Warning "Multithreading is deprecated. Remove the num_threads input"

[HippocampusGirl]

What happened?

fMRIPrep version 25.2.3 (used through HALFpipe) prints the following warning message consistently for me:

Multithreading is deprecated. Remove the num_threads input.

The warning is raised here

niworkflows/niworkflows/interfaces/itk.py

Lines 70 to 71 in d991644

	if isdefined(self.inputs.num_threads):
	LOGGER.warning('Multithreading is deprecated. Remove the num_threads input.')

This happens because the num_threads input is set automatically by Nipype, so it will always be defined.
https://github.com/nipy/nipype/blob/a8d71305b7c16965192ad0156e6c8df25f6b0acf/nipype/pipeline/engine/nodes.py#L202-L203

Does anyone else also get this warning message?

What command did you use?

halfpipe

What version of the software are you running?

fMRIPrep 25.2.3

How are you running this software?

Docker

Is your data BIDS valid?

Yes

Are you reusing any previously computed results?

No

Please copy and paste any relevant log output.

[2026-04-13 13:12:17,0436] [nipype.interface] [WARNING  ] Multithreading is deprecated. Remove the num_threads input.

Additional information / screenshots

No response

[effigies]

Looks like that was my fault in #835. Need to think about how to remove its effect of claiming multiple threads without breaking callers.