[fdo-users] RE: .net Wrapper quirks

[Clayton Hotson]

Bohne,

Try avoiding compound statements like the one you use to clear and add to the insert command's property values - insert.PropertyValues.Clear() and insert.PropertyValues.Add().  Instead try caching a variable outside the loop which represents the return from PropertyValues - and Dispose() it after the loop exits (the way it is written below, a PropertyValueCollection reference is actually created *twice* for each item in the reader, and never disposed, since PropertyValueCollection is also disposable).

I have seen this behavior you report many, many times, and I believe it is related to the generational nature of the garbage collector in .NET not being able to keep up with allocations made during statements like 'insert.PropertyValues.xxx()', especially in loops, and this is why the exception occurs somewhat randomly but only after a certain amount of data is processed.

Basically, there should be an explicit Dispose() called for every, single IDisposable object you access in FDO - and in loops with large amounts of data this must be taken to the absolute extreme.  The 'using' is useful (as you use) and it can lead to perhaps difficult-to-read code, but you might also consider try-finally blocks for disposal of multiple objects.

As Jackie says, it is not necessary to call Dispose() on objects you wrap in the using statement, as this is done automatically when it exits scope.

Anyway, I hope this helps!

Clayton

On SatJul 24, 2010, at Sat Jul 24, 6:02 PM, Bohne wrote:


Hi Jacky,

thanks for your reply.
I  modified my code but still no luck. Even if I'm adding only one integer
value to my Insertcommand (without reading from source) i'm getting this
Exception ( less than before, but still there) ??


private void writeValues(FDO.IFDOSource source, FDO.IFDOSource target,
Graphics graphics)
       {
           //Open Source Connection, if necessary
           if (source.Connection.ConnectionState !=
OSGeo.FDO.Connections.ConnectionState.ConnectionState_Open)
               source.Connection.Open();
           //Open Target Connection, if necessary
           if (target.Connection.ConnectionState !=
OSGeo.FDO.Connections.ConnectionState.ConnectionState_Open)
               target.Connection.Open();

           //Creating Select Command
           ISelect select =
source.Connection.CreateCommand(OSGeo.FDO.Commands.CommandType.CommandType_Select)
as ISelect;
           //setting featureClassName
           select.SetFeatureClassName(source.getFeatureClassName());

          //Filter source
           if (graphics.Filter.Length > 0)
               select.Filter =
OSGeo.FDO.Filter.Filter.Parse(graphics.Filter);

           //creating InsertCommand
           using (IInsert insert =
target.Connection.CreateCommand(OSGeo.FDO.Commands.CommandType.CommandType_Insert)
as IInsert)
           {
           //setting featureClassName
           insert.SetFeatureClassName(target.getFeatureClassName());

          //Counter
           int counter = 0;

           //create Reader
           using (IFeatureReader sourceReader = select.Execute())
           {


               while (sourceReader.ReadNext())
               {
                   //Clear old insertcommand
                   insert.PropertyValues.Clear();
                   //Adding PropertyValues to InsertCommand
                   bool writeRecord = true;// fillRow( insert, source,
sourceReader, target.MyFeatureClass, graphics, counter);
                   insert.PropertyValues.Add(new PropertyValue("MOVEID",
new Int32Value(counter)));
                   //
                   if (writeRecord)
                   {
                       //Executing InsertCommand
                       using (IFeatureReader insertReader =
insert.Execute())
                       {
                           insertReader.Close();
                       }

                   }

                   counter++;
               }

           }

           }
           source.Connection.Close();
           target.Connection.Close();
       }
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