Google introducedProject Mainlinein Android 10, modularizing OS components so feature and security updates could be delivered through Google Play instead of regular OTA updates. Android 10 launched with 12 supported Mainline modules, but in the latest release, that number has ballooned to37updatable modules. Here’s a look at how Project Mainline is changing inAndroid 14and beyond.
First of all, why should you care about Project Mainline updates? Well,Google published a blog post this weekrevealing that the company was able to deliver key updates to ART (the Android Runtime) through Google Play thanks to Project Mainline. These updates not only delivered new core Java language features for developers and critical security fixes, but they also yielded app start-up improvements of what Google claims isup to 30%on some devices. Since ART became a Project Mainline modulein Android 12, that means millions of devices got these improvements straight from Google.
Thanks to recent ART updates delivered through Google Play, some Android devices are seeing an up to 30% improvement in app start-up times.
Mainline is also responsible fordelivering several new features to older devices. Android 13’s Photo Picker, for example, was backported to Android 11–12L thanks to a Mainline update.
That being said, I’m sure you’re wondering whether there are any new Project Mainline modules in Android 14 you should care about. Android 14technicallyonly introduces four new Project Mainline modules, if your definition of a Project Mainline module is an APK or APEX file that’s updatable through Google Play System Updates. That’s a step down from the 11 new modulesadded in Android 11, but to be fair, it’s expected for this number to go down as more components get added to the Mainline pile.
In any case, here are the four new Mainline modules:
The list of Project Mainline modules can be found in an XML file called “module_metadata.xml”. This XML file is contained within the ModuleMetadata app, which is also responsible for providing the Google Play System Update version that you see in Settings.
Android 14 actually adds two additional APEX modules. APEX is one of two file formats supported by Project Mainline (the other being APK), but not all APEX modules are Project Mainline modules, and vice versa. Since these APEX modules aren’t updated through Google Play System Updates, I left them out of the previous list. Still, I think they’re worth bringing up:
A comparison between the /system/apex directories in Android 13 QPR3 (left) and Android 14 Beta 5 (right). The /system/apex directory contains all APEX modules that are built by default when compiling AOSP.
The changes I’m about to list are technically to modules that already exist, but I think they’re worth bringing up anyway:
Project Mainline in Android 15: What to expect
Finally, here’s a sneak peek at some of the new APEX/Project Mainline modules we may see in next year’sAndroid 15 “Vanilla Ice Cream”release:
That’s my high-level summary of what’s new in Project Mainline in Android 14 and what to expect in Android 15. There are, of course, more technical, under-the-hood changes that I haven’t brought up, as well as potentially things I missed. Once Google updates the Project Mainline documentation following the launch of Android 14, we’ll know more about what else the company added in the upcoming release.
