Re: Why does this TextOut() sometimes hang up?

From:

"Alexander Grigoriev" <alegr@earthlink.net>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 10 May 2007 20:55:22 -0700

Message-ID:

<uXfn2A4kHHA.4872@TK2MSFTNGP03.phx.gbl>

Typical policy is to:

1) assign "preferable" processor in "round" fashion when a thread is
created. This means you may get slightly better balancing if you create all
CPU-intensive threads at once.
2) schedule a thread next time on the same processor. This time you'll get
less L1 cache misses (and L2, if the're not shared).

"Peter Olcott" <NoSpam@SeeScreen.com> wrote in message
news:GpH0i.138349$mJ1.62347@newsfe22.lga...

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:9qa643hgj4houe8mjp6bid8cq6s4r428je@4ax.com...

Yes, in fact it *does* run the thread on any available processor; this is
the advantage of
muiltithreading.

Note that you get best performance if the number of running threads is no
greater than the
number of available CPUs (take a look at my Thread Affinity Explorer to
see how
performance can actually drop with massive numbers of threads)
joe

Of course if the processor is spending most of its time context switching
it would not be getting much performance on the tasks that it is
switching. I wonder how sophisticated the load balancing would be on XP or
Vista? Would these both be smart enough to place a very CPU intensive
process on its own processor?

On Wed, 9 May 2007 23:22:21 -0500, "Peter Olcott" <NoSpam@SeeScreen.com>
wrote:

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in
message news:jbv443ljs188hnspe0ha1h71cv4gj0mc41@4ax.com...

Any time you put this kind of code in, it is screaming
"this should have been a thread!"
Such gross hacks were required in Win16, but they should
be avoided in Win32.
joe

It just occurred to me that this sort of advice (about
multi-threading) has recently taken on much more
significance with multi-processor machines becoming the
norm. I would estimate that it would be pretty easy for the
OS to allocate a thread to a separate processor, once the
programmer has divided up the processing into separate
threads.

On Wed, 9 May 2007 17:46:18 -0500, "Peter Olcott"
<NoSpam@SeeScreen.com> wrote:

"Mark Salsbery" <MarkSalsbery@discussions.microsoft.com>
wrote in message
news:03D471C4-281F-403A-A60B-A67459BF1AE9@microsoft.com...

I should have read the code more closely :)

Maybe you need to pump messages in the loop if it's on
the
same thread as
the window's UI thread.

//An example message pump. Call periodically in your
loop.
MSG msg;
while ( ::PeekMessage( &msg, NULL, 0, 0, PM_NOREMOVE ) )
{
  if ( !AfxGetApp()->PumpMessage( ) )
  {
     break;
  }
}

I stuck the above code in a function called PumpMessages()
and it solved my problem, thanks!

"Peter Olcott" wrote:

"Mark Salsbery"
<MarkSalsbery@discussions.microsoft.com>
wrote in message
news:E603B544-517C-4595-B222-BD6364F7792A@microsoft.com...

Are you painting over the top of your drawn text?

Besides the TextOut() in the loop you may need to
redraw
the same text in
response to WM_PAINT (OnPaint()) to make sure it's
redrawn
when the window
is repainted as well as in the loop.

Mark

I am using the basic double buffering method that
paints
a
memory DC to the screen.

"Peter Olcott" wrote:

I tried to make the equivalent of a simple
ProgressBar
by
displaying a count in the window of the outermost
one
of
several nested loops. This process is very CPU
intensive
so
I have to force screen updates. The count works
correctly
unless I move the window, and then the window is no
longer
updated. What is causing this, and how can I fix it?

// The TextOut() display code inside a very tight
loop
    ClientArea.TextOut(0, 0, String,
strlen(String));
    MainWin->InvalidateRect(NULL);
    MainWin->UpdateWindow();

// Window member data
  CDC ClientArea; // virtual window device
context
  CBitmap m_bmp; // virtual window bitmap

// Window Constructor
MainWindow::MainWindow()
{
  ScreenWidth = GetSystemMetrics(SM_CXSCREEN);
  ScreenHeight = GetSystemMetrics(SM_CYSCREEN);
  Create(NULL, "SeeScreen the Screen Recognizer",
WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL,
rectDefault,
NULL, "TextMenu");
  CClientDC DC(this);

  // Create bitmap for virtual window
  ClientArea.CreateCompatibleDC(&DC);
  m_bmp.CreateCompatibleBitmap(&DC, ScreenWidth,
ScreenHeight);
  ClientArea.SelectObject(&m_bmp);

  // use standard background
  MainBrush.CreateStockObject(WHITE_BRUSH);
  ClientArea.SelectObject(&MainBrush);

  // paint background of virtual window
  ClientArea.PatBlt(0, 0, ScreenWidth, ScreenHeight,
PATCOPY);
}

// Update screen using contents of virtual window.
afx_msg void MainWindow::OnPaint()
{
  CPaintDC DC(this);
  DC.BitBlt(0, 0, ScreenWidth, ScreenHeight,
&ClientArea,
0,
0, SRCCOPY);
}

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm