Max number of open windows?

[maurizio.ceravolo]

Hi,
I have a new notebook with Vista. When I work I use to open many
windows from explorer, Internet Explorer, Development tools,
documentation and going on. On my new notebook, I noticed that I can't
open endlessly windows. After 30 or 40 windows it stops to launch new
programs. I have 2 gbytes of ram, and never reach the limit of memory.
Is there a method to know which is this limit and is there a way to
improve it?
Thanks

 

[Andrew McLaren]

documentation and going on. On my new notebook, I noticed that I can't
open endlessly windows. After 30 or 40 windows it stops to launch new
programs. I have 2 gbytes of ram, and never reach the limit of memory.
Is there a method to know which is this limit and is there a way to
improve it?

Hi Maurizio

GDI and DWM both support an enormous number of windows, theoretically - for
GDI it is something ridiculous, like 64K windows open.

However, resource pools on the system will become depleted, long before you
hit this limit. The Desktop Heap is a one such resource, which often is the
first to be exhausted. At 30 or 40 windows, it does sound like you are
running out of desktop heap. Sometimes you get an error message; but often,
you find you just can't open any more windows.

Tony Schreiner has stpes to increase the size of your desktop heap, here:
http://blogs.msdn.com/tonyschr/archive/2005/05/25/desktop-heap-limitations.aspx

A more detailed explanation of what desktop heap is, and how it works, is
here:
http://blogs.msdn.com/ntdebugging/archive/2007/01/04/desktop-heap-overview.aspx

There is a utility from Microsoft you can use to monitor Desktop Heap usage.
However it only works on W2K, XP and Server 2003; it doesn't work on Vista
(yet). But might be interesting if you want to explore desktop heap on any
XP machines you have:
http://www.microsoft.com/downloads/...74-97aa-4510-b4b9-b2dc98c8ed8b&displaylang=en

Increasing the size of your desktop heap will let you open more windows.
Note that this will also use a bit more memory. And you may find you run out
again, around 70 or so Windows. But, 70 Windows is quite a lot , enough
for most common uses.

Hope it helps,

 

[Paul Randall]

Hi Maurizio

GDI and DWM both support an enormous number of windows, theoretically -
for GDI it is something ridiculous, like 64K windows open.

However, resource pools on the system will become depleted, long before
you hit this limit. The Desktop Heap is a one such resource, which often
is the first to be exhausted. At 30 or 40 windows, it does sound like you
are running out of desktop heap. Sometimes you get an error message; but
often, you find you just can't open any more windows.

Tony Schreiner has stpes to increase the size of your desktop heap, here:

http://blogs.msdn.com/tonyschr/archive/2005/05/25/desktop-heap-limitations.aspx

A more detailed explanation of what desktop heap is, and how it works, is
here:

http://blogs.msdn.com/ntdebugging/archive/2007/01/04/desktop-heap-overview.aspx

There is a utility from Microsoft you can use to monitor Desktop Heap
usage. However it only works on W2K, XP and Server 2003; it doesn't work
on Vista (yet). But might be interesting if you want to explore desktop
heap on any XP machines you have:

http://www.microsoft.com/downloads/...74-97aa-4510-b4b9-b2dc98c8ed8b&displaylang=en

Increasing the size of your desktop heap will let you open more windows.
Note that this will also use a bit more memory. And you may find you run
out again, around 70 or so Windows. But, 70 Windows is quite a lot ,
enough for most common uses.

Hi, Andrew

The download page for the desktop heap monitor contains the non-useful
statement:
You need the correct version of the Win32k.sys symbol file via Microsoft
symbol server, or at local disk for installation. The following link would
be much more helpful. A copy and paste of the Method 1 command took care of
the symbol problem for me.

http://support.microsoft.com/kb/914216

-Paul Randall

 

[Andrew McLaren]

The download page for the desktop heap monitor contains the non-useful
statement:
You need the correct version of the Win32k.sys symbol file via Microsoft
symbol server, or at local disk for installation.

Hi Paul!

Well gee, I have _NT_SYMBOL_PATH defined on *all* my machines ... doesn't
everybody?

But yes, if you go spelunking into low-level, anatomical details of the OS,
it won't always be a very user-friendly exercise. Mind you (or "mon Dieu",
as the French say) having a public symbol server on the Internet is a HUGE
improvement in user-friendliness, compared to how it used to be. Once upon a
time, we used to wait for CD-ROMs of debug symbols to arrive in the mail ...

And speaking as one who regularly debugs Windows, Solaris, and IBM software:
the Microsoft tools are generally far easier to use, than any other major
vendor. But of course, they could always be better.

The following link would be much more helpful. A copy and paste of the
Method 1 command took care of the symbol problem for me.
http://support.microsoft.com/kb/914216

If you're not using debug symbols on a regular basis, that's probably the
best option.

Regards,

 

[maurizio.ceravolo]

Hi Andrew,
really really thanks!!!! I could not find any documentation about
this. You told me all I need it to know.
Very very interesting.
Thanks a lot