[Windows] OSError: [WinError 87] The parameter is incorrect

[phaniparsa]

Summary

• OS: Windows
• Architecture: 64bit, Intel(R) Xeon(R) CPU E5-2673 v3@2.40 GHz
• Psutil version: 5.9.0
• Python version: 3.9.13
• Type: { core, doc, performance, scripts, tests, wheels, new-api, installation }

Description

I am running the code available in this Git Repo: https://github.com/Merck/Line-of-Therapy-Algorithm/blob/master/Python/rwToT_LoT_main_parallel.py

and especially with the below lines of code:
ctx = multiprocessing.get_context('spawn')
pool = ctx.Pool(nprocesses)
processes = [p.pid for p in pool._pool]
for pid in processes:
p = psutil.Process(pid)
p.nice(5)
pool_results = pool.map(process_chunk, input_chunk)
pool.close()

When setting the niceness value for the process (process was created using multiprocessing), code is throwing the below error:

Could you please confirm if this is Bug? If not, could anyone please help me in fixing me this error. Thank you.

[giampaolo]

What happens if instead of passing it a number (5) you pass one of the *_PRIORITY_CLASS constants?
https://psutil.readthedocs.io/en/latest/#psutil.REALTIME_PRIORITY_CLASS