[Insight-users] ITK Multithreading

[Miller, James V (Research)]

ITK does not have any multithreading readers.  However, you could start a separate thread that would read the data and allow your application to do other things while data is being loaded.  If you wanted to do this, you need to use
the itk::MultiThreader::SpawnThread() method.

The GeodesicActiveContours is already multithreaded.  When you run that algorithm, ITK will internally divide the problem across multiple processors.
This is done automatically.

A large number of ITK filters are multithreaded.  They will spread the 
computation across as many processors as you have.  Not all filters are
threaded, however.  Some of the segmentation algorithms require too much 
global information so they cannot be threaded.  

One way to determine if a filter is multithreaded is to look to see 
whether it provides a GenerateData() or ThreadedGenerateData() method. 
GenerateData() methods are single threaded.  But the GenerateData() may use
a mini-pipeline where the components of the pipeline are multithreaded filters.
So it can be hard to determine whether a given filter is multithreaded or not.
But you can usually tell from a system monitor ("top") how many threads 
a filter is using when a calculation is being performed.

Jim


-----Original Message-----
From: insight-users-bounces at itk.org
[mailto:insight-users-bounces at itk.org]On Behalf Of Arun Kulshreshtha
Sent: Friday, February 25, 2005 2:16 PM
To: 'Insight-users at itk.org'
Subject: [Insight-users] ITK Multithreading


Hi,

Can somebody tell me how to use multithreading in ITK. I have a dicom 
series which i want to load using several threads and write it as a 
dicom volume.  I have used the DicomSeriesReader given with ITK but it 
takes time. Further i need to segment the 3D dicom volume using Geodesic 
Active Contours, so how can i use multithreading to imprive the 
performance of segmentation. I have a system with 4 itenium processors.

An example of a multithreading using ITK will also be helpful , if 
anybody has then please attach that too.

Regards
Arun Kulshreshtha

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