Re: multithreading

Here is the main part of the code, I left out allocate and deallocation...

It is slower then numTreads=12 than for numTreads = 1

I have 12 logically processors, the more I use the slower it goes.




		numThreadsRunning = 0;


		for (FXint i = 0; i < numTreads; i++)
		{
			FXArray<Material> materialsArray;

			for (int list_box_index = firstListBoxIndex[i]; list_box_index < lastListBoxIndex[i] + 1; list_box_index++)
			{
				int j_start = _listBoxDefinition[list_box_index].iStart;
				int j_end = _listBoxDefinition[list_box_index].iEnd;

				for (int j = j_start; j < j_end + 1; j++)
				{
					materialsArray.append(_materialsArray.at(j));
				}
			}

			// pass data to thread
			checkValuesThreadInitalizedOK[i] = checkValuesThread[i].passData(materialsArray, _lastArrayIndexInMatArrayBeforeUserMats, dt);

			if (checkValuesThreadInitalizedOK[i])
			{
				checkValuesThread[i].start();
				hThreadCheckValues[i] = checkValuesThread[i].id();
				numThreadsRunning++;
			}
		}


		while (true)
		{
			bool anyThreadsRunning = false;

			for (FXint i = 0; i < numTreads; i++)
			{
				if (checkValuesThread[i].running())
				{
					anyThreadsRunning = true;
					break;
				}
			}

			// if all threads are finished
			if (!anyThreadsRunning)
			{
				break;
			}

			// keep UI responsive
			if (getApp()->peekEvent())
			{
				getApp()->runWhileEvents();
			}
		} // while (true)



		for (FXint i = 0; i < numTreads; i++)
		{
			checkValuesThread[i].join();
		}




-----Original Message-----
From: Enno Rehling <[email protected]> 
Sent: Sunday, November 20, 2022 8:36 AM
To: [email protected]
Subject: Re: [Foxgui-users] multithreading

Hi John,

Your question lacks some important details. How is this related to Fox? 
What do you mean by "multithreaded a calculation"? Can you show some example code of what you are doing that would help to reproduce the problem?

Enno.

On 20-Nov-22 00:27, John Selverian wrote:
> I’m seeing a very strange problem. I just multithreaded a calculation 
> and it takes longer then running with a single thread. I’ve done 
> multithreading in the past with success so I don’t see what could be 
> going wrong. The overhead for each thread is very low so that’s not it.
> Any ideas?
> 
> Kind regards,
> 
> js
> 
> 
> 
> _______________________________________________
> Foxgui-users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/foxgui-users


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