perf: introduce stack cache

[P403n1x87]

We hash stacks so that we can cache them when emitting data in the binary format.

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Description of the Change

Alternate Designs

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Verification Process

[codecov]

Codecov Report

Attention: Patch coverage is 93.18182% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 68.36%. Comparing base (4559915) to head (263d51d).

Files	Patch %	Lines
src/py_proc.c	50.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            devel     #218      +/-   ##
==========================================
- Coverage   68.54%   68.36%   -0.19%     
==========================================
  Files          27       27              
  Lines        2521     2557      +36     
  Branches      771      779       +8     
==========================================
+ Hits         1728     1748      +20     
- Misses        453      466      +13     
- Partials      340      343       +3     

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[github-actions]

Austin Benchmarks

Running Austin benchmarks with Python 3.10.14

Benchmark Summary

Comparison of dev against 3.6.0.

The following scenarios show a statistically significant difference in performance between the two versions.

	Sample Rate	Saturation	Error Rate	Sampling Speed
Wall time [sampling interval: 1]	🟢	🟢	🟢	🟡
Wall time [sampling interval: 10]	🟡	🟡	🟢	🟢
CPU time [sampling interval: 1]	🟡	🟡	🟢	🟡
CPU time [sampling interval: 10]	🟡	🟡	🟢	🟡
CPU time [sampling interval: 100]	🟡	🟡	🟢	🟡
RSA keygen [sampling interval: 1]	🟡	🟡	🟢	🟡
RSA keygen [sampling interval: 100]	🟡	🟡	🟢	🟡
Full metrics [sampling interval: 1]	🟡	🟡	🟢	🟡
Full metrics [sampling interval: 10]	🟡	🟢	🟢	🟡
Full metrics [sampling interval: 100]	🔴	🟡	🟡	🟡
Multiprocess wall time [sampling interval: 1]	🟡	🟡	🟢	🟡
Multiprocess wall time [sampling interval: 10]	🟡	🟡	🟢	🟡
Multiprocess wall time [sampling interval: 100]	🟡	🟡	🟢	🟡

Benchmark Results

Wall time [sampling interval: 1]

Wall time [sampling interval: 1]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	192000 ± 2000	1 ± 0	6e-06 ± 4e-06	7.9 ± 0.3
dev	197000 ± 3000	0.99999 ± 1e-05	1e-06 ± 1e-06	7.6 ± 0.5

Wall time [sampling interval: 10]

Wall time [sampling interval: 10]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	65000 ± 7000	0.37 ± 0.04	1.6e-05 ± 8e-06	9.9 ± 0.3
dev	63000 ± 5000	0.35 ± 0.03	6e-06 ± 4e-06	9.2 ± 0.4

Wall time [sampling interval: 100]

Wall time [sampling interval: 100]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	12300 ± 200	0.0005 ± 0.0002	1e-05 ± 3e-05	9.3 ± 0.7
dev	12400 ± 200	0.0005 ± 0.0002	0.0 ± 2e-05	8.7 ± 0.5

Wall time [sampling interval: 1000]

Wall time [sampling interval: 1000]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	1860 ± 20	0 ± 0	0.0 ± 0.0001	10.7 ± 0.8
dev	1870 ± 20	0 ± 0	0 ± 0	10 ± 1

CPU time [sampling interval: 1]

CPU time [sampling interval: 1]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	61000 ± 3000	1 ± 0	1.4e-05 ± 8e-06	13.0 ± 0.7
dev	61000 ± 2000	1 ± 0	4e-06 ± 5e-06	12.9 ± 0.6

CPU time [sampling interval: 10]

CPU time [sampling interval: 10]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	57000 ± 3000	0.61 ± 0.05	1e-05 ± 1e-05	13.1 ± 0.3
dev	57000 ± 4000	0.6 ± 0.06	2e-06 ± 4e-06	13.2 ± 0.4

CPU time [sampling interval: 100]

CPU time [sampling interval: 100]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	6370 ± 20	0.0006 ± 0.0002	6e-05 ± 6e-05	17.3 ± 0.9
dev	6371 ± 9	0.0006 ± 0.0002	0 ± 0	16.7 ± 0.8

CPU time [sampling interval: 1000]

CPU time [sampling interval: 1000]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	947 ± 2	0 ± 0	0 ± 0	20.8 ± 0.6
dev	947 ± 2	0 ± 0	0 ± 0	20 ± 2

RSA keygen [sampling interval: 1]

RSA keygen [sampling interval: 1]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	61000 ± 4000	1 ± 0	7e-05 ± 6e-05	15.7 ± 0.9
dev	60000 ± 3000	1 ± 0	3e-06 ± 1e-05	16 ± 1

RSA keygen [sampling interval: 10]

RSA keygen [sampling interval: 10]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	58000 ± 3000	0.995 ± 0.003	0.00012 ± 7e-05	16.2 ± 0.9
dev	59000 ± 6000	0.994 ± 0.006	4e-05 ± 7e-05	16 ± 2

RSA keygen [sampling interval: 100]

RSA keygen [sampling interval: 100]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	6350 ± 30	0.001 ± 0.001	0.0005 ± 0.0004	20 ± 3
dev	6340 ± 20	0.001 ± 0.001	0 ± 0	21 ± 3

RSA keygen [sampling interval: 1000]

RSA keygen [sampling interval: 1000]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	945.1 ± 0.9	0 ± 0	0.001 ± 0.001	22 ± 4
dev	944 ± 2	0 ± 0	0.0 ± 0.001	23 ± 5

Full metrics [sampling interval: 1]

Full metrics [sampling interval: 1]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	74000 ± 2000	1 ± 0	1.2e-05 ± 7e-06	20.2 ± 0.6
dev	75000 ± 2000	1 ± 0	0 ± 0	19.8 ± 0.6

Full metrics [sampling interval: 10]

Full metrics [sampling interval: 10]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	76000 ± 1000	0.9 ± 0.02	1.4e-05 ± 8e-06	19.5 ± 0.7
dev	77000 ± 2000	0.86 ± 0.02	0 ± 0	19.3 ± 0.5

Full metrics [sampling interval: 100]

Full metrics [sampling interval: 100]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	12500 ± 200	0.0011 ± 0.0002	2e-05 ± 3e-05	25 ± 1
dev	12300 ± 100	0.001 ± 0.0002	0 ± 0	24 ± 1

Full metrics [sampling interval: 1000]

Full metrics [sampling interval: 1000]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	1860 ± 30	0 ± 0	0.0001 ± 0.0002	28 ± 1
dev	1860 ± 20	0 ± 0	0.0 ± 0.0001	27 ± 2

Multiprocess wall time [sampling interval: 1]

Multiprocess wall time [sampling interval: 1]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	7100 ± 700	1 ± 0	9e-05 ± 3e-05	132 ± 8
dev	7300 ± 500	1 ± 0	2e-05 ± 2e-05	132 ± 8

Multiprocess wall time [sampling interval: 10]

Multiprocess wall time [sampling interval: 10]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	6600 ± 1000	0.9978 ± 0.0005	7e-05 ± 3e-05	137 ± 4
dev	7100 ± 300	0.999 ± 0.002	1e-05 ± 1e-05	135 ± 5

Multiprocess wall time [sampling interval: 100]

Multiprocess wall time [sampling interval: 100]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	6400 ± 800	0.018 ± 0.005	4e-05 ± 3e-05	130 ± 20
dev	6970 ± 80	0.021 ± 0.001	1e-05 ± 1e-05	137 ± 2

Multiprocess wall time [sampling interval: 1000]

Multiprocess wall time [sampling interval: 1000]

	Sample Rate	Saturation	Error Rate	Sampling Speed
3.6.0	6500 ± 100	0.0013 ± 0.0002	1e-05 ± 2e-05	41 ± 1
dev	6510 ± 90	0.0013 ± 0.0002	3e-06 ± 7e-06	40 ± 1