Error Implementing parfor while creating satellite objects

I am having trouble parallelizing a working for loop that reads in TLE files to generate satellite objects via the Aerospace Toolbox.

StarlinkTLE=tleread('constellation.txt'); %pulls in TLEs from the attached "constellation.txt" file
load("FlightDataTimeTable.mat"); %pulls in a timetable with 10 sec increments and Lat/Long/Altitude of an aircraft
a=length(StarlinkTLE); %number of TLEs = number of Satellites...

[r,v]=propagateOrbit(datetime('now')+FlightDataTimeTable.Time,StarlinkTLE); %creates unique position and
%  velocity for each satellite at each aircraft time increment, (I'm aware I'm not using v anyware later on yet)

mySatArr = cell(1,a); %placeholder cell structure to catch the satellites as they're made (included for parfor)

for ii=1:20 % 1:a satellites when parfor is working...
    sat_pos=timetable(FlightDataTimeTable.Time,r(:,:,ii)'); %creates a position table to generate satellite object
    try
        mySatArr{ii}=satellite(sc,sat_pos,'Name',StarlinkTLE(ii).Name); %puts satellite object in mySatArr cell, and fixes name
    catch
        % An unknown # of the TLEs intersect the earth, and this leaves those
        % cells empty
    end

end

The parfor variation below kicks out the below error.

"Error using StarlinkConstellation

Invalid default value for property 'ColorConverter' in class 'matlabshared.satellitescenario.ScenarioGraphic':

The specified superclass 'matlab.graphics.internal.GraphicsBaseFunctions' contains a parse error, cannot be found

on MATLAB's search path, or is shadowed by another file with the same name."

StarlinkTLE=tleread('constellation.txt');
load("FlightDataTimeTable.mat");
a=length(StarlinkTLE);

[r,v]=propagateOrbit(datetime('now')+FlightDataTimeTable.Time,StarlinkTLE);

mySatArr = cell(1,a);

parfor ii=1:20 %only change to above code...
    sat_pos=timetable(FlightDataTimeTable.Time,r(:,:,ii)');
    try
        mySatArr{ii}=satellite(sc,sat_pos,'Name',StarlinkTLE(ii).Name);
    catch

    end

end

The for loop finds the GraphicsBaseFunctions just fine, which tells me the constructor isn't missing...

>> which -all matlab.graphics.internal.GraphicsBaseFunctions

matlab.graphics.internal.GraphicsBaseFunctions is a built-in method % matlab.graphics.internal.GraphicsBaseFunctions constructor

I'm blindly guessing this is related to a single class constructor being reserved by the first worker, which is why the second worker tries and fails to use the built-in method, thus throwing the error.

Any help/guidance/sagely-smack-in-the-back-of-the-head is welcome.

Thanks for reading!

Answer 1

[Edric Ellis]

I'm guessing you are trying to use this with a thread-based parallel pool. I had to add a line to your code to make it work, namely:

sc = satelliteScenario;

With this, I see that there is a problem when using a thread-base parallel pool, but that things work correctly if you use a process pool.

[Jon]

Thanks for the guidance! Didn't realize this was a thing, so I'll go dive into the parallel computing fundamentals to fix my knowledge gap....