Parallel Computing Toolbox: Underperformance AND Cannot cancel or destroy a job that was not created by this Local cluster.

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I am running Win Server 2012 R2 with 2014A with PCT. I have two questions.
Question 1:
I keep getting the below warning,
Warning: Cannot cancel or destroy a job that was not created by this Local cluster.
> In Local.cancelOrDestroyJob at 34
In Local.Local>Local.hDestroyJob at 237
In CJSJobMethods>CJSJobMethods.destroyOneJob at 70
In CJSCommunicatingJob>CJSCommunicatingJob.destroyOneJob at 94
In Job.Job>Job.delete at 1037
In my_mFile at 39
Starting parallel pool (parpool) using the 'local' profile ... connected to 32 workers.
My code looks like,
myCluster = parcluster('local');
A = length(myFiles);
parfor a = 1: A
%do stuff
The reason I included "delete(myCluster.Jobs);" is that without it I get another warning, as below. I should say I only have one MATLAB IDE running at anyone time on my machine.
Warning: Found 1 pre-existing communicating job(s) created by pool that are running. You can use 'delete(myCluster.Jobs)' to remove
all jobs created with profile local. To create 'myCluster' use 'myCluster = parcluster('local')'.
What code do I need to change/include to make sure I do not get any warning?
Question 2:
I have 32 vCPU (vCPU = half a physical core, ie half of a shared core, or one hyperthread), (Intel Xeon E5-2680 v2) on my machine. The task I am trying to run is very demanding (each task takes c. 3mins to run). Hence I want to make sure the machine is maxed out.
In the MATLAB IDE I go to HOME, parallel, manage cluster profiles, edit and change "Number of Workers to start on your local machine" to 32.
I start the job. Task manager shows the total CPU at 40-50%. Going into resource monitor shows the individual matlab.exe taking up 0.2% CPU on average.
Is this right? Normally when I use PCT (on a normal/low spec machine) and don't set myCluster, parpool(local,32) etc) I get CPU useage of 100%.
When I remove the two lines:
myCluster = parcluster('local');
and then run the job, I see CPU now averages at >90%. No idea why...
  2 comentarios
Darwin Brochero
Darwin Brochero el 18 de Dic. de 2014
Renaming file gives an error in new parpool sessions, so in my case I save original configuration file with some prefix (orig-matlab_metadata.mat), and when I have this warning, I copy this file as "matlab_metadata.mat" to avoid this problem.
...That's still as a not technical fix, I know, but it's works.

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Respuestas (1)

Sean de Wolski
Sean de Wolski el 18 de Dic. de 2014
Editada: Sean de Wolski el 18 de Dic. de 2014
The only time I have seen that is also when something failed in a previous MATLAB session (hang/out of memory/etc.)
You should be able to clear them out in the job monitor.


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