Parallel compiling: arduino-builder will leverage your multi core pc

[copercini]

If -jobs X param is specified and X is greater than 0, arduino-builder won't spawn more than X processes. Fixes #17

• Rebased from Federico Fissore branch 0a3d888
• Add HumanTagsLogger compatibility
• Remove an if which suppress some GCC error messages here: 0a3d888#diff-8f074e2b3fc911dbe8255891fc1a9b13R96

[copercini]

Compilation time benchmarks (Based on Travis CI builds )

[facchinm]

@ArduinoBot build this please

[ArduinoBot]

✅ Build completed.

⬇️ Build URL: http://downloads.arduino.cc/PR/arduino-builder/arduino-builder-242.zip

ℹ️ To test this build:

1. Replace arduino-builder binary (you can find it where you installed the IDE) with the provided one

[ArduinoBot]

✅ Build completed.

⬇️ Build URL: http://downloads.arduino.cc/PR/arduino-builder/arduino-builder-242.zip

ℹ️ To test this build:

1. Replace arduino-builder binary (you can find it where you installed the IDE) with the provided one

[matthijskooijman]

@copercini, I couldn't manage to reproduce the slowness of the PR236 build (see #236 (comment)). Any chance that was just a measurement error on your side (system under load perhaps)? Could you see if you can reproduce this slowness again?

[copercini]

@matthijskooijman The data used in the table comes from this build: https://travis-ci.org/arduino/arduino-builder/builds/243798460
In the new builds of #236 like https://travis-ci.org/arduino/arduino-builder/builds/309526510 the compilation time is similar to others PRs, so everything looks normal

So yes, probably the slowness comes from something in Travis CI just at this time and your PR is fine

[matthijskooijman]

Thanks for checking!

[kubark42]

This seems useful. Especially on Windows, where Arduino seems to build more slowly on a 2018 Surface Book 2 than a 2014 Macbook Pro. @copercini was there a blocker?

[cmaglie]

This one has been manually merged.

[PaulStoffregen]

Any chance for a 1.8.6 release with this feature?

I've been using 1.8.5 with 1.9's builder and preprocessor, and the new preprocessor rule added to 1.8.5's platform.txt. It's really awesome for larger projects with a lot of code!

I'm sure much of the Arduino community would love a near-term stable 1.8.6 release with this feature....