Design principles of otavia
Object-oriented programming is a very useful programming paradigm, and while the original object-oriented idea was somewhat similar to the Actor model, where an object is equivalent to an Actor, modern implementations of object-oriented in the major programming languages have degraded it to a way of organizing and encapsulating the code, since the cost of calling methods directly is much less than message passing. This is wonderful in the single-threaded case, where everything is organized.
But the crisis came with multithreading and multiple CPU cores: multithreading is like a herd of savage bulls rampaging through a fragile jungle of objects! Instead of having a single path of execution, programs are now controlled by a well-organized set of objects. Instead, you need to care carefully whether each object will be accessed by more than one thread at the same time, and you need to double-check your program’s concurrency safety. But it’s not easy to do. Especially for a software system of enormous size, you don’t know how many threads are rushing through your jungle of objects, so you need to go out and simulate every thread with a human brain, track their paths, and then figure out which objects should need to deal with concurrency safety. Imagine tracking down this herd of savage bulls in the jungle, meticulously checking one by one which grasses they’ve stepped on! God, it’s maddening to think about. All this work was already exhausting, but there was an even more serious problem: these bulls would suddenly come to a standstill when they stepped on certain grass! They are blocked and thus suspended, and this reduces the system’s CPU utilization, which in turn may lead to the launching of more threads, with more and more concurrent contention, until the system crashes under a concurrency problem that is not rigorously examined!
Happily, new technologies have emerged to solve these problems. The most popular technical solutions are coroutine and JVM virtual threads. However, in our opinion, these techniques are effective in alleviating the problem of low CPU utilization due to suspended threads, but they do not alleviate the problem of having to carefully design our objects due to concurrency competition.
The main reason the problem has gotten so bad we believe is that the current mainstream programming languages and object-oriented programming paradigms are missing some of their key features! That is, the lack of organization of concurrency and the lack of organization of execution flow! Concurrency and execution flow are currently coupled with objects, which was not a problem in early single-threaded environments, but becomes very serious in multi-threaded, multi-CPU environments!
Organizing concurrency and execution flow is where the Actor model excels! With the advent of Scala 3, we saw the possibility of designing an Actor programming tool that was more in line with object-oriented thinking. So, after a long period of conceptualization, I designed otavia and its associated toolkit. The goal is to explore a simpler and safer programming paradigm to meet the current challenges. Also hope to open up a new idea to provide everyone to promote the development of programming tools!
We believe that a better programming hierarchy would look like the following, and the design of otavia follows this hierarchy
System > Process > Threads > Virtual Threads/Stacked coroutines > Actor > Objects > Functions
In this hierarchical design, the Actor is the end point of concurrency, i.e., the Actor and its subsequent parts should all run single-threaded! Actors communicate with each other by sending messages, and multiple messages are processed one by one in the Actor’s mailbox in a single-threaded fashion.The logic inside the Actor can be either object-oriented or functional, or even a combination of them, as in Scala! Now everything is simple again and you can boldly use objects without worrying about that wild herd of bulls!
‘otavia’ is a very interesting project, which is currently in the incubation stage. If you are interested, any contribution from you is warmly welcome! We would also love to hear your suggestions or criticisms about the project. All your comments will ultimately help us to improve the quality of the project! You can also give a like to the project to encourage the contributors to the project! You can also give the project a star to encourage contributors!