How to lower my own priority on Windows?

rovf has asked for the wisdom of the Perl Monks concerning the following question:

I would like to lower the priority of my Perl process on Windows. In Re: Changing Windows Process Priority I found a solution to a very similar problem. From http://sourceware.org/pthreads-win32/manual/PortabilityIssues.html I conclude that I need to set the priority to BELOW_NORMAL_PRIORITY_CLASS, so my solution looks like this:

use Win32::Process;
my $currentProcess;
if (Win32::Process::Open($currentProcess, Win32::Process::GetCurrentPr
+ocessID(), 0)) {
$currentProcess->SetPriorityClass(BELOW_NORMAL_PRIORITY_CLASS);
} else {
  warn "Can not find myself ($^E)\n";
}
[download]

This doesn't compile, however, because BELOW_NORMAL_PRIORITY_CLASS is not defined in Win32::Process (and indeed, the perldocs don't mention this constant).

How can I do this properly?

--
Ronald Fischer <ynnor@mm.st>

Comment on How to lower my own priority on Windows? Select or Download Code

Replies are listed 'Best First'.
Re: How to lower my own priority on Windows? by Anonymous Monk on Oct 05, 2009 at 12:04 UTC
Win32::Process says it is exported by request only, So `use Win32::Process qw[ BELOW_NORMAL_PRIORITY_CLASS ];` [download] or `Win32::Process::BELOW_NORMAL_PRIORITY_CLASS();` [download]	[reply] [d/l] [select]
Re^2: How to lower my own priority on Windows? by rovf (Priest) on Oct 05, 2009 at 12:29 UTC
Win32::Process says it is exported by request only Mine doesn't. From the perldocs: `The following additional constants are exported by request only: STILL_ACTIVE` [download] and indeed, if I try your suggestion, I get `"BELOW_NORMAL_PRIORITY_CLASS" is not exported by the Win32::Process mo +dule` [download] I'm using ActiveState Perl 5.8.8. Maybe this constant was introduce only with the Win32::Process version which came with Perl 5.10? -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]
Re^3: How to lower my own priority on Windows? by Anonymous Monk on Oct 05, 2009 at 13:26 UTC
I'm using ActiveState Perl 5.8.8. Maybe this constant was introduce only with the Win32::Process version which came with Perl 5.10? I don't know, I just install from cpan, though the latest is also available from ppm	[reply]
Re: How to lower my own priority on Windows? by Anonymous Monk on Oct 05, 2009 at 13:20 UTC
`BELOW_NORMAL_PRIORITY_CLASS` and its sister `ABOVE_NORMAL_PRIORITY_CLASS` were introduced at Windows NT 5.0, sorry, Windows 2000. A lot of Win32 code is built for the more generice NT 3.5. From the Win32::Process Changes file (on CPAN): `0.13 Fri Jun 13 2008 ... - Add ABOVE_NORMAL_PRIORITY_CLASS and BELOW_NORMAL_PRIORITY_CLASS constants (not exported by default). ...` [download] So it looks like you need a later version for these constants. I have not tried this, but it is possible you could declare your own: `BELOW_NORMAL_PRIORITY_CLASS 0x00004000 ABOVE_NORMAL_PRIORITY_CLASS 0x00008000` [download]	[reply] [d/l] [select]
Re: How to lower my own priority on Windows? by lostjimmy (Chaplain) on Oct 05, 2009 at 13:23 UTC
`BELOW_NORMAL_PRIORITY_CLASS` is defined in `winbase.h`, so you should just be able to define your own constant. It is defined as follows: `#define BELOW_NORMAL_PRIORITY_CLASS 0x00004000`	[reply] [d/l] [select]