[srsran-users] srsUE container breaks when run using Python subprocess

[Antonio Albanese]

Hey guys,

a bit of a particular question for those of you who have experimented with
srsRAN and docker.

I built a docker image for srsRAN 21.10 based on Ubuntu 20.04. I am aware
that this is not the latest srsRAN release but it should be unrelated to my
issue, I hope!

I am experiencing a weird behavior, particularly with srsue. I am using a
bladerf 2.0 xA4, which comes with its own problems with srsue (see the open
issue on the Nuand github about the board easily getting stuck when
changing sampling rate). Nonetheless, I managed to have a working srsRAN
image for srsepc, srsenb and srsue.

I can run it using docker-compose with docker-compose up srsue with *no
problem*. However, whenever I call it from Python with

import subprocess
cmd = "docker-compose up --detach srsue"
p = subprocess.Popen(cmd, cwd=paths["docker"], shell=True)

srsue never tries to attach. I had this in the past and it all boiled down
to srsue failing to lock synchronization with PSS and SSS. I have not
looked into the logs and the PCAPs yet, just because it is a little more
cumbersome to extract them from a container but I will. Anyway, I would not
know what to do if they confirmed my assumption.

To make matters worse, I can run the container in terminal with the CPU
governor in power save mode while I cannot run it from Python even in
performance mode.

I wonder how Python is increasing the overhead on the container here or
even if the problem is Python or something else altogether!
Please note that I also tried with  stdout=subprocess.PIPE,
stderr=subprocess.PIPE reading the console output using  p.stdout.readline for
that matter.

Lastly, something else that I found quite interesting (I let you imagine
how long it took to figure this out). The container would not work using
Ubuntu 22.04 as base and I had to downgrade it to 20.04 to have it stable.
This happens also at host level, meaning that I have a clean installation
of Ubuntu 22.04 that would not run srsue on bare metal but it would in a
container using Ubuntu 20.04 as base (in fact, Ubuntu 20.04 host would run
srsue on bare metal too). The same Ubuntu 22.04 is the host I use when I
call the container from Python, maybe this somehow affects things?

I will keep troubleshooting the problem. Meanwhile, has anyone had any
similar experience and would like to share any hints?
Thank you very much!

Cheers,
Antonio






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