Re: test harness hang running functional test

[Thomas Huth <thuth@redhat.com>]

On 07/11/2024 17.09, Peter Maydell wrote:
> I was trying to track down why one of the functional tests was
> hanging, so I tried running it directly:
> 
> UBSAN_OPTIONS=halt_on_error=1:abort_on_error=1
> QEMU_TEST_QEMU_BINARY=build/clang/qemu-system-loongarch64
> PYTHONPATH=./build/clang/pyvenv:./python time
> ./build/clang/pyvenv/bin/python3
> ./tests/functional/test_loongarch64_virt.py
> 
> (This is with a QEMU built with the undefined-behaviour
> sanitizer.)
> 
> Mostly this seems to succeed, but this time it's hung. Looking
> at the process tree:
> 
> petmay01 3616444  0.0  0.0   4768  1124 pts/2    S+   15:53   0:00
>   \_ time ./build/clang/pyvenv/bin/python3
> ./tests/functional/test_loongarch64_virt.py
> petmay01 3616445 99.8  0.0  38480 23620 pts/2    R+   15:53  13:20
>       \_ ./build/clang/pyvenv/bin/python3
> ./tests/functional/test_loongarch64_virt.py
> petmay01 3616448  0.0  0.0      0     0 pts/2    Z+   15:53   0:00
>           \_ [qemu-system-loo] <defunct>
> 
> The QEMU process itself has exited, but the test harness has
> not yet noticed or reaped the zombie process. Instead it's sitting
> there eating CPU. Presumably this is a bug in the test harness?

Sounds like either a bug in the test harness or in the "python/qemu" module 
... I'll try to look at it, but maybe not in the next two weeks (I'm 
currently quite busy with other stuff), so if someone else wants to have a 
look already, that would be great!

  Thomas