|
dev
newsgroups
|
|||||||||||||||||||||||
|
|||||||||||||||||||||||
Should Dispose be called on DataTable and DataSet objects?"disonnected" (from the database) classes and support IMDB (In Memory Database). The IDisposable interface implemented in DataTable and DataSet is inherited from the MarshalByValue interface which is there to support visual drag&drop capabilities in Visual Studio. We ran same test and after creating many big DataTable objects and reclaiming the memory with GC.Collect() the DataTables are "disposed" and the memory reclaimed and returned to the OS *REGARDLESS* of if we call DataTable.Dispose or NOT. Microsoft, Do we need to call the Dispose methods for DataTable and DataSet objects and if "Yes" - why? Thank you in advance Chavdar Angelov Dispose is meant to clean up unmanaged resources before the object is
garbage collected. The garbage collector will call Dispose on each object it is about to collect if that object implements the IDispose interface, to give it one last chance to clean itself up. Dispose itself does not force the object to be garbage collected. Big difference. AFAIK, right now, there are no unmanaged resources in those objects that would need to be cleaned up via Dispose. In theory, in future versions of the framework there may be. Show quote "Chavdar" <Chav***@discussions.microsoft.com> wrote in message news:BAF16A7C-2DEF-4E0D-A0EF-79F685E933C3@microsoft.com... > It is my understanding that the DataTable and DataSet objects are > "disonnected" (from the database) classes and support IMDB (In Memory > Database). > > The IDisposable interface implemented in DataTable and DataSet is > inherited > from the MarshalByValue interface which is there to support visual > drag&drop > capabilities in Visual Studio. > > We ran same test and after creating many big DataTable objects and > reclaiming the memory with GC.Collect() the DataTables are "disposed" and > the > memory reclaimed and returned to the OS *REGARDLESS* of if we call > DataTable.Dispose or NOT. > > Microsoft, > > Do we need to call the Dispose methods for DataTable and DataSet objects > and > if "Yes" - why? > > Thank you in advance > > Chavdar Angelov > > You said it in your first statement - "Dispose is meant to clean up unmanaged
resources....." Therefore: 1. Any class implementing IDisposable has unmanaged resources. 2. Any class using any IDisposable classes is responsible for calling the Dispose method on them. If the DataTable and DataSet classes do not have any unmanaged resources in them, why do they implement the IDisposable interface? Is this just bad design from Microsoft or are we missing something here? Thanks Chavdar Show quote "Marina Levit [MVP]" wrote: > Dispose is meant to clean up unmanaged resources before the object is > garbage collected. The garbage collector will call Dispose on each object it > is about to collect if that object implements the IDispose interface, to > give it one last chance to clean itself up. > Dispose itself does not force the object to be garbage collected. > Big difference. > > AFAIK, right now, there are no unmanaged resources in those objects that > would need to be cleaned up via Dispose. In theory, in future versions of > the framework there may be. > > "Chavdar" <Chav***@discussions.microsoft.com> wrote in message > news:BAF16A7C-2DEF-4E0D-A0EF-79F685E933C3@microsoft.com... > > It is my understanding that the DataTable and DataSet objects are > > "disonnected" (from the database) classes and support IMDB (In Memory > > Database). > > > > The IDisposable interface implemented in DataTable and DataSet is > > inherited > > from the MarshalByValue interface which is there to support visual > > drag&drop > > capabilities in Visual Studio. > > > > We ran same test and after creating many big DataTable objects and > > reclaiming the memory with GC.Collect() the DataTables are "disposed" and > > the > > memory reclaimed and returned to the OS *REGARDLESS* of if we call > > DataTable.Dispose or NOT. > > > > Microsoft, > > > > Do we need to call the Dispose methods for DataTable and DataSet objects > > and > > if "Yes" - why? > > > > Thank you in advance > > > > Chavdar Angelov > > > > > > > I think there is a misunderstanding here. First of all, the garbage
collector doesn't call Dispose, it calls Finalize, and it is your responsibility to put a call to Dispose (if you have it) in a class destructor. Then, you may want to implement IDisposable to clean up at any time, not waiting for GC. And this clean up is not necessarily related to unmanaged resources. I've already asked Marina to explain in more detail but did not see a response. Chavdar wrote: Show quote > You said it in your first statement - "Dispose is meant to clean up unmanaged > resources....." > > Therefore: > > 1. Any class implementing IDisposable has unmanaged resources. > 2. Any class using any IDisposable classes is responsible for calling the > Dispose method on them. > > If the DataTable and DataSet classes do not have any unmanaged resources in > them, why do they implement the IDisposable interface? > > Is this just bad design from Microsoft or are we missing something here? > > Thanks > > Chavdar > > > > "Marina Levit [MVP]" wrote: > >> Dispose is meant to clean up unmanaged resources before the object is >> garbage collected. The garbage collector will call Dispose on each object it >> is about to collect if that object implements the IDispose interface, to >> give it one last chance to clean itself up. >> Dispose itself does not force the object to be garbage collected. >> Big difference. >> >> AFAIK, right now, there are no unmanaged resources in those objects that >> would need to be cleaned up via Dispose. In theory, in future versions of >> the framework there may be. >> >> "Chavdar" <Chav***@discussions.microsoft.com> wrote in message >> news:BAF16A7C-2DEF-4E0D-A0EF-79F685E933C3@microsoft.com... >>> It is my understanding that the DataTable and DataSet objects are >>> "disonnected" (from the database) classes and support IMDB (In Memory >>> Database). >>> >>> The IDisposable interface implemented in DataTable and DataSet is >>> inherited >>> from the MarshalByValue interface which is there to support visual >>> drag&drop >>> capabilities in Visual Studio. >>> >>> We ran same test and after creating many big DataTable objects and >>> reclaiming the memory with GC.Collect() the DataTables are "disposed" and >>> the >>> memory reclaimed and returned to the OS *REGARDLESS* of if we call >>> DataTable.Dispose or NOT. >>> >>> Microsoft, >>> >>> Do we need to call the Dispose methods for DataTable and DataSet objects >>> and >>> if "Yes" - why? >>> >>> Thank you in advance >>> >>> Chavdar Angelov >>> >>> >> >> Sericinus.
Simple said. The dispose in most classes is to make it your able to override it and with that to make it you possible to finalize unmanaged resources. The dispose is probably in 80% of the mostly used classes. That does not mean that you *should* use it. (It is in 20% of the actual classes). As Marina wrote, AFAWK the system.data namespace (ADONET) does not contain unmanaged resources. Therefore there is no need to dispose any of those as long as you have not added yourself something special to it. Therefore if you are not sure if you should use the dispose and your class implements the component model and with that Idisposable (by instance every form), than don't use it. Some classes want it. That are by instance the modal dialog form. Pens and attributes like that (more meant for the handles not for the memory), hugh memory eaters as bitmaps. There are by the active persons in this newsgroup, those who dispose every label they use in their programs, just because that the label class has a method dispose. They tell, the dispose is not for noting. My opinion is that you should know by every method why you use it. I hope this helps, Cor Show quote "Sericinus hunter" <serh***@flash.net> schreef in bericht news:Zg61g.25533$NS6.13336@newssvr30.news.prodigy.com... > I think there is a misunderstanding here. First of all, the garbage > collector doesn't call Dispose, it calls Finalize, and it is your > responsibility to put a call to Dispose (if you have it) in a class > destructor. Then, you may want to implement IDisposable to clean up > at any time, not waiting for GC. And this clean up is not necessarily > related to unmanaged resources. > I've already asked Marina to explain in more detail but did not see > a response. > > Chavdar wrote: >> You said it in your first statement - "Dispose is meant to clean up >> unmanaged resources....." Therefore: >> >> 1. Any class implementing IDisposable has unmanaged resources. >> 2. Any class using any IDisposable classes is responsible for calling the >> Dispose method on them. If the DataTable and DataSet classes do not have >> any unmanaged resources in them, why do they implement the IDisposable >> interface? Is this just bad design from Microsoft or are we missing >> something here? >> >> Thanks >> >> Chavdar >> >> >> >> "Marina Levit [MVP]" wrote: >> >>> Dispose is meant to clean up unmanaged resources before the object is >>> garbage collected. The garbage collector will call Dispose on each >>> object it is about to collect if that object implements the IDispose >>> interface, to give it one last chance to clean itself up. >>> Dispose itself does not force the object to be garbage collected. >>> Big difference. >>> >>> AFAIK, right now, there are no unmanaged resources in those objects that >>> would need to be cleaned up via Dispose. In theory, in future versions >>> of the framework there may be. >>> >>> "Chavdar" <Chav***@discussions.microsoft.com> wrote in message >>> news:BAF16A7C-2DEF-4E0D-A0EF-79F685E933C3@microsoft.com... >>>> It is my understanding that the DataTable and DataSet objects are >>>> "disonnected" (from the database) classes and support IMDB (In Memory >>>> Database). >>>> >>>> The IDisposable interface implemented in DataTable and DataSet is >>>> inherited >>>> from the MarshalByValue interface which is there to support visual >>>> drag&drop >>>> capabilities in Visual Studio. >>>> >>>> We ran same test and after creating many big DataTable objects and >>>> reclaiming the memory with GC.Collect() the DataTables are "disposed" >>>> and the >>>> memory reclaimed and returned to the OS *REGARDLESS* of if we call >>>> DataTable.Dispose or NOT. >>>> >>>> Microsoft, >>>> >>>> Do we need to call the Dispose methods for DataTable and DataSet >>>> objects and >>>> if "Yes" - why? >>>> >>>> Thank you in advance >>>> >>>> Chavdar Angelov >>>> >>>> >>> >>> Thank you for your response, Cor.
Yes, I understand that you are not obliged to call Dispose. My point is (maybe wrong though) that GS does not call Dispose, contrary to what Marina said. This means that if you override existing Dispose or implement it new and put some clean up code in there which you want to be executed, then you should add call to Dispose in the destructor. This way you make sure your clean up code will be executed even if you forget to call Dispose by yourself, like with using{}. Once in the destructor, it will then be called during the garbage collection process. Cor Ligthert [MVP] wrote: Show quote > Sericinus. > > Simple said. > > The dispose in most classes is to make it your able to override it and with > that to make it you possible to finalize unmanaged resources. The dispose > is probably in 80% of the mostly used classes. That does not mean that you > *should* use it. (It is in 20% of the actual classes). > > As Marina wrote, AFAWK the system.data namespace (ADONET) does not contain > unmanaged resources. Therefore there is no need to dispose any of those as > long as you have not added yourself something special to it. > > Therefore if you are not sure if you should use the dispose and your class > implements the component model and with that Idisposable (by instance every > form), than don't use it. Some classes want it. That are by instance the > modal dialog form. Pens and attributes like that (more meant for the handles > not for the memory), hugh memory eaters as bitmaps. > > There are by the active persons in this newsgroup, those who dispose every > label they use in their programs, just because that the label class has a > method dispose. > > They tell, the dispose is not for noting. My opinion is that you should know > by every method why you use it. > > I hope this helps, > > Cor > > "Sericinus hunter" <serh***@flash.net> schreef in bericht > news:Zg61g.25533$NS6.13336@newssvr30.news.prodigy.com... >> I think there is a misunderstanding here. First of all, the garbage >> collector doesn't call Dispose, it calls Finalize, and it is your >> responsibility to put a call to Dispose (if you have it) in a class >> destructor. Then, you may want to implement IDisposable to clean up >> at any time, not waiting for GC. And this clean up is not necessarily >> related to unmanaged resources. >> I've already asked Marina to explain in more detail but did not see >> a response. >> >> Chavdar wrote: >>> You said it in your first statement - "Dispose is meant to clean up >>> unmanaged resources....." Therefore: >>> >>> 1. Any class implementing IDisposable has unmanaged resources. >>> 2. Any class using any IDisposable classes is responsible for calling the >>> Dispose method on them. If the DataTable and DataSet classes do not have >>> any unmanaged resources in them, why do they implement the IDisposable >>> interface? Is this just bad design from Microsoft or are we missing >>> something here? >>> >>> Thanks >>> >>> Chavdar >>> >>> >>> >>> "Marina Levit [MVP]" wrote: >>> >>>> Dispose is meant to clean up unmanaged resources before the object is >>>> garbage collected. The garbage collector will call Dispose on each >>>> object it is about to collect if that object implements the IDispose >>>> interface, to give it one last chance to clean itself up. >>>> Dispose itself does not force the object to be garbage collected. >>>> Big difference. >>>> >>>> AFAIK, right now, there are no unmanaged resources in those objects that >>>> would need to be cleaned up via Dispose. In theory, in future versions >>>> of the framework there may be. >>>> >>>> "Chavdar" <Chav***@discussions.microsoft.com> wrote in message >>>> news:BAF16A7C-2DEF-4E0D-A0EF-79F685E933C3@microsoft.com... >>>>> It is my understanding that the DataTable and DataSet objects are >>>>> "disonnected" (from the database) classes and support IMDB (In Memory >>>>> Database). >>>>> >>>>> The IDisposable interface implemented in DataTable and DataSet is >>>>> inherited >>>>> from the MarshalByValue interface which is there to support visual >>>>> drag&drop >>>>> capabilities in Visual Studio. >>>>> >>>>> We ran same test and after creating many big DataTable objects and >>>>> reclaiming the memory with GC.Collect() the DataTables are "disposed" >>>>> and the >>>>> memory reclaimed and returned to the OS *REGARDLESS* of if we call >>>>> DataTable.Dispose or NOT. >>>>> >>>>> Microsoft, >>>>> >>>>> Do we need to call the Dispose methods for DataTable and DataSet >>>>> objects and >>>>> if "Yes" - why? >>>>> >>>>> Thank you in advance >>>>> >>>>> Chavdar Angelov >>>>> >>>>> >>>> > >  |
|||||||||||||||||||||||
Other interesting topics