[Octave-bug-tracker] [bug #60251] [octave-forge] (parallel) strange execution times

[Muhali]

URL:
  <https://savannah.gnu.org/bugs/?60251>

                 Summary: [octave-forge] (parallel) strange execution times
                 Project: GNU Octave
            Submitted by: muhali
            Submitted on: Wed 17 Mar 2021 09:51:55 AM PDT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 6.1.0
         Discussion Lock: Any
        Operating System: GNU/Linux

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Details:

As the code below shows, the newer parallel package (4.0.0, with octave-6) has
some strange execution time behavior.


pkg load parallel

n = 3000 ;
I = num2cell(1:n) ;

tic ;
C = parcellfun(nproc, @(x) 1:n == x, I, "UniformOutput", false,
"VerboseLevel", 0) ;
toc
tic ;
C = parcellfun(nproc, @(x) 1:n == x, I, "UniformOutput", false,
"VerboseLevel", 0) ;
toc


The result is

Elapsed time is 9.65733 seconds.
Elapsed time is 0.534994 seconds.

When doing the same with the old version (3.1.3, with octave-5) one gets

Elapsed time is 0.339917 seconds.
Elapsed time is 0.325187 seconds.





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