reimplementation of gpu_count

[mauriliogenovese]

fix #3717

I tried to write a simpler implementation of getGPUs from gputil package.
I used a separate file to include their license.

This need to be tested under windows with Python 3.12+ and I don't have such system, so it's untested for now.

[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 73.05%. Comparing base (fe20d45) to head (c189912).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
nipype/utils/gpu_count.py	60.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3718      +/-   ##
==========================================
- Coverage   73.07%   73.05%   -0.03%     
==========================================
  Files        1278     1279       +1     
  Lines       59406    59414       +8     
==========================================
- Hits        43411    43404       -7     
- Misses      15995    16010      +15     

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[effigies]

We need to remove gputil from the dependencies.

I'm not terribly worried about Windows, as there are many years of development since last time anybody tried to get nipype working on Windows.

[mauriliogenovese]

We need to remove gputil from the dependencies.

Done

I'm not terribly worried about Windows, as there are many years of development since last time anybody tried to get nipype working on Windows.

I meant that I don't have a computer without a nvidia GPU to test if this code fix the error reported, I assumed it was on Windows. So even a test on other OS may be useful.

[effigies]

If the goal is to keep it as close to the source as possible, that's fine. Here are some cleanups for your consideration:

1. Use shutil.which() unconditionally. We can detect a FileNotFoundError before calling the process and simply return 0.
2. Use subprocess.run, which is the recommended API. By using text mode, we don't have to handle decoding or newline normalization.
3. Use targeted errors. FileNotFoundError and PermissionError (both OSErrors) should catch failures to run. UnicodeDecodeError will catch bad output.
4. Use p.output.splitlines() to get content-full lines. A trailing newline does not produce an empty string at the end of the list.

Suggested change

	from subprocess import Popen, PIPE
	import os
	def gpu_count():
	try:
	if platform.system() == "Windows":
	nvidia_smi = shutil.which('nvidia-smi')
	if nvidia_smi is None:
	nvidia_smi = (
	"%s\\Program Files\\NVIDIA Corporation\\NVSMI\\nvidia-smi.exe"
	% os.environ['systemdrive']
	)
	else:
	nvidia_smi = "nvidia-smi"
	p = Popen(
	[nvidia_smi, "--query-gpu=name", "--format=csv,noheader,nounits"],
	stdout=PIPE,
	)
	stdout, stderror = p.communicate()
	output = stdout.decode('UTF-8')
	lines = output.split(os.linesep)
	num_devices = len(lines) - 1
	return num_devices
	except:
	return 0
	import subprocess
	import os
	def gpu_count():
	nvidia_smi = shutil.which('nvidia-smi')
	if nvidia_smi is None and platform.system() == "Windows":
	nvidia_smi = f'{os.environ["systemdrive"]}\\Program Files\\NVIDIA Corporation\\NVSMI\\nvidia-smi.exe'
	if nvidia_smi is None:
	return 0
	try:
	p = subprocess.run(
	[nvidia_smi, "--query-gpu=name", "--format=csv,noheader,nounits"],
	stdout=subprocess.PIPE,
	text=True,
	)
	except (OSError, UnicodeDecodeError):
	return 0
	return len(output.splitlines())