlClient.NativeDriver.FetchDataRow(Int32 statementId, Int32 columns)

at MySql.Data.MySqlClient.Driver.FetchDataRow(Int32 statementId, Int32 columns)

at MySql.Data.MySqlClient.ResultSet.GetNextRow()

at MySql.Data.MySqlClient.ResultSet..ctor(Driver d, Int32 statementId, Int32 numCols)

at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)

at MySql.Data.MySqlClient.MySqlDataReader.NextResult()

--- End of inner exception stack trace ---

at MySql.Data.MySqlClient.MySqlDataReader.NextResult()

at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)

--- End of inner exception stack trace ---

at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)

at MySql.Data.Entity.EFMySqlCommand.ExecuteDbDataReader(CommandBehavior behavior)

at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)

--- End of inner exception stack trace ---

at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)

at System.Data.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues)

at System.Data.Objects.ObjectQuery1.GetResults(Nullable1 forMergeOption)

at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator()

at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)

at System.Data.Entity.Internal.Linq.DbQueryProvider.Execute[TResult](Expression expression)

at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)

at IceCream.Repository.GetDessertData(Int64 dessertId) in ....

One other data point - I can call the method that does the add twice in a row with the same sized blob and I don't get this error (or the equivalent). It only happens when I do an Add and then follow it up with the Retrieve.

Any ideas how to address this? I had thought that settting the command timeout value to 0 would solve my problems but it doesn't.

Edit

One other point is that I did the math and 3 megabytes at 192mbs should take somewhere in the neighborhood of 128 seconds to transfer.

itsmatt itsmatt · Accepted Answer · 2012-09-13T18:03:44

So, after much searching and reading, I adjusted the following values in the my.ini file:

net_read_timeout

net_write_timeout

By setting those to the value 99999 and restarting my db server, I'm able to now retrieve that 3M file over the slow connection without further incident.

Unable to read data from the transport connection exception

1 Answers