[vtk-developers] Memory-mapped files in VTK

[Burlen Loring]

meant to say "no special memory management issues"
and (in case you actually would look at the code) mmap use is here: 
https://github.com/burlen/SC11-100GB-Demo/blob/master/SC11DemoReader.h**
*
*<https://github.com/burlen/SC11-100GB-Demo>**
On 05/16/2014 10:50 AM, Burlen Loring wrote:
> Hi David,
>
> I've used mmap with VTK in C++ for the SC11 100GB network demo.
>
> http://dl.acm.org/citation.cfm?id=2287004
> https://github.com/burlen/SC11-100GB-Demo
>
> This use was very ad-hoc and we wanted the data mapped for the life of 
> the app so there were special memory management issues.
>
> patch(http://review.source.kitware.com/#/c/14072/) would have handled 
> situations such as this through a callback invoked when the data array 
> is finished with the pointer. However, that patch was rejected for 
> being overkill. Instead Berk suggested that I simply use the delete 
> event observer, which will always result in data being released but 
> perhaps not as quickly as with the callback or the method that you 
> proposed(eg nothing happens if the array is resized). This approach 
> has worked well for me. I wonder if using the delete event observer 
> would work well in your case?
>
> Burlen
>
>
> On 05/16/2014 10:21 AM, David Gobbi wrote:
>> Hi All,
>>
>> I've used memory mapped files with VTK in the past, using the python
>> "mmap" object to create the map and then passing the resulting pointer
>> to VTK via the SetVoidArray() method.  For large files (several GB) I've
>> found this to be many times faster than e.g. vtkImageReader2.
>>
>> My question: has anyone used mmap with VTK in C++? Specifically,
>> what I'm interested in doing is adding a new "delete method" to the
>> SetVoidPointer() method in vtkDataArrayTemplate.h: it already has
>> "delete methods" for "malloc" and "new", so the idea is to add another
>> delete method for "mmap" that will call munmap on the pointer.
>>
>>    David
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