Re: memory leak

That's not fair, you can't say "the behavior is not as simple as either of
us originally thought" and not tell me. :) Just kidding. Seriously
though, I'd love to find out more about this issue because everything we've
seen, it seems like the VM doesn't garbage collect before throwing an OOM on
..NET 1.1 and CF. On a scale of 1 to 10, that's pretty serious. Again, I'm
hoping I'm wrong and it is something simple.

Anything to add here or blog?

Thanks,

Hilton


"<ctacke/>" <ctacke[@]opennetcf[dot]com> wrote in message
news:%23K$Iel%23vGHA.1436@xxxxxxxxxxxxxxxxxxxxxxx
Just FYI I'm running some tests on this and talking with the CF team about
what I'm seeing - the behavior is not as simple as either of us originally
thought. Once I have some definitive info I'll blog it.


--
Chris Tacke
OpenNETCF Consulting
www.opennetcf.com
--



"Hilton" <nospam@xxxxxxxxxx> wrote in message
news:Xa_Dg.6860$1f6.2623@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I find it interesting that the exceptions are different too (desktop
versus CF).

Ilya or anyone else from MSFT want to jump in here???

Hilton


"<ctacke/>" <ctacke_AT_OpenNETCF_com> wrote in message
news:%23Rq%23Sw5vGHA.3392@xxxxxxxxxxxxxxxxxxxxxxx
Sounds like an OOM on a bitmap allocation isn't triggering a GC like it
should. If that's the case, it's certainly a bug.

-Chris


"Hilton" <nospam@xxxxxxxxxx> wrote in message
news:gOTDg.688$q63.333@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Chris,

I did some more testing. Using CF 2.0 makes no difference - still
throws exception. Adding GC.Collect() causes the memory to drop, app
keeps running both on desktop and PPC. So, the OOM is not causing a
GC.Collect() because that would cause the OOM condition to go away, the
"new" to then succeed etc. Looks like they fixed this on the desktop
in a later version of the .NET Framework according to Doug's post. I'm
still running 1.1.4322.2032.

Chris, do you agree? (given that my findings stated above are correct)

Hilton


"<ctacke/>" <ctacke_AT_OpenNETCF_com> wrote in message
news:edV$yhzvGHA.4688@xxxxxxxxxxxxxxxxxxxxxxx
I don't have Studio on this machine. What happens if you put a
GC.Collect in the exception handler, then allow it to continue?

-Chris




"Hilton" <nospam@xxxxxxxxxx> wrote in message
news:f9PDg.9744$FN2.6734@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Chris,

I agree there is a misunderstanding of the fundamentals. Run the
short program below and see for yourself. On the Pocket PC, the
device runs out of memory and throws an OutOfmemoryException; one the
desktop, it used all 2GB that was free when it started and threw a
"System.ArgumentException: Invalid parameter used" on the "new
Bitmap" line.

Now do you still agree that the GC will cleanup Bitmap objects?
Sorry Chirs, it doesn't happen as you say cause the "new Bitmap" code
below that *does not keep a reference to each bitmap* ran out of
memory.

Hilton
----------------------------
Create a form, add a timer with the code:
this.timer = new Timer ();
this.timer.Interval = 250;
this.timer.Tick += new EventHandler(timer_Tick);
this.timer.Enabled = true;

then add this method:

private void timer_Tick(object sender, EventArgs ea)
{
bool error = false;

this.timer.Enabled = false;

try
{
this.bmp = new Bitmap (1024, 1024);

this.Text = DateTime.Now.ToLongTimeString();
}
catch (Exception e)
{
error = true;

using (System.IO.StreamWriter sw = new
System.IO.StreamWriter ("exp.txt"))
{
sw.WriteLine (e.ToString());
}

this.Text = "Exception";
}
this.timer.Enabled = !error;
}
---------------

"<ctacke/>" <ctacke[@]opennetcf[dot]com> wrote in message
news:esCAJeyvGHA.1772@xxxxxxxxxxxxxxxxxxxxxxx
I think there's still a misundestanding of the fundamentals.

Dispose is not a required call - it is optional. Your application
knows better than anything else when you are done with resources,
and at that point, you can call Dispose to let the GC know that you
are done with those resources. These classes are written so that
during that call, managed resources are released.

If you don't call Dispose, that's fine. When the GC goes to
collect, it will walk the roots. It will see that the Bitmap has no
references, and it will then run Dispose on it for you and move it
to the Finalizer queue. On the _next_ GC cycle, the actual Bitmap
will be released. This all happens automatically, without your
intervention. It just happens late - when the GC is collecting -
likely because you're low on resources.

Calling Dispose is simply a good idea because it allows the release
of system resources when the app is done with them rather than
waiting for the system to GC.

For more info, take a look at my presentation from MEDC:
http://blog.opennetcf.org/ctacke/PermaLink,guid,e806d34b-a8d8-45e8-9de8-bec58818fafe.aspx


--
Chris Tacke
OpenNETCF Consulting
www.opennetcf.com
--




"Hilton" <nospam@xxxxxxxxxx> wrote in message
news:0lMDg.8207$9T3.540@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Chris,

This has come up before, so no use beating a dead horse (I'm the
guilty one here since I first mentioned it), but here are some
points which hopefully helps to explain my comments:

1. If ALL objects were required to be disposed, would that be a
design bug? Of course it would, it is .NET with a garbage
collector.
2. Then why do we have to dispose Bitmap? Because MS took a
short-cut. Note that MS have already said that they will *fix* this
problem.
3. Another bad choice IMHO was to put Bitmap in System.Drawing -
that is the wrong place since you don't only draw with Bitmap and a
Bitmap image should not be directly associated with UI. It should
be in System.Image or something similar. Here is an example in
pseudo-C#: Imagine you wanted to convert all BMP files to PNG files
using a command line EXE. It should simply be "using System.Image;
foreach BMPFile in directory { new Bitmap (BMPFile).SaveAs
(PNG); }" but instead we have to include System.Drawing (UI stuff),
plus we need to do our own memory management (the code above would
have a huge memory leak).
4. FWIW: I think Dispose should be an optional call, not a
mandatory call required to prevent a memory leak.
5. There are other things like why they called it SortedList
instead of SortedMap etc... (unrelated to Bitmap)

Bottom line, I love C#, work with it day in and day out, absolutely
darn amazing on Pocket PCs etc, so don't think for a second I'm
bashing the C# language, the .NET team, or Microsoft. Just
sometimes, bad design decisions get made (*IHMO*).

Hilton


"<ctacke/>" <ctacke[@]opennetcf[dot]com> wrote in message
news:eWyovzwvGHA.3372@xxxxxxxxxxxxxxxxxxxxxxx
The same has to be done on the full framework, and again, it's not
a bug.

-Chris


"Hilton" <nospam@xxxxxxxxxx> wrote in message
news:gvJDg.12218$gY6.3863@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I bet you're doing something like "xyz.Image = new Bitmap (...)" -
right? If so, there is a bug in the CF design/implementation
(IMHO) that forces you to do your own memory management; i.e. for
every "new Bitmap ()" you do, you'll need to do a "Dispose()" on
that bitmap when you're done with it (aka malloc and free).

Let us know if that helps,

Hilton


"raju" <ponnurajs@xxxxxxxxx> wrote in message
news:1155390117.643466.283160@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hai

In my device application (windows ce application using
vb.net), i
am having nearly 25 forms. Moving from one form to another form,
just i
am hide the first form and show the second form.

Each form I am having some picturebox, putting images for
that
picturebox using imagelist.

My application works very well. But, if the application
running
contineously for 1 or 2 hours, i am getting error such as "low
memory".


when i checked the memory, it will automatically increasing
when
the application is in running. First initial time, it occupies
22 mb
and it increasing upto 32 to 35 mb.

What is the reason for this? and how to correct this memory
problem.

Regards
Raju.























.

Relevant Pages

  • Re: memory leak
    ... explicit GC and it worked just as it should - memory climbed up to near 2GB ... Now do you still agree that the GC will cleanup Bitmap objects? ... Dispose is not a required call - it is optional. ... those resources. ...
    (microsoft.public.dotnet.framework.compactframework)
  • Re: memory leak
    ... I am pretty diligent when it comes to disposing unmanaged resources. ... If an OOM occurs when attempting to create a bitmap from a binary ... making it appear that the device has more available memory. ... Dispose is not a required call - it is optional. ...
    (microsoft.public.dotnet.framework.compactframework)
  • Re: memory leak
    ... Adding GC.Collectcauses the memory to drop, ... Now do you still agree that the GC will cleanup Bitmap objects? ... Dispose is not a required call - it is optional. ... those resources. ...
    (microsoft.public.dotnet.framework.compactframework)
  • Re: memory leak
    ... explicit GC and it worked just as it should - memory climbed up to near ... Now do you still agree that the GC will cleanup Bitmap objects? ... Dispose is not a required call - it is optional. ... those resources. ...
    (microsoft.public.dotnet.framework.compactframework)
  • Re: memory leak
    ... explicit GC and it worked just as it should - memory climbed up to near ... Now do you still agree that the GC will cleanup Bitmap objects? ... Dispose is not a required call - it is optional. ... done with those resources. ...
    (microsoft.public.dotnet.framework.compactframework)