Magento 2 theme deployment with multiple themes/locales and multiple CPUs:

• Bug fix for Magento2 split static content deployment - multiple jobs not working with multi-language themes #4174
• Tests added? No, cannot see any existing magento2 tests
• Docs added? No, documented behaviour has not changed.

This ensures that if you set static_deploy_jobs > 1, and use split deployment, then it will minimise the no. of static:content:deploy commands issued and make best use of multiple CPUs.

NOTE: I did try multiple themes per thread but it kept getting stuck after a while - literally the progress bars not moving - possibly the same issue as #3897 . So right now it just does as many as possible with one per thread.

EXAMPLE:

set('magento_themes', [
    'Acme/brand1' => 'en_US    fr_FR   de_DE',
    'Acme/brand2' => 'en_US    fr_FR   de_DE',
    'Acme/brand3' => 'en_US    fr_FR   de_DE',
]);

set('static_content_jobs',  8);

Previously, this would've run 1 command per theme - with 3 locales that would only be using 3 jobs of a possible 8.

Now, it will calculate that brand1/2/3 all share the same locales, but it can only run brand1+2 together because that's 6 theme/locale combinations, which will make use of 6 jobs. If it also added brand3, that would be 9 theme/locale combinations, so one of the jobs would be running twice as long as the rest.

USE CASE: we have 90 themes and some have 2-4 locales. This took deployment time down from over 1 hour to ~15 mins.