garbage collection and calling dll's (eg win32 api)

[Wilfried Mestdagh]

Hi,

I have a few related questios:

1. if I pass a string to win32 api (or other dll not written in .net), is it
possible GC cleans up while function is still busy ? eg:

public class Win32
{
[DllImport("User32.dll")]
public static extern IntPtr FindWindow(string ClassName, string
WindowName);

And call it:

IntPtr Win = Win32.FindWindow(ClassName, null);

2. Does it make a difference if ClassName is a literal inside the exe,
because in that case the string is only a pointer to something in read only
mem, so no memory allocation, eg:

string ClassName = "theclass";
IntPtr Win = Win32.FindWindow(ClassName, null);

3. Is it possible to block the GC for a while, for example if I have time
critical code to execute, I dont want to let GC slow down machine if there is
a lot to clean up ?

--
rgds, Wilfried
http://www.mestdagh.biz

[Mattias Sjögren]

Wilfried,

1. if I pass a string to win32 api (or other dll not written in .net), is it
possible GC cleans up while function is still busy ?
No.

2. Does it make a difference if ClassName is a literal inside the exe,
No

because in that case the string is only a pointer to something in read only
mem, so no memory allocation, eg:
The string is still allocated from the GC heap.

3. Is it possible to block the GC for a while, for example if I have time
critical code to execute,
No.

I dont want to let GC slow down machine if there is
a lot to clean up ?

I wouldn't worry about that unless you've actually measured the time
used by GC and determined that it's a problem.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
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