[Swan-dev] testing hangs for me

[Andrew Cagney]

On Wed, 20 Mar 2019 at 23:49, D. Hugh Redelmeier <hugh at mimosa.com> wrote:
>
> | From: Andrew Cagney <andrew.cagney at gmail.com>
>
> | Next I'm trying:
> |    dnf downgrade python3
>
> Andrew seems to have found a Python bug report for this bug.  No fix,
> but a bug report:

Yea. I think its related - someone screwed up some locking - but I'm
not sure it is the same bug:
- the test case uses ProcessPoolExecutor (+fork()), kvmrunner.py uses
ThreadPoolExecutor (+fork() +exec() +...)
- their child process is stuck trying to get a mutex (for us I don't know)
- I've not managed to capture a good backtrace (the only one I have is
for poolsize=1 and it bizarrely shows code stuck in python's logger's
.emit() function making me wonder if it is even correct)
I think your most perternent observation is that the broken code runs
a lot faster.

And good to hear that we've a workaround.

#include rant about python's threading model being intrinsically flawed

> <https://bugs.python.org/issue35866?>
>
> WORKAROUND:
>
> For me, the last working packages for Fedora 29 are:
>
> <https://kojipkgs.fedoraproject.org//packages/python3/3.7.1/4.fc29/x86_64/python3-3.7.1-4.fc29.x86_64.rpm>
> <https://kojipkgs.fedoraproject.org//packages/python3/3.7.1/4.fc29/x86_64/python3-libs-3.7.1-4.fc29.x86_64.rpm>
>
> These and related packages can be found for multiple architectures and
> Fedora releases:
> <https://koji.fedoraproject.org/koji/buildinfo?buildID=1166440>
>
> I think that you can downgrade your system by doing a
>         sudo dnf install \
> https://kojipkgs.fedoraproject.org//packages/python3/3.7.1/4.fc29/x86_64/python3-3.7.1-4.fc29.x86_64.rpm \
> https://kojipkgs.fedoraproject.org//packages/python3/3.7.1/4.fc29/x86_64/python3-libs-3.7.1-4.fc29.x86_64.rpm
>
> I haven't tried that.  Instead, I downloaded the files to my machine
> and used a file path to refer to them.  I think that the path needs a
> / in it to distinguish it from a package name:
>
>         sudo dnf install \
>                 ./python3-3.7.1-4.fc29.x86_64.rpm \
>                 ./python3-libs-3.7.1-4.fc29.x86_64.rpm