[Octave-bug-tracker] [bug #60762] Repeatable crash on exit when OPENBLAS_NUM_THREADS is set to 6

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?60762>

                 Summary: Repeatable crash on exit when OPENBLAS_NUM_THREADS
is set to 6
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Thu 10 Jun 2021 12:19:02 AM UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Segfault, Bus Error, etc.
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: dev
         Discussion Lock: Any
        Operating System: GNU/Linux

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Details:

While testing the effect of OPENBLAS_NUM_THREADS I found this repeatable crash
on exit. It does not affect anything on the user side except crashing on exit
when that environment variable is touched, and the user-size solution is to
not mess with that variable. This bug report is to bring it to the devs'
attention in case it's a bigger problem.

For reference, this is on a CPU with 6 cores and 12 threads. The OpenBLAS
version is 0.3.15 and installed from the distro package.

Abnormal exit when using OPENBLAS_NUM_THREADS=6:

$ OPENBLAS_NUM_THREADS=6 octave -q    ### <------ THIS LINE IS THE ONLY
DIFFERENCE IN INPUT
octave:1> load bench
octave:2> whos
Variables visible from the current scope:

variables in scope: top scope

   Attr Name        Size                     Bytes  Class
   ==== ====        ====                     =====  ===== 
        adj       528x528                  1115136  single

Total is 278784 elements using 1115136 bytes

octave:3> bak = adj;
octave:4> tic; for i = 1:1e3, A = bak; for j = 1:10, A = min (A+A^2, 1); end;
end; toc
Elapsed time is 11.3746 seconds.
octave:5> tic; for i = 1:1e3, A = bak; for j = 1:10, A = min (A+A^2, 1); end;
end; toc
Elapsed time is 11.3877 seconds.
octave:6> exit                        ### <------ CRASH HERE
fatal: caught signal Segmentation fault -- stopping myself...
Segmentation fault (core dumped)


Normal operation leaving OPENBLAS_NUM_THREADS to its default:

$ octave -q                           ### <------ THIS LINE IS THE ONLY
DIFFERENCE IN INPUT
octave:1> load bench
octave:2> whos
Variables visible from the current scope:

variables in scope: top scope

   Attr Name        Size                     Bytes  Class
   ==== ====        ====                     =====  ===== 
        adj       528x528                  1115136  single

Total is 278784 elements using 1115136 bytes

octave:3> bak = adj;
octave:4> tic; for i = 1:1e3, A = bak; for j = 1:10, A = min (A+A^2, 1); end;
end; toc
Elapsed time is 11.3243 seconds.
octave:5> tic; for i = 1:1e3, A = bak; for j = 1:10, A = min (A+A^2, 1); end;
end; toc
Elapsed time is 11.3759 seconds.
octave:6> exit                        ### <------ NORMAL EXIT






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