As a software developer, I am trying to understand how a system could possibly work as fast and efficiently enough and operate with consistanly and flawlessly with such precision for all the ongoing actions it needs to account for in a system such as a Tesla AutoPilot (self driving car system)...
In a car driving driving 65 MPH, if a deer runs out in front of the car, it immediately makes adjustments to protect the vehicle from a crash - while having to keep up with all the other sensors requests constantly firing off at the same time for possible actions on a micro-milllisecond, without skipping a beat.
How is all of that accomplished sysinctly? And have processing reporting back to it so quickly that it almost intentaniously is able to respond (without getting backed up with requests)?
I don't know anything about Tesla code, but I have read other real time code and analysed time slips in it. One basic idea is that if you check something every millisecond you will always respond to change within a millisecond. The simplest possible real time system has a "cyclic executive" built around a repeating schedule that tells it what to do when, worked out so that in all possible cases everything that has to be dealt with is dealt with within its deadline. Traditionally you are worrying about cpu time here, but not necessarily. The system I looked at was most affected by the schedule for a serial bus called a 1553 (https://en.wikipedia.org/wiki/MIL-STD-1553)- there almost wasn't enough time to get everything transmitted and received on time.
This is a bit too simple because it doesn't cope with rare events which have to be dealt with really quickly, such as response to interrupts. Clever schemes for interrupt handling don't have as much of an advantage as you would expect, because there is often a rare worst case that makes the clever scheme underperform a cyclic executive and real time code has to work in the worst case, but in practice you do need something with interrupt handlers and high priority processes that must be run on demand and with low priority processes that can be ignored when other stuff needs to make deadlines but will be run otherwise. There are various schemes and methodologies for arguing that these more complex systems will always make their deadlines. One of the best known ones is https://en.wikipedia.org/wiki/Rate-monotonic_scheduling. See also https://en.wikipedia.org/wiki/Earliest_deadline_first_scheduling.
An open source real time operating system that has seen real life use is https://en.wikipedia.org/wiki/RTEMS.