[vtk-developers] Multithreading with Win32 threads

[David Partyka]

I definitely agree but this looks like it should be given
a deprecation cycle as it involves removing API, there are set/get macros
and VTK_MAX_THREAD is a const in a global header. Though, nearly all of the
usage of VTK_MAX_THREAD is in vtkMultiThreader and it definitely would not
be hard to switch it to dynamically store threads.

That said, I can check in a much larger value for VTK_MAX_THREAD right now.
How about 128? 256? 1024? INT_MAX?

After that, myself or someone else can switch it to use a vector instead of
a fixed size array and then add the deprecation macros so people know it's
going away. Does this sound reasonable? Or too cautious? :-p

On Tue, Jan 25, 2011 at 8:04 AM, Will Schroeder
<will.schroeder at kitware.com>wrote:

> I agree with Ken, IMO we should remove hardcoded limits on threads. In fact
> I can see creating some specialized code to determine the "optimal" number
> of threads (with provisions for manual override). After all in the Nat'l Lab
> world that Ken/Sandia resides in, I've heard the dudes talk about hundreds
> or thousands of processes, etc....it's evolving fast and we don't want to
> have to keep changing this.
>
> W
>
>
>
> On Mon, Jan 24, 2011 at 11:14 AM, Moreland, Kenneth <kmorel at sandia.gov>wrote:
>
>>  Why is there a hardcoded maximum in the first place?  It seems to me
>> that whatever number you choose now will be excessively high and/or obsolete
>> in the coming years as the number of cores per processor grows.
>>
>> -Ken
>>
>>
>>
>> On 1/24/11 8:04 AM, "Bill Lorensen" <bill.lorensen at gmail.com> wrote:
>>
>> ITK has had the max set to 128 for quite a while.
>>
>> On Mon, Jan 24, 2011 at 9:53 AM, David Partyka
>> <david.partyka at kitware.com> wrote:
>> > Sure thing, especially considering one can get a machine with dual
>> > Hexa-cores + Hyper Threading resulting in 24 available cores.
>> >
>> > On Mon, Jan 24, 2011 at 9:39 AM, David Cole <david.cole at kitware.com>
>> wrote:
>> >>
>> >> I think it's just old and leftover, and nobody has yet found a
>> compelling
>> >> need for more than 8 threads on Windows. It should be fine to increase
>> this
>> >> number, especially if you actually have a Windows box with more than 8
>> >> processors on it.
>> >>
>> >> Feel free to change your build locally to increase that value. Perhaps
>> >> somebody here on the VTK developers list is also contemplating more
>> powerful
>> >> Window machines these days... Anybody here want to bump this up and
>> commit
>> >> the change?
>> >>
>> >>
>> >> On Mon, Jan 24, 2011 at 5:11 AM, Pavel Pokutnev
>> >> <pavel.pokutnev at googlemail.com> wrote:
>> >>>
>> >>> Hello vtk-devs,
>> >>>
>> >>> sorry, but I would like to repeat my question.
>> >>> There is a define VTK_MAX_THREADS in "Common/vtkSystemIncludes.h". It
>> >>> is defined to 8 for Win32 threads, but for all other platforms to 32.
>> >>> What is the cause for this non-conformity?
>> >>>
>> >>> Best regards,
>> >>> Pavel
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>>
>>    ****      Kenneth Moreland
>>     ***      Sandia National Laboratories
>> ***********
>> *** *** ***  email: kmorel at sandia.gov
>> **  ***  **  phone: (505) 844-8919
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>
> --
> William J. Schroeder, PhD
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