FIX: Copy num_threads to MapNode-generated Nodes

[effigies]

This PR copies the num_threads attribute from source MapNode's interface to those of the generated nodes.

Fixes #2016

[satra]

lgtm - seems like a simple fix to incorporate in 0.13.1

[effigies]

Actually, I should probably copy the memory estimate, too.

For a test, I can do something like:

mapnode = pe.MapNode(...)
nodes = list(mapnode._make_nodes())
for node in nodes:
    for attr in attrs_we_care_about:
        assert getattr(node, attr) == getattr(mapnode, attr)

Any other candidates for attrs_we_care_about?

[satra]

quick question, why doesn't the deepcopy a few lines (1115) back copy num_threads?

[effigies]

I have no idea. But you can run _make_nodes and check for yourself.

I could instead add a BaseInterface.__deepcopy__ function.

[satra]

In [6]: node = MapNode(BET(), iterfield=['in_file'], name='test')

In [7]: node._interface.num_threads
Out[7]: 1

In [8]: node._interface.num_threads = 5

In [9]: node._interface.num_threads
Out[9]: 5

In [10]: node.interface.num_threads
Out[10]: 5

In [11]: node.interface.num_threads = 4

In [12]: node._interface.num_threads
Out[12]: 4

In [13]: from copy import deepcopy

In [14]: deepcopy(node._interface).num_threads
Out[14]: 4

will check _make_nodes shortly

[effigies]

Try:

>>> pe.Node(deepcopy(node._interface), name='copynode')._interface.num_threads

[effigies]

Oh, I see the problem: In Node.__init__, self._interface.num_threads = n_procs, which is 1 by default...

[satra]

so the issue is with this line:

https://github.com/nipy/nipype/blob/master/nipype/pipeline/engine/nodes.py#L173

therefore in MapNodes, the deepcopy statement should include n_procs=self._interface.num_threads

Node(deepcopy(node._interface), 
     name='copynode', 
     n_procs=node._interface.num_threads)._interface.num_threads

and also any other attribute that's being set there.

[codecov-io]

Codecov Report

Merging #2019 into master will increase coverage by <.01%.
The diff coverage is 93.33%.

@@            Coverage Diff            @@
##           master   #2019      +/-   ##
=========================================
+ Coverage   72.19%   72.2%   +<.01%     
=========================================
  Files        1132    1132              
  Lines       57012   57023      +11     
  Branches     8162    8165       +3     
=========================================
+ Hits        41161   41173      +12     
+ Misses      14567   14566       -1     
  Partials     1284    1284

Flag	Coverage Δ
#smoketests	72.2% <93.33%> (ø)	⬆️
#unittests	69.79% <93.33%> (ø)	⬆️

Impacted Files	Coverage Δ
nipype/pipeline/engine/nodes.py	84.88% <100%> (+0.21%)	⬆️
nipype/pipeline/engine/tests/test_engine.py	93.52% <92.85%> (-0.03%)	⬇️

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[effigies]

@satra I moved all the parameters that could be moved into the Node(). Seem reasonable?