Parallel Delaunay crashes on cube.obj with the Risc-V-64 version

[BrunoLevy]

Parallel Delaunay crashes on cube.obj with the Risc-V-64 version See here (64 Risc-V cores, 8 vertices)

• it is only the parallel version
• the debug version catches an out of bound access here
• maybe when there are more threads than vertices ?
• but it does not crash on my machine with 8 cores / 16 threads

[kxxt]

It also does not crash in riscv64 qemu-user emulation with 32 cpus on a x86_64 host machine. And doesn't crash on the same x86_64 host that has 16 cores and 32 threads.

[kxxt]

And if I force it to use 32 cores by hardcoding it in src/lib/geogram/basic/process_unix.cpp. It also no longer crashes on 64 core riscv64 machine.

[kxxt]

Looks like things already go wrong here:

pool_begin and pool_end are both zeros and due to unsignedness the condition t<pool_end-1 will evaluate to true.

https://github.com/BrunoLevy/geogram/blob/01f95b34bfd0fa2b03d5f86b2a56a35025d86e48/src/lib/geogram/delaunay/parallel_delaunay_3d.cpp#L163-L170

[kxxt]

141 fixes it

[BrunoLevy]

Great, thanks !!!