Armstrong thesis - Chap. 2

Chapter 2 of Armstrong's thesis is describing how to build fault-tolerant systems with very demanding requirements. The solution is to implement modules as isolated processes with no sharing of resources, message passing communication to achieve concurrency and error detection, and a fail-fast policy when a process crashes; similar to how processes in operating systems work. But it seems that in order to achieve all of this, you need the right hardware, the right OS, and a programming language that allows developers to implement fault-tolerant systems that support all of these requirements. They're asking for a lot from a system so I'm curious to understand the details to their approach. They made several references to Tandem computers so I wonder if their approach is similar to providing redundancy at every level.

The chapters mentions that programming languages can't be used for building robust systems because they're not able to "isolate software components from each other". Well, couldn't I just simply create new processes in C++ or Java to create this isolation? Or maybe a language such as Erlang provides the ability to develop an application where the underlying system in which it runs will separate different modules into processes (haven't read Chap. 3 of the thesis yet). If this is case, then it's true C++ nor Java have frameworks that separate their modules into separate processes. At least none that I know about.

I didn't understand how adding more processes could not affect the original system. I mean, everyone knows that adding more processes can consume a lot of CPU and memory resources. Unless they mean that sufficient hardware should exist for supporting 100,000 processes! Also, how are object-oriented languages not true asynchronous messages. Many of them provide the ability to specify a call-back so that programs don't block on an RPC call. What does a COPL have that an OO language doesn't with respect to this?

Erlang's support for hot code loading is one I've never heard about but I can see its enormous potential if you can combine it with an AOM system. Not only would you be able to keep your system running during upgrades but this could realize an extremely flexible system.