Perf/allocation optimizations for FastLabelPropagationCommunityDetector.AssignLabels

[gmanvel]

Description

Removed Cache benchmark as it's not adding much value, it benchmarks operations on in memory cache.
Added test coverage for FastLabelPropagationCommunityDetector.AssignLabels method.
Applied perf/allocation improvements to AssignLabels method.

Proposed Changes

Applying small tweaks to reduce allocations, by using random.shuffle to shuffle in-place instead of creating a new list. Also moved labelWeights dictionary creation outside of the loop to reduce allocations further.

BenchmarkDotNet results:

Method	MaxIterations	Mean	Ratio	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
SmallGraph	10	137.1 μs	1.00	43.9453	3.9063	-	360.23 KB	1.00
SmallGraphOptimized	10	107.0 μs	0.78	19.7754	1.7090	-	161.79 KB	0.45
MediumGraph	10	4,409.8 μs	32.17	929.6875	460.9375	-	7622.17 KB	21.16
MediumGraphOptimized	10	3,501.4 μs	25.54	292.9688	128.9063	-	2412.64 KB	6.70
LargeGraph	10	51,760.4 μs	377.57	8300.0000	1400.0000	400.0000	65432.8 KB	181.64
LargeGraphOptimized	10	48,501.6 μs	353.80	3181.8182	1363.6364	363.6364	23987.92 KB	66.59
SmallGraph	20	133.8 μs	1.00	43.9453	3.9063	-	360.23 KB	1.00
SmallGraphOptimized	20	109.6 μs	0.82	19.7754	1.7090	-	161.79 KB	0.45
MediumGraph	20	4,468.4 μs	33.40	929.6875	460.9375	-	7622.17 KB	21.16
MediumGraphOptimized	20	3,551.9 μs	26.55	292.9688	128.9063	-	2412.64 KB	6.70
LargeGraph	20	53,121.9 μs	397.07	8300.0000	1400.0000	400.0000	65432.76 KB	181.64
LargeGraphOptimized	20	49,651.3 μs	371.13	3200.0000	1300.0000	400.0000	23987.96 KB	66.59
SmallGraph	40	141.4 μs	1.00	43.9453	3.9063	-	360.23 KB	1.00
SmallGraphOptimized	40	109.8 μs	0.78	19.7754	1.7090	-	161.79 KB	0.45
MediumGraph	40	4,637.3 μs	32.79	929.6875	460.9375	-	7622.17 KB	21.16
MediumGraphOptimized	40	3,567.2 μs	25.22	292.9688	128.9063	-	2412.64 KB	6.70
LargeGraph	40	53,164.4 μs	375.88	8300.0000	1400.0000	400.0000	65432.76 KB	181.64
LargeGraphOptimized	40	49,436.0 μs	349.52	3200.0000	1300.0000	400.0000	23988.3 KB	66.59

Which are big in allocation improvement & up to 20 % performance improvement.

Iterations	Graph Size	Mean Improvement (%)	Allocation Improvement (%)
10	Small	21.9%	55.1%
10	Medium	20.6%	68.3%
10	Large	6.3%	63.3%
20	Small	18.1%	55.1%
20	Medium	20.5%	68.3%
20	Large	6.5%	63.3%
40	Small	22.4%	55.1%
40	Medium	23.1%	68.3%
40	Large	7.0%	63.3%

Checklist

• I have tested these changes locally.
• I have reviewed the code changes.
• I have updated the documentation (if necessary).
• I have added appropriate unit tests (if applicable).

Additional Notes

N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.24%. Comparing base (41b89ca) to head (feb6294).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #5      +/-   ##
==========================================
- Coverage   75.34%   75.24%   -0.11%     
==========================================
  Files         115      115              
  Lines        4734     4751      +17     
  Branches      797      798       +1     
==========================================
+ Hits         3567     3575       +8     
- Misses        851      861      +10     
+ Partials      316      315       -1     

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[KSemenenko]

I absolutely love your work! Thanks a lot!