I'm looking for common causes of Access Violation errors under .NET.
Things I have checked so far -
- Call Dispose on all objects implementing IDisposable
- Check for valid arguments in calls to COM objects
- Explicitly remove all manually added event handlers
- DO NOT explicity call GC.Collect/GC.WaitForPendingFinalizers
- Add and Remove memory pressure when dealing with native objects (Bitmap, etc..) (Added)
- Verify all PInvoke calls for valid argument types
- Ensure proper use of IntPtr, SafeHandle and HandleRef
- Threading (Thread Safe, Reentrant functions), proper use of waithandles. (Added)
- Ensure application and DLL's are all targetting the same platform (x86 or x64) (The application and dll's should target the same platform as the COM objects.) (Added)
Any other suggestions?
Edit - Moved crash dump analysis to different question.
Any use of unsafe or unmanaged code can get you that type of exceptions.
AccessViolationException:
An access violation occurs in
unmanaged or unsafe code when the code
attempts to read or write to memory
that has not been allocated, or to
which it does not have access. This
usually occurs because a pointer has a
bad value. Not all reads or writes
through bad pointers lead to access
violations, so an access violation
usually indicates that several reads
or writes have occurred through bad
pointers, and that memory might be
corrupted. Thus, access violations
almost always indicate serious
programming errors. In the .NET
Framework version 2.0, an
AccessViolationException clearly
identifies these serious errors.
In programs consisting entirely of
verifiable managed code, all
references are either valid or null,
and access violations are impossible.
An AccessViolationException occurs
only when verifiable managed code
interacts with unmanaged code or with
unsafe managed code.
Recommended:
GFlags and Application Verifier
Are you generating IL at runtime or using a component which does so? Using unsafe C# code, doing pointer manipulation?
