[Fix] fix eval bug when single processing.

[zytx121]

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Motivation

fix bug in #10

Modification

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BC-breaking (Optional)

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Checklist

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2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. The documentation has been modified accordingly, like docstring or example tutorials.

[yangxue0827]

LGTM

[codecov-commenter]

Codecov Report

Merging #14 (08c1955) into main (6519a36) will decrease coverage by 0.02%.
The diff coverage is 18.75%.

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
- Coverage   28.92%   28.90%   -0.03%     
==========================================
  Files          97       97              
  Lines        6471     6477       +6     
  Branches      969      970       +1     
==========================================
  Hits         1872     1872              
- Misses       4534     4540       +6     
  Partials       65       65              

Flag	Coverage Δ
unittests	28.90% <18.75%> (-0.03%)	⬇️

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Impacted Files	Coverage Δ
mmrotate/datasets/dota.py	11.17% <18.75%> (-0.21%)	⬇️
mmrotate/models/detectors/base.py	25.00% <0.00%> (ø)
mmrotate/core/visualization/image.py	77.77% <0.00%> (ø)

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[jbwang1997]

Can we set the nproc as an input of the format_results function so that it can be modified by users?

[yangxue0827]

The user may be confused as to how much this parameter is set appropriately.

[jbwang1997]

We need to use a single process to call _merge_func when deadlock happened. But nproc = min(4, os.cpu_count()) is usually bigger than 1, which cannot make the program switch from `track_parallel_progress' to 'track_iter_progress'.

[ZwwWayne]

Baeed on previous conventions, we should add an argument of nproc in this function. Usually users can set 4 and this could accelerate the process. The users can also set 1 to avoid parallel processing manually. We can add description in the docstring and documentation.

[zytx121]

OK

[jbwang1997]

LGTM