[ITK-dev] [ITK] Thread Pool patch

Mon Apr 7 09:42:03 EDT 2014

Forgot to copy Brad and others on previous reply.

Umang Brahmakshatriya
Advanced Computing Lab
GE Global Research
1 Research Circle K1-3A37C
Niskayuna, NY 12309

From: Brahmakshatriya, Umang (GE Global Research)
Sent: Monday, April 07, 2014 9:40 AM
To: Miller, James V (GE Global Research)
Subject: RE: [ITK-dev] [ITK] Thread Pool patch

I agree. Should remove the "*2". Sorry about that - I forgot to remove it earlier.

Umang Brahmakshatriya
Advanced Computing Lab
GE Global Research
1 Research Circle K1-3A37C
Niskayuna, NY 12309

From: Miller, James V (GE Global Research)
Sent: Monday, April 07, 2014 9:39 AM
To: Brahmakshatriya, Umang (GE Global Research); Bradley Lowekamp
Cc: insight-developers at itk.org
Subject: RE: [ITK-dev] [ITK] Thread Pool patch

I would at least remove the  "*2" from the initialization.

We could initialize the number of threads in the pool to 0 or 1.

But I don't understand why initializing threads for the thread pool may cause an error whereas initializing threads for a filter in the pre-thread pool implementation does not.  Both should be creating GetGlobalDefaultNumberOfThreads() threads in rapid succession.

Jim

From: Brahmakshatriya, Umang (GE Global Research)
Sent: Monday, April 07, 2014 9:28 AM
To: Bradley Lowekamp; Miller, James V (GE Global Research)
Cc: insight-developers at itk.org
Subject: RE: [ITK-dev] [ITK] Thread Pool patch

MultiThreader::MultiThreader() : m_ThreadPool(ThreadPool::New() )

187<javascript:void(0)>

{

188<javascript:void(0)>

  m_ThreadPool->InitializeThreads(GetGlobalDefaultNumberOfThreads() * 2);

I was aware of this issue and had mentioned about this to Jim - If we demand too many simumtaneous pthreads to be started, the pthread_create call returns error code 11 (http://pubs.opengroup.org/onlinepubs/7908799/xsh/pthread_create.html ). So if the above call returns the correct number of threads, I think we should be fine unless we are creating more than one "thread pools".

Umang Brahmakshatriya
Advanced Computing Lab
GE Global Research
1 Research Circle K1-3A37C
Niskayuna, NY 12309

From: Bradley Lowekamp [mailto:blowekamp at mail.nih.gov]
Sent: Monday, April 07, 2014 9:13 AM
To: Miller, James V (GE Global Research)
Cc: Brahmakshatriya, Umang (GE Global Research); insight-developers at itk.org<mailto:insight-developers at itk.org>
Subject: Re: [ITK-dev] [ITK] Thread Pool patch

Jim,

Yes it was. But I set ITK_GLOBAL_DEFAULT_NUMBER_OF_THREADS to 8, and did ctest -j 8 initially, then I scaled back from there with lack of complete success in testing. There are thread management issue with the current patch.

Brad

On Apr 4, 2014, at 2:06 PM, Miller, James V (GE Global Research) <millerjv at ge.com<mailto:millerjv at ge.com>> wrote:

"Too many threads" is a bit odd.  Umang does initialize the pool with a set of threads, then adds threads as needed. I believe the thread initialization is based on the number of cores.  But in principle, the initialization could be as low as 0 or 1 threads.

I missed that in the patch. This is what I saw:
m_Threadpool(m_Threadpoolfactory.GetSmartThreadPool(GetGlobalDefaul
tNumberOfThreads() * 2) )

185

{

Was this on one of your giant core machines?

Jim

Brad

On Apr 4, 2014, at 10:42 AM, Brahmakshatriya, Umang (GE Global Research) <brahmaks at ge.com<mailto:brahmaks at ge.com><mailto:brahmaks at ge.com>> wrote:

Hi All,

My name is Umang, I am working to submit the Thread Pool patch. Can anyone help me through the final steps of submitting it? I had a few issues creating the patches.
I am available next week at these times:
Tuesday 4/8 - 2.30p to 5p EST
Wednesday 4/9 -  9.30am to 12p EST
Thursday 4/10 - 2.30p to 5p EST

Let me know which time works best and I will setup a t-con and webex / google hangout.

Umang Brahmakshatriya
Advanced Computing Lab
GE Global Research
1 Research Circle K1-3A37C
Niskayuna, NY 12309

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