piwheels - camjam

piwheels talk given at camjam October 2017

Transcript

1. piwheels: building a faster Python package repository for Raspberry Pi users Ben Nuttall Raspberry Pi Foundation UK Charity 1129409
2. Ben Nuttall • Raspberry Pi Community Manager • Columnist on opensource.com • github.com/bennuttall • twitter.com/ben_nuttall • ben@raspberrypi.org
3. Space
4. Astro Pi
5. Dave • Dave: I need your help. Can we install these libraries in space? • Me: I think so, if we build wheels of them.
6. pip wheel numpy
7. PyPI • Python package repository hosted at pypi.python.org • Install packages with “pip install” • Packages can be implemented in Python or C • Packages implemented in C require building – This can take a long time
8. Python wheels • Wheels are built distributions, and can be uploaded to PyPI alongside source distributions • This saves users from building themselves • Wheels are architecture-specific – e.g. win32, win64, macosx, linux32, linux64 • A recent addition allowed “manylinux” wheels to be uploaded • Raspberry Pi is not the “manylinux” architecture, it’s ARM
9. ARM wheels • Technically... – Pi 3 is ARMv8 – Pi 2 is ARMv7 – Pi 1 / Zero are ARMv6 • But... – Wheels built on Pi 2/3 are tagged “armv7l” – Wheels built on Pi 1 / Zero are tagged “armv6l” • And… – They are actually ARMv6 wheels, and they’re all the same • So… – A wheel built on a Pi 3 will work on a Pi 2, as is – A wheel built on a Pi 3 will work on a Pi 1 / Zero (if renamed to “armv6l”)
10. pip install <package>
11. Which type of x86/x86_64 are you?
12. ...I have them all
13. Actually I’m linux_armv7l
14. What? I’ve never heard of it. Here’s the source, build it yourself! • PyPI doesn’t support uploading ARM wheels :( • “pip install numpy” takes: – ~20 mins on Pi 3 (1.2GHz quad-core) – ~2.5 hours on Pi 1 (700MHz single-core)
15. Fine! I’ll build my own package repository... • cd Projects • mkdir piwheels • cd piwheels • git init
16. piwheels • I could build everything on PyPI and host my own repository – “pip wheel numpy” works on a Pi – You can distribute the wheel and it’s a super fast install • Can I host my own package repository? – Apparently, yes! – At minimum, an Apache directory listing will do the trick
17. piwheels v1 • Pi 3 in my living room • Build the latest version of every package (106k packages at the time) • Log output into postgres database • Host a package repository on the same Pi
18. piwheels v1: the results • It took 10 days to complete the build run • 76% build success rate • Repository (was) live at piwheels.bennuttall.com • “pip install numpy ­i http://piwheels.bennuttall.com” works and takes 6 seconds :) • Proof of concept: it works, it’s probably useful
19. Planning piwheels v2 • Build every version of every package • Keep up with new releases automatically • Host a package repository as before • Create a test suite • Provide installation instructions & developer documentation so people can contribute
20. Planning piwheels v2 • Now 113k packages on PyPI • But now I’m building every version of every package • 750k package versions to build • At the previous rate, this will take 70 days on one Pi… – Maybe I could use … more than one Pi?
21. Mythic Beasts: Pi in the cloud
22. There is no Raspberry Pi cloud...
23. Pete
25. piwheels v2 • One Pi to start • Left it running for a couple of weeks: – Actually running slower than before due to NFS – New estimate: 100 days
26. Lightning talk at EuroPython
27. Why don’t you just cross-compile? • It’s not all about speed • Reliability • Compatability • Familiarity • Ease of use • I can scale up Pis easily • Eating my own dog food
30. ALL the cloud Pis
31. Adding more Pis • Provisioned a second Pi – No web server or database – Connected to the database on first Pi – rsync files to first Pi • Provisioned a third Pi • Installed “terminator” • Provisioned Pis 4 and 5 • This is easy. I’ll be done in no time!
33. It didn’t scale • Output on 3 Pis was about the same as the output on 1 Pi • The database was getting hammered
34. Dave Jones • Author of picamera • Co-author of GPIO Zero • Self-professed SQL know-it- all • We’ve worked together on open source projects a lot
35. Make it scale! • Pull request: – Query optimisations – Queuing system with zeromq • Re-deployed the code • Original Pi is now “master” running database and web server only • Other Pis are now “builders” using master’s database and rsync- ing files to master
36. It worked! Keep going!
37. 20 Raspberry Pis • ~3k packages per hour • ~72k per day (10%) • Now also logging which Pi built each package • Pis seem to be holding up • Dropped rsync in favour of sshfs • It’s going well! I’ll be done in no time!
38. People do stupid things • Random files created in my home directory • Random stuff appended to my .bashrc • Some people run “git clone” in their setup.py • Inadvertently importing numpy
39. The results • Total packages processed: 113, 649 • Package versions built: 570, 648 / 752, 817 (76%) • Total cumulative time spent building: 156 days, 18 hours (including duplicates) – In real time this was 26 days: • 16 days with 1 Pi building • 10 days with up to 19 Pis building • 250GB disk space used by wheels
40. Reasons for failure
41. The results (round 2) • Discount “no release” versions • Install key missing dependencies • Total packages: 100, 802 / 117, 444 (86%) • Package versions: 586, 266 / 703, 571 (83%)
42. Reasons for failure (round 2)
43. It’s done! • Scaled down to 5 Pis to keep up with new releases • Thanks, Pete! You can have them back now.
44. Running piwheels as a real service • Continue to build all new releases on a small number of buider Pis • Added SSL to web domain • Provide ARMv6 wheels for Pi 1 / Zero • Build mechanism for triggering builds for multiple Python versions (3.4, 3.5, 3.6, 2.7) • Added the piwheels server to pip config in Raspbian – Users get wheels for free without needing to know about it
45. Does it work? • Raspbian Stretch: – pip configured to use piwheels – But… we haven’t rebuilt packages for Stretch yet (Python 3.5) – Pure Python packages are available, but big C ones like numpy aren’t (yet) • Raspbian Jessie: – Manually configure pip to use piwheels – All packages are built for Jessie (Python 3.4)
46. www.piwheels.hostedpi.com
47. piwheels: building a faster Python package repository for Raspberry Pi users Ben Nuttall Raspberry Pi Foundation UK Charity 1129409