WIP: Improve audit time

[oraluben]

Motivation: We're using auditwheel to repair our internal PyTorch build, the overall time is ~10m. We're attempting to reduce the redundant operations that we've found, e.g. unzips.

This PR is not finalized yet but reviews are welcome!

• add log for time-consuming parts
• do not re-unzip wheel if possible
• multiprocess grafting libs
• set default compress level to 4
• tests
• cleanup

[oraluben]

Based on a wheel of pytorch, I test the speed and size of different compress level of zip.

There's some outliner in extract time, but I haven't double check them yet, let's just ignore them.

Based on size, 0->1 reduced over 50% size and 3->4 reduced >1%, all other levels have a <1% contribution. It should be reasonable to set default level (from 6) to 4, and adding another cli argument to specify compress level (to 0 or 9 if user know what they're doing) also makes sense to me.

so files only:

level	size (% of store)	zip time (s)	extract time (s)
0	1511382547(100.0%)	4.21	8.35
1	791288879(52.36%)	35.41	12.75
2	783875121(51.86%)	40.83	13.55
3	777160594(51.42%)	48.52	13.5
4	758317484(50.17%)	51.45	13.64
5	750978688(49.69%)	62.49	12.94
6	746963476(49.42%)	78.61	12.77
7	746170783(49.37%)	85.38	12.7
8	745399675(49.32%)	105.02	12.5
9	745330440(49.31%)	117.64	12.47

all files:

level	size (% of store)	zip time (s)	extract time (s)
0	2383315752(100.0%)	6.85	13.74
1	1353275864(56.78%)	58.63	20.86
2	1343694522(56.38%)	65.84	22.95
3	1335117720(56.02%)	79.87	46.13
4	1305739693(54.79%)	85.3	21.8
5	1295768731(54.37%)	102.86	22.34
6	1290671655(54.15%)	125.37	21.24
7	1289634091(54.11%)	132.69	20.91
8	1288638871(54.07%)	158.58	20.74
9	1288528808(54.06%)	176.87	21.66

[codecov]

Codecov Report

Attention: Patch coverage is 86.48649% with 10 lines in your changes missing coverage. Please review.

Project coverage is 91.48%. Comparing base (b01e842) to head (aefee5e).

Files with missing lines	Patch %	Lines
src/auditwheel/wheeltools.py	64.28%	4 Missing and 6 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #545      +/-   ##
==========================================
- Coverage   92.07%   91.48%   -0.60%     
==========================================
  Files          22       22              
  Lines        1553     1597      +44     
  Branches      285      293       +8     
==========================================
+ Hits         1430     1461      +31     
- Misses         74       81       +7     
- Partials       49       55       +6     

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[oraluben]

With the demo in PR, the time has been reduced from 3m36.515s to 2m44.353s. Concurrent grafting seems not significent, I'll see the result on our real workload later.

Only change compress level to 4: 2m53.029s

[oraluben]

Numbers:
10m59.651s (6.2.0)
10m27.363s (current version + level=6)
8m54.623s (current version)
5m14.166s (current version + level=0)

The repair part still seem potential to be optimized.

audit_orig.log
audit_fast.log

[mayeut]

@oraluben, thanks for digging into this.
I'd keep the default level for compression to 6. While the less than 1% (around .5/.6%) improvement does not seem like a big one, once you scale that to "applies to all PyPI" downloads / storage, the .5/.6% improvement applies for all downstream usage. The .1% improvement between 6 & 9 is probably not worth it (although one could re-use the argument I just used to say that it is).
Given the extract time is roughly the same for every level - except 0 obviously -, my feeling is that it's better to spend a bit more time get better compression for each of the package published (around 10,000 manylinux packages) on PyPI rather than to increase even by .5% the storage/bandwidth spent retrieving those packages (42,362,259 downloads of manylinux packages last Friday).

[mayeut]

For the " do not re-unzip wheel if possible", I'd probably move unzipping at the main_repair/main_show level not to introduce complexity with caching.