I experienced the same problem with the routine LAPACKE_dsyevd with a 6x6 matrix. I tried to check the eigenvalues with GNU/Octave and .. it got stuck as well! The code was working a few days ago with Ubuntu 19.10 before the upgrade to 20.04.
The backtrace is:
#0 0x00007ffff599f70b in sched_yield () at ../sysdeps/unix/syscall-template.S:78
#1 0x00007ffff614cfa5 in exec_blas_async_wait () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#2 0x00007ffff614d07c in exec_blas () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#3 0x00007ffff5f693cc in dsymv_thread_U () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#4 0x00007ffff5f251ae in dsymv_ () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#5 0x00007ffff7ad09f5 in dsytd2_ () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#6 0x00007ffff7ad536d in dsytrd_ () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#7 0x00007ffff7ac66cc in dsyevd_ () from /usr/lib/x86_64-linux-gnu/libopenblas.so.0
#8 0x00007ffff5cd76e0 in LAPACKE_dsyevd_work () from /usr/lib/x86_64-linux-gnu/liblapacke.so.3
#9 0x00007ffff5cd70b7 in LAPACKE_dsyevd () from /usr/lib/x86_64-linux-gnu/liblapacke.so.3
I experienced the same problem with the routine LAPACKE_dsyevd with a 6x6 matrix. I tried to check the eigenvalues with GNU/Octave and .. it got stuck as well! The code was working a few days ago with Ubuntu 19.10 before the upgrade to 20.04.
The backtrace is: unix/syscall- template. S:78 async_wait () from /usr/lib/ x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ libopenblas. so.0 x86_64- linux-gnu/ liblapacke. so.3 x86_64- linux-gnu/ liblapacke. so.3
#0 0x00007ffff599f70b in sched_yield () at ../sysdeps/
#1 0x00007ffff614cfa5 in exec_blas_
#2 0x00007ffff614d07c in exec_blas () from /usr/lib/
#3 0x00007ffff5f693cc in dsymv_thread_U () from /usr/lib/
#4 0x00007ffff5f251ae in dsymv_ () from /usr/lib/
#5 0x00007ffff7ad09f5 in dsytd2_ () from /usr/lib/
#6 0x00007ffff7ad536d in dsytrd_ () from /usr/lib/
#7 0x00007ffff7ac66cc in dsyevd_ () from /usr/lib/
#8 0x00007ffff5cd76e0 in LAPACKE_dsyevd_work () from /usr/lib/
#9 0x00007ffff5cd70b7 in LAPACKE_dsyevd () from /usr/lib/