PYTHONHOME issue?

I had cocotb running in our work environment only last week or so, but something has started to cause the following issue.

I’m on CentOS 7 and the SIM=xcelium

The simple_dff example appears to die the same way, so here’s the output from that:

        module worklib.dff:sv
                errors: 0, warnings: 0
     -.--ns INFO     cocotb.gpi                         ..mbed/gpi_embed.cpp:74   in set_program_name_in_venv        Did not detect Python virtual environment. Using system-wide Python interpreter
Fatal Python error: Py_Initialize: Unable to get the locale encoding
ModuleNotFoundError: No module named 'encodings'

Current thread 0x00007fa44e62ee00 (most recent call first):
ImportError: No module named site
xmelab: *F,INTERR: INTERNAL EXCEPTION

Some output from cocotb-config:

$ cocotb-config --version
1.4.0rc1
$ cocotb-config --python-bin
/usr/bin/python3
$ cocotb-config --prefix
/usr/local/lib64/python3.6/site-packages

Running the following (as per Makefile.inc’s way of calculating PYTHONHOME):

$ /usr/bin/python3 -c 'from distutils.sysconfig import get_config_var; print(get_config_var("prefix"))'
/usr

An interesting observation (I think anyway?) is if I set PYTHONHOME to /usr/local under which the site-packages/cocotb is really located (as per the cocotb-config output), I see the same crash.

$ PYTHONHOME=/usr /usr/bin/python3
Python 3.6.8 (default, Apr  2 2020, 13:34:55)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

$ PYTHONHOME=/usr/local /usr/bin/python3
Fatal Python error: Py_Initialize: Unable to get the locale encoding
ModuleNotFoundError: No module named 'encodings'

Current thread 0x00007f4ce0135740 (most recent call first):
Aborted

Any ideas? I’m quite certain this worked only a week ago, I just updated to the latest cocotb, but I’m not ruling out something changing on my system, too.

Thanks for any pointers, and great job with cocotb so far all!!

[thasti]

Yes, I will attempt to recreate the failure mode. To make it clear: Things started working after removing the hacks that injected libpython via LD_LIBRARY_PATH. These used to work for older versions of Xcelium, but stopped working with Xcelium 20.

Since I was recently able to get the python development packages installed on the systems in question, I do not need to perform these hacks anymore and cocotb works as-is, even in a venv.

[imphil]

The probably easiest option for a bisect is to clone the cocotb repository, and then install with pip from the repository.

git clone https://github.com/cocotb/cocotb
cd cocotb
pip install .

Then you can either use git bisect or just manually go back to a commit a couple weeks back. Re-run pip install . after you’ve checked out a different commit.