Android's Upcoming Resume On Reboot Feature To Make Updates Feel Faster
System updates are unavoidable in all operating systems and almost all of those require some downtime while updates are installed and the system is reconfigured properly. We are still far from the almost completely seamless and non-disruptive goal of software updates but Google has been taking steps to at least minimize the disruption updates cause. A new upcoming feature might not exactly speed things up but will make it look that way by immediately continuing the update after the phone reboots.
Rebooting, or at least restarting software, is almost a part of life for all programs. That is the biggest source of downtime for operating systems, even Linux. On Android, it's even more inconvenient since the upgrade process won't continue to completion until you unlock the phone, which is the most basic security measure after restarting the phone.
That is the same whether the phone uses the old direct way of installing updates or Android's new seamless update through A/B partitioning. The former would only actually start installing the update during the recovery stage of booting while the seamless updates install it on a second partition and simply flips the partitions at boot. Both methods still require some final operations once the phone boots up again but only after it is unlocked.
That might be a problem for updates that get installed without initial user intervention, like when it downloads and installs overnight. It won't finish the installation until the user unlocks it, which would add another few minutes to the entire process. XDA spotted a change in Android's source code pointing to a "Resume on Reboot" that won't make unlocking necessary just to finish the update while still preserving the phone's security. Hopefully, it won't be the cause of some major security exploit.
This feature would decrease the time it takes to finish the installation and give control back to the user. However, it's not something that will automatically be available for all Android phones as it has specific requirements. The Pixel 4 might be one of the first to get it and, hopefully, at least this year's roster would also be eligible.