segfault in getOptimalThreadCount

[jml70]

I am testing a build of finufft-2.4.1 using the MATLAB interface and run into a segmentation fault triggered by getOptimalThreadCount. It appears to occur when the OMP_NUM_THREADS environment variable is not set.

uname -a
Linux XXXXXXX 3.10.0-1160.36.2.el7.x86_64 #1 SMP Thu Jul 8 02:53:40 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

MATLAB crash dump, CMakeLists.txt attached

matlab_crash_dump.txt

CMakeLists.txt

[DiamonDinoia]

That's a very old kernel. What OS is this?
Could you post the contents of /proc/cpuinfo ?

The easiest way to debug is to add some prints in the function to find out what fails.

I created a branch that tried to fail-over gracefully. Can you try it? https://github.com/DiamonDinoia/finufft/tree/thread-count-segfaults

[DiamonDinoia]

@jml70 could you check that master does the trick for you?