I've discovered that the exported values for the various THREAD_PRIORITY_ disagree with the values my C acquaintance gave me. The values exported by Win32::Process are : 
THREAD_PRIORITY_HIGHEST         -1
THREAD_PRIORITY_ABOVE_NORMAL    null
THREAD_PRIORITY_NORMAL          -2
THREAD_PRIORITY_BELOW_NORMAL    1
THREAD_PRIORITY_IDLE            2147483647
THREAD_PRIORITY_LOWEST          -15

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The values my C acquaintance gave me are :- 
Description   Process priority  Thread Priority
Realtime          256              15
High              128               2
Above normal    32768               1
Normal             32               0
Below normal    16384              -1
Idle               64              -2
Lowest            n/a             -15

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I use the following code :- 
$returncode=Win32::Process::Open($obj,$pid,0);
print "\n $returncode \n";
$returncode=$obj->SetPriorityClass(THREAD_PRIORITY_LOWEST);
print "\n $returncode \n";

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It returns code 0 (failure) for HIGHEST and NORMAL, 1 (OK) for BELOW, IDLE, LOWEST, but does not in fact set the Thread Priority. In fact it will only set Process Priority, and only when I give it correct values as detailed above. E.g. 
$returncode=$obj->SetPriorityClass(32);

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sets Process Priority to normal as it should. Conclusion : SetPriority does not seem able to set Thread Priority. Or am I missing something ? How do I tell it that it's a Thread Priority I'm trying to change rather than a Process Priority ? Why would the Pod text describe Thread Priority values if the routine won't use them ?

In reply to Re^4: how to change process & thread priority on Win32 ? by rbutcher
in thread how to change process & thread priority on Win32 ? by rbutcher

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