[vdug] Re: Frustrating Access Violation Problem (Possible Memory Overwrite)
- From: "Jason Galea" <jason_j_galea@xxxxxxxxxxx>
- To: <vdug@xxxxxxxxxxxxx>
- Date: Tue, 2 Oct 2001 08:42:47 +1000
All,
I made a mistake with the last link. Actually, the home page for the
buglist is - http://buglist.jrsoftware.org/bugsall.htm. This contains a
link to the index page as well.
Jason.
----- Original Message -----
From: "Karin Rodrigues" <k.rodrigues@xxxxxxxxxx>
To: <vdug@xxxxxxxxxxxxx>
Sent: Friday, September 28, 2001 4:11 PM
Subject: [vdug] Re: Frustrating Access Violation Problem (Possible Memory
Overwrite)
>
> Hi Anthony,
>
> The only times I've ever seen this kind of erratic access violations was
> when there was a try.. finally somewhere that frees an object that hadn't
> been initialised properly. Eg.
>
> try
> ...
> MyObj := TObject.create();
> ...
> finally
> MyObj.Free;
> end;
>
> There could easily be an exception before or during the create, therefore
> the create should be before the try, or MyObj set to nil before the try.
If
> MyObj had been used elsewhere and had been freed (not FreeAndNil) then it
> could still be assigned, but the pointer is invalid. So it will
arbitrarily
> free some other object's memory. I'm sure you know all of this already. Of
> course you can have a similar problem without a try..finally, but it's the
> most common.
>
> Cheers,
> Karin
>
> -----Original Message-----
> From: vdug-bounce@xxxxxxxxxxxxx [mailto:vdug-bounce@xxxxxxxxxxxxx]On
> Behalf Of Anthony_Egerton@xxxxxxxx
> Sent: Thursday, 27 September 2001 18:43
> To: vdug@xxxxxxxxxxxxx
> Subject: [vdug] Frustrating Access Violation Problem (Possible Memory
> Overwrite)
>
>
>
> We've just started using DUnit for automated unit testing. A good and
> noble thing.
> Unfortunately we've found a problem. (Or fortunately depending on your
> philosophy of finding bugs)
> When we run the same tests a certain number of times, and after so many
> executions of the same test we start getting Access Violations.
> The Access Violations don't happen at the same point in the code every
> time.
> We fixed a memory leak and the Access Violations stopped appearing.
> My suspicion is that some memory is being overwritten, and the Access
> Violations occur when we encounter the overwritten memory.
>
> The question is how do we find where this is happening?
> Any suggestions would be appreciated at this point (I'm flat out of
> ideas).
>
> We have tried running it in AQTime memory profiling and MemProof to
> hopefully find the memory overwrites. All we did find was a memory leak.
> (Good to find, but not what we were after!)
>
> Thanks in advance,
> Anthony
>
============================================================================
> ==========
>
> "The information contained in this e-mail message may be confidential
> information, and may also be privileged. If you are not the intended
> recipient, any use, interference with, disclosure or copying of this
> material is unauthorised and prohibited. If you have received this
message
> in error, please notify us by return email and delete the original
message."
>
>
>
Other related posts:
