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Simple problem: Why does this cause a massive memory leak?I have a huge memory leak problem in what is really very simple data insert code. In my app I'm trying to use a typed dataset to insert into a database. It adds quite a few rows (say hundreds). Unfortunately it has a big ass memory leak and I dont understand why. The code below demonstrates the memory leak. It's like nothing is cleaned up after PerformOperation is called. According to .net memory profiler, after running the console app, there are huge numbers of undisposed objects and meory usage is through the roof. I've tried to attach a screenshot from .net memory profiler showing what I mean Any help would be very much appreciated Thanks Simon class Program { static void Main(string[] args) { for (int i = 0; i < 1000; i++) { PerformOperation(); } } private static void PerformOperation() { GPSPositionTableAdapter da = new GPSPositionTableAdapter(); GPSPositionTable tblGPSPositions = new GPSPositionTable(); GPSPositionRow currentRow = null; for (int i = 0; i < 50; i++) { currentRow = tblGPSPositions.NewGPSPositionRow(); currentRow.DownloadID = 1; currentRow.TTUReference = 9999; currentRow.Timestamp = DateTime.Now; currentRow.Latitude = 66.66666666666; currentRow.Longitude = 66.66666666666; tblGPSPositions.AddGPSPositionRow(currentRow); } da.Update(tblGPSPositions); } } Simon,
I am curious, why do you think there should be disposed objects? The GC is not deterministic, and you cant say by looking at a program "I should have disposed objects here". The only place you can even begin to make that sort of assumption is where you have an explicit call to the static Collect method on the GC class, which you do not have here. What is it that you are looking to do? -- - Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com Show quote "Simon" <si***@nothanks.com> wrote in message news:uqw3NTOaHHA.3996@TK2MSFTNGP03.phx.gbl... > Hi all, > > I have a huge memory leak problem in what is really very simple data > insert code. > > In my app I'm trying to use a typed dataset to insert into a database. It > adds quite a few rows (say hundreds). Unfortunately it has a big ass > memory leak and I dont understand why. > > The code below demonstrates the memory leak. It's like nothing is cleaned > up after PerformOperation is called. > > According to .net memory profiler, after running the console app, there > are huge numbers of undisposed objects and meory usage is through the > roof. > > I've tried to attach a screenshot from .net memory profiler showing what I > mean > > Any help would be very much appreciated > > Thanks > > Simon > > class Program { > > static void Main(string[] args) { > for (int i = 0; i < 1000; i++) { > PerformOperation(); > } > } > > private static void PerformOperation() { > GPSPositionTableAdapter da = new GPSPositionTableAdapter(); > GPSPositionTable tblGPSPositions = new GPSPositionTable(); > GPSPositionRow currentRow = null; > > for (int i = 0; i < 50; i++) { > > currentRow = tblGPSPositions.NewGPSPositionRow(); > > currentRow.DownloadID = 1; > currentRow.TTUReference = 9999; > currentRow.Timestamp = DateTime.Now; > currentRow.Latitude = 66.66666666666; > currentRow.Longitude = 66.66666666666; > > tblGPSPositions.AddGPSPositionRow(currentRow); > } > > da.Update(tblGPSPositions); > } > > } > According to .net memory profiler, after running the console app, there If you want objects to be disposed, as opposed to finalized during > are huge numbers of undisposed objects and meory usage is through the > roof. collection, you must call IDisposable.Dispose on each object. The using clause is a convenient way to do this in most cases. simon,
See inline > private static void PerformOperation() { This is te place where the old tblGSSPostitions should be given to the GC as > GPSPositionTableAdapter da = new GPSPositionTableAdapter(); > GPSPositionTable tblGPSPositions = new GPSPositionTable(); long as there are no rows anymore to it attached by instance by the currentRow which is added to the tblGPSPpostitions. Maybe will a simple clear before the new help in this. Cor Show quote > GPSPositionRow currentRow = null; > > for (int i = 0; i < 50; i++) { > > currentRow = tblGPSPositions.NewGPSPositionRow(); > > currentRow.DownloadID = 1; > currentRow.TTUReference = 9999; > currentRow.Timestamp = DateTime.Now; > currentRow.Latitude = 66.66666666666; > currentRow.Longitude = 66.66666666666; > > tblGPSPositions.AddGPSPositionRow(currentRow); > } > > da.Update(tblGPSPositions); > } > > } Hi Guys,
Thanks for your thoughts on this. The reason why its troubling me is that this application runs non-stop. Over a period of say, 24hrs, the memory usage of the application balloons to over 400 meg. If I leave it long enough, it will eventually throw an exception due to running out of memory. Even if it wasn't throwing a memory exception - why hasn't the garbage collector kicked in much sooner? Either way, I need to get it to stop using so much memory, and all the undisposed instances in memory profiler seemed to be the culprit. Is this behaviour normal? Can you tell me what to do? Sincerest Thanks Simon Simon,
Did you do what I wrote? Cor Show quote "Simon" <si***@nothanks.com> schreef in bericht news:Ov1diGVaHHA.3996@TK2MSFTNGP03.phx.gbl... > Hi Guys, > > Thanks for your thoughts on this. > > The reason why its troubling me is that this application runs non-stop. > Over a period of say, 24hrs, the memory usage of the application balloons > to over 400 meg. If I leave it long enough, it will eventually throw an > exception due to running out of memory. Even if it wasn't throwing a > memory exception - why hasn't the garbage collector kicked in much sooner? > > Either way, I need to get it to stop using so much memory, and all the > undisposed instances in memory profiler seemed to be the culprit. > > Is this behaviour normal? Can you tell me what to do? > > Sincerest Thanks > > Simon Hi Cor,
Thanks for your reply. I havent had a chance to try what you're suggesting as the code is on another machine, but I can't see why it would work... PerformOperation is called say, 100 times and each time the datatable and data adapter et al should go completely out of scope and therefore be fair game for the GC. If I call Clear on the data table just after it's create as you suggest, I'd be calling clear on a completely new instance with nothing in it... Am I perhaps misunderstanding something? Many thanks Simon Simon,
I mean before it is created. GPSPositionTableAdapter da = new GPSPositionTableAdapter(); tblGSPositions.Clear(); 'At least the table which will be replaces loses now his rows, and I hope its references. 'Be aware that not the same table is used again, only the references is replaced by another one with 'your sentence bellow. If there are references to the existing those will stay as long as the program lives. GPSPositionTable tblGPSPositions = new GPSPositionTable(); Cor Show quote "Simon" <si***@nothanks.com> schreef in bericht news:eR1yskVaHHA.208@TK2MSFTNGP05.phx.gbl... > Hi Cor, > > Thanks for your reply. I havent had a chance to try what you're suggesting > as the code is on another machine, but I can't see why it would work... > > PerformOperation is called say, 100 times and each time the datatable and > data adapter et al should go completely out of scope and therefore be fair > game for the GC. > > If I call Clear on the data table just after it's create as you suggest, > I'd be calling clear on a completely new instance with nothing in it... > > Am I perhaps misunderstanding something? > > Many thanks > > Simon Cor,
There are two issues with your solution: 1. It won't compile as you are accessing a variable before its declaration 2. It doesn't matter whether you invoke Clear or not as reference goes out of the scope anyway. -- Miha Markic [MVP C#, INETA Country Leader for Slovenia] RightHand .NET consulting & development www.rthand.com Blog: http://cs.rthand.com/blogs/blog_with_righthand/ Show quote "Cor Ligthert [MVP]" <notmyfirstn***@planet.nl> wrote in message news:uENB05aaHHA.4692@TK2MSFTNGP04.phx.gbl... > Simon, > > I mean before it is created. > > GPSPositionTableAdapter da = new GPSPositionTableAdapter(); > tblGSPositions.Clear(); > 'At least the table which will be replaces loses now his rows, and I hope > its references. > 'Be aware that not the same table is used again, only the references is > replaced by another one with > 'your sentence bellow. If there are references to the existing those will > stay as long as the program lives. > GPSPositionTable tblGPSPositions = new GPSPositionTable(); > > Cor > > "Simon" <si***@nothanks.com> schreef in bericht > news:eR1yskVaHHA.208@TK2MSFTNGP05.phx.gbl... >> Hi Cor, >> >> Thanks for your reply. I havent had a chance to try what you're >> suggesting as the code is on another machine, but I can't see why it >> would work... >> >> PerformOperation is called say, 100 times and each time the datatable and >> data adapter et al should go completely out of scope and therefore be >> fair game for the GC. >> >> If I call Clear on the data table just after it's create as you suggest, >> I'd be calling clear on a completely new instance with nothing in it... >> >> Am I perhaps misunderstanding something? >> >> Many thanks >> >> Simon > > Miha Markic [MVP C#] wrote:
> Cor, Yeah - I've got to agree with that assesment I'm afraid. Unless I'm > > There are two issues with your solution: > 1. It won't compile as you are accessing a variable before its declaration > 2. It doesn't matter whether you invoke Clear or not as reference goes > out of the scope anyway. > being particularly thick, the code as suggested wouldnt even compile - // Won't compile tblGSPositions.Clear(); GPSPositionTable tblGPSPositions = new GPSPositionTable(); Thanks Simon Miha,
I agree with you that I missed the declaration part and this one won't go, however the idea was that often the problem is that the old object stays, because although it goes out of scope, holds or has references to it. Maybe will this go with the declaration global. I trying this with the shortes code I can think about. cor Show quote > Cor, > > There are two issues with your solution: > 1. It won't compile as you are accessing a variable before its declaration > 2. It doesn't matter whether you invoke Clear or not as reference goes out > of the scope anyway. > > -- > Miha Markic [MVP C#, INETA Country Leader for Slovenia] > RightHand .NET consulting & development www.rthand.com > Blog: http://cs.rthand.com/blogs/blog_with_righthand/ > > "Cor Ligthert [MVP]" <notmyfirstn***@planet.nl> wrote in message > news:uENB05aaHHA.4692@TK2MSFTNGP04.phx.gbl... >> Simon, >> >> I mean before it is created. >> >> GPSPositionTableAdapter da = new GPSPositionTableAdapter(); >> tblGSPositions.Clear(); >> 'At least the table which will be replaces loses now his rows, and I hope >> its references. >> 'Be aware that not the same table is used again, only the references is >> replaced by another one with >> 'your sentence bellow. If there are references to the existing those will >> stay as long as the program lives. >> GPSPositionTable tblGPSPositions = new GPSPositionTable(); >> >> Cor >> >> "Simon" <si***@nothanks.com> schreef in bericht >> news:eR1yskVaHHA.208@TK2MSFTNGP05.phx.gbl... >>> Hi Cor, >>> >>> Thanks for your reply. I havent had a chance to try what you're >>> suggesting as the code is on another machine, but I can't see why it >>> would work... >>> >>> PerformOperation is called say, 100 times and each time the datatable >>> and data adapter et al should go completely out of scope and therefore >>> be fair game for the GC. >>> >>> If I call Clear on the data table just after it's create as you suggest, >>> I'd be calling clear on a completely new instance with nothing in it... >>> >>> Am I perhaps misunderstanding something? >>> >>> Many thanks >>> >>> Simon >> >> > "Cor Ligthert [MVP]" <notmyfirstn***@planet.nl> wrote in message If something is holding the reference (lets say parent) to instance you want news:OdZj2BlaHHA.5108@TK2MSFTNGP03.phx.gbl... > Miha, > > I agree with you that I missed the declaration part and this one won't go, > however the idea was that often the problem is that the old object stays, > because although it goes out of scope, holds or has references to it. get rid of then you have to make sure to either a) drop that reference b) make sure every reference to parent is dropped so the graph isn't referenced from outside. Either way Clear would not help. -- Miha Markic [MVP C#, INETA Country Leader for Slovenia] RightHand .NET consulting & development www.rthand.com Blog: http://cs.rthand.com/blogs/blog_with_righthand/ Cor Ligthert [MVP] wrote:
Show quote > simon, Hi Cor,> > See inline >> private static void PerformOperation() { >> GPSPositionTableAdapter da = new GPSPositionTableAdapter(); >> GPSPositionTable tblGPSPositions = new GPSPositionTable(); > > This is te place where the old tblGSSPostitions should be given to the GC as > long as there are no rows anymore to it attached by instance by the > currentRow which is added to the tblGPSPpostitions. > > Maybe will a simple clear before the new help in this. > > Cor > > >> GPSPositionRow currentRow = null; >> >> for (int i = 0; i < 50; i++) { >> >> currentRow = tblGPSPositions.NewGPSPositionRow(); >> >> currentRow.DownloadID = 1; >> currentRow.TTUReference = 9999; >> currentRow.Timestamp = DateTime.Now; >> currentRow.Latitude = 66.66666666666; >> currentRow.Longitude = 66.66666666666; >> >> tblGPSPositions.AddGPSPositionRow(currentRow); >> } >> >> da.Update(tblGPSPositions); >> } >> >> } > > As I understand it, tblGPSPositions should be made available to the garbage collector as soon as PerformOperation goes out of scope, not when GPSPositionTable tblGPSPositions = new GPSPositionTable(); is called. Is this not the case? Thanks Simon You should look for live (not disposed) instances - those are causing
problems. Anyway, what live instances are there? -- Miha Markic [MVP C#, INETA Country Leader for Slovenia] RightHand .NET consulting & development www.rthand.com Blog: http://cs.rthand.com/blogs/blog_with_righthand/ Show quote "Simon" <si***@nothanks.com> wrote in message news:uqw3NTOaHHA.3996@TK2MSFTNGP03.phx.gbl... > Hi all, > > I have a huge memory leak problem in what is really very simple data > insert code. > > In my app I'm trying to use a typed dataset to insert into a database. It > adds quite a few rows (say hundreds). Unfortunately it has a big ass > memory leak and I dont understand why. > > The code below demonstrates the memory leak. It's like nothing is cleaned > up after PerformOperation is called. > > According to .net memory profiler, after running the console app, there > are huge numbers of undisposed objects and meory usage is through the > roof. > > I've tried to attach a screenshot from .net memory profiler showing what I > mean Smion, how do you say there is a memory leak?.. Did you see the windows task
manager or use a memory profiler tool ??? VJ Show quote "Simon" <si***@nothanks.com> wrote in message news:uqw3NTOaHHA.3996@TK2MSFTNGP03.phx.gbl... > Hi all, > > I have a huge memory leak problem in what is really very simple data > insert code. > > In my app I'm trying to use a typed dataset to insert into a database. It > adds quite a few rows (say hundreds). Unfortunately it has a big ass > memory leak and I dont understand why. > > The code below demonstrates the memory leak. It's like nothing is cleaned > up after PerformOperation is called. > > According to .net memory profiler, after running the console app, there > are huge numbers of undisposed objects and meory usage is through the > roof. > > I've tried to attach a screenshot from .net memory profiler showing what I > mean > > Any help would be very much appreciated > > Thanks > > Simon > > class Program { > > static void Main(string[] args) { > for (int i = 0; i < 1000; i++) { > PerformOperation(); > } > } > > private static void PerformOperation() { > GPSPositionTableAdapter da = new GPSPositionTableAdapter(); > GPSPositionTable tblGPSPositions = new GPSPositionTable(); > GPSPositionRow currentRow = null; > > for (int i = 0; i < 50; i++) { > > currentRow = tblGPSPositions.NewGPSPositionRow(); > > currentRow.DownloadID = 1; > currentRow.TTUReference = 9999; > currentRow.Timestamp = DateTime.Now; > currentRow.Latitude = 66.66666666666; > currentRow.Longitude = 66.66666666666; > > tblGPSPositions.AddGPSPositionRow(currentRow); > } > > da.Update(tblGPSPositions); > } > > } Hi Everyone,
I have a small confession to make - I was misunderstanding the readings I was getting from the memory profiler. There is a memory leak, but it isn't in the code that I posted. That code on its own doesnt cause a memory leak. I do still have a problem though that I don't know how to fix. It the code I posted earlier, I ommitted (for clarity) the fact that I actually download stuff using a COM component before adding it to the database. It is this unmanaged code that is the source of the memory leak. Can anyone give me any general advice on how to ensure that these COM objects are cleaned up as I loop through each COM object? Sorry for the confusion. You've all been very helpful though so thank you everyone. You convinced me that the managed code shouldnt be the source of the problem and made me look again at the unmanaged issue - an area that I thought I had eliminated from my enquiries. Sorry and thanks again Simon Implement IDisposable on COM objects and explicitly release unmaged
resources in this. And when using the com object instance, always call dispose() when done.The link or example with MSDN IDisposible documentation should help you get started. if you have questions ask. VJ Show quote "Simon" <si***@nothanks.com> wrote in message news:OvHWWlXaHHA.3584@TK2MSFTNGP02.phx.gbl... > Hi Everyone, > > I have a small confession to make - I was misunderstanding the readings I > was getting from the memory profiler. There is a memory leak, but it isn't > in the code that I posted. That code on its own doesnt cause a memory > leak. > > I do still have a problem though that I don't know how to fix. It the code > I posted earlier, I ommitted (for clarity) the fact that I actually > download stuff using a COM component before adding it to the database. > > It is this unmanaged code that is the source of the memory leak. Can > anyone give me any general advice on how to ensure that these COM objects > are cleaned up as I loop through each COM object? > > Sorry for the confusion. You've all been very helpful though so thank you > everyone. You convinced me that the managed code shouldnt be the source of > the problem and made me look again at the unmanaged issue - an area that I > thought I had eliminated from my enquiries. > > Sorry and thanks again > > Simon Hi VJ
Thanks for your reply. I'm not sure how to "implement IDisposable" on these objects as they don't have any such method. The COM objects are part of a third party programming API that I have no control over. How do I get rid of them if they dont have a Dispose() method or any obvious equivelant? Thanks again Simon "Simon" <si***@nothanks.com> wrote in message Yeah, that's nonsense. If the COM component really has a memory leak, you news:OcNlsUYaHHA.2076@TK2MSFTNGP04.phx.gbl... > Hi VJ > > Thanks for your reply. > > I'm not sure how to "implement IDisposable" on these objects as they don't > have any such method. The COM objects are part of a third party > programming API that I have no control over. > > How do I get rid of them if they dont have a Dispose() method or any > obvious equivelant? > would need to fix it in the COM component. However, often .NET code using COM components have poor memory performance because the Runtime Callable Wrappers that .NET uses to wrap the COM interface pointers will not destroy the COM component until they are finalized. This can cause lots of memory problems, although it's not technically a leak. As a best practice, anytime you are using a COM component from .NET, explicitly call System.Runtime.InteropServices.Marshal.ReleaseComObject when you are done with the COM component. This will immediately decrement the reference count on the COM component and should clean up any unmanaged memory associated with the component. David Hi Guys,
Thanks for your help so far. I have a couple of questions I'm hoping someone could help me with. 1. If I have a method that creates and uses some COM objects, will the resources that those COM objects were using be fair game for release as soon as they go out of scope? Or do I have to do something to get rid of them? 2. Dave mentioned calling System.Runtime.InteropServices.Marshal.ReleaseComObject. I had found a reference to this when googling, but discounted it because the official documentation said that it should only be used for testing purposes. Something about the behaviour being undefined under certain operating conditions. Should I use this? Surely there must be a well known way of getting rid of COM gubbins once I'm done with it. It sure isn't happening automatically though.... Thanks all Simon Simon one more thing. If your COM object has methods to clean up itself
those have to be called. Just saying, I am sure you are already doing this. See my recent post, this is where IDisposible is used which .NET and the GC call after object is released, so you can do all cleaning. VJ Show quote "Simon" <si***@nothanks.com> wrote in message news:e9lQDhZaHHA.348@TK2MSFTNGP02.phx.gbl... > Hi Guys, > > Thanks for your help so far. > > I have a couple of questions I'm hoping someone could help me with. > > 1. If I have a method that creates and uses some COM objects, will the > resources that those COM objects were using be fair game for release as > soon as they go out of scope? Or do I have to do something to get rid of > them? > > 2. Dave mentioned calling > System.Runtime.InteropServices.Marshal.ReleaseComObject. I had found a > reference to this when googling, but discounted it because the official > documentation said that it should only be used for testing purposes. > Something about the behaviour being undefined under certain operating > conditions. Should I use this? > > Surely there must be a well known way of getting rid of COM gubbins once > I'm done with it. It sure isn't happening automatically though.... > > Thanks all > > Simon "Simon" <si***@nothanks.com> wrote in message Yes, they might get cleaned up any time after the COM object goes out of news:e9lQDhZaHHA.348@TK2MSFTNGP02.phx.gbl... > Hi Guys, > > Thanks for your help so far. > > I have a couple of questions I'm hoping someone could help me with. > > 1. If I have a method that creates and uses some COM objects, will the > resources that those COM objects were using be fair game for release as > soon as they go out of scope? Or do I have to do something to get rid of > them? scope. But normally the Runtime Callable Wrapper must be Garbage-Collected before the COM object can clean itself up. There's no way to tell when that will happen. System.Runtime.InteropServices.Marshal.ReleaseComObject should destroy the COM object immediately. > The official docs say nothing of the kind.> 2. Dave mentioned calling > System.Runtime.InteropServices.Marshal.ReleaseComObject. I had found a > reference to this when googling, but discounted it because the official > documentation said that it should only be used for testing purposes. > Something about the behaviour being undefined under certain operating > conditions. Should I use this? Marshal.ReleaseComObject Method .... This method is used to explicitly control the lifetime of a COM object used from managed code. You should use this method to free the underlying COM object that holds references to resources in a timely manner or when objects must be freed in a specific order. http://msdn2.microsoft.com/en-us/library/system.runtime.interopservices.marshal.releasecomobject.aspx And yes, you should use this method to free the underlying COM object that holds references to resources in a timely manner. David Ok maybe I was not clear on what I said. The IDisposablie if for a .NET
Object not for COM. If the COM has a problem very true you fix it there.., but any time you use Unmanaged code and reference in a .NET app, please wrap it in a object with IDisposiable implementation and make sure you call ..Dispose() after done with the .NET object that has implemented the COM. http://www.microsoft.com/mspress/books/sampchap/5028.aspx Also in addition to what David, said when using Native API Code in .NET make sure they will have permissions to run, see below link what i mean. http://msdn2.microsoft.com/en-us/library/ms182161(VS.80).aspx All this helps you make your .NET app work well with native code, but again if the native code has issues, have to fix it there. VJ Show quote "David Browne" <davidbaxterbrowne no potted m***@hotmail.com> wrote in message news:O%23O%23wRZaHHA.4508@TK2MSFTNGP03.phx.gbl... > > > "Simon" <si***@nothanks.com> wrote in message > news:OcNlsUYaHHA.2076@TK2MSFTNGP04.phx.gbl... >> Hi VJ >> >> Thanks for your reply. >> >> I'm not sure how to "implement IDisposable" on these objects as they >> don't have any such method. The COM objects are part of a third party >> programming API that I have no control over. >> >> How do I get rid of them if they dont have a Dispose() method or any >> obvious equivelant? >> > > Yeah, that's nonsense. If the COM component really has a memory leak, you > would need to fix it in the COM component. > > However, often .NET code using COM components have poor memory performance > because the Runtime Callable Wrappers that .NET uses to wrap the COM > interface pointers will not destroy the COM component until they are > finalized. This can cause lots of memory problems, although it's not > technically a leak. As a best practice, anytime you are using a COM > component from .NET, explicitly call > System.Runtime.InteropServices.Marshal.ReleaseComObject when you are done > with the COM component. This will immediately decrement the reference > count on the COM component and should clean up any unmanaged memory > associated with the component. > > David > >  |
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