dataset

  • Thread starter Thread starter Brad Coble
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B

Brad Coble

What is the best way to handle disposing of a DataSet or DataReader within a
function that returns either? Or should i just trust that its gone when it
goes out of scope?
 
I would be careful about "returning" DataReaders in most instances, as you
can end up tieing up precious resources. With DataSets, it is not as big a
deal, as it does not consume much more than memory.

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Hi Brad,

In .NET world, it's the garbage collector's responsibility to release and
destroy an object. In fact, we have no way to destroy an object manully or
actively in .NET world at all. After an object leaves scope, it is ready
to be destroyed by the garbage collector.

All the DataReaders available in .NET Framework, i.e. SqlDataReader,
OleDataReader, OdbcDataReader and OracleDataReader are derived from the
DbDataReader class. The DbDataReader class has implemented the IDisposable
interface, which means when we don't need to use a DbDataReader object any
more, we should call the IDisposable.Dispose method on the DbDataReader
object to release the resources the object uses immediately.

After calling the Dispose method, we set the DbDataReader object to null or
Nothing to make the object out of scope.

For DataSet, it doesn't implement the IDisposable interface. When we don't
need a DataSet object, just set it to null or Nothing to make it out of
scope.

In your scenario, because you return a DataSet or DataReader in a function,
you couldn't call the Dispose method on the returned DataReader object or
set the DataSet or DataReader to null(Nothing) at the end of the function.
But you should call the Dispose method on the DataReader object and then
set the DataReader or DataSet object to null(Nothing) when you don't need
them outside of the function.

Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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Linda,

Just an addition on this.
In your scenario, because you return a DataSet or DataReader in a
function,
you couldn't call the Dispose method on the returned DataReader object or
set the DataSet or DataReader to null(Nothing) at the end of the function.
But you should call the Dispose method on the DataReader object and then
set the DataReader or DataSet object to null(Nothing) when you don't need
them outside of the function.
Click to expand...

Be aware that the garbage collector has a fine mechanisme to find if an
object is reference is still used.

So you can set the reference to nothing(null) or dispose but that does not
mean that the object will be destructed.

The only thing is then that you cannot reference it anymore.

AFAIK happens the destruction of the object as the Garbage collector by
using 3 kind of procedures has discovered that the object is nowhere in use
anymore.


Cor
 
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