Comment by crabbone
3 years ago
This is word salad. Sorry.
What are you modeling?
The way you use "concurrency" it's indistinguishable from code without any signs of parallelism. From your "definition", concurrency is just any code. Such definitions are called "trivial" if you don't want to offend the author, and "worthless" if you are honest.
Your attempt at defining "parallelism" is even worse... You start by calling it undefined, and then proceed throwing poorly connected verbs and nouns...
Let me make it simple:
Parallel or concurrent code is code that doesn't require time interval between instructions (this is in contrast to Von Neumann model, where it's necessary to have a non-zero time span between instructions).
Here. That's it. No "but hardware", no "there are no well-defined" etc.
Your comment is subtractive from the discussion and its tone and attitude is not OK. If you came here to make no attempt to understand what people have written, even when they are explaining words, defining terms, and instead attack them and shout past them, we're better off if you didn't.
I wouldn't normally put such a fine point on it, but in this thread you've managed to make a lot of noise and calls lots of things "nonsense". If you're after emotional responses and heated discussion, that's tantamount to trolling, and you should stop.
a program which is concurrent expresses logically independent paths of execution, which can be executed one after the other, or at the same time, or any mix thereof -- it is a logical property of the program as expressed, and not necessarily exploited, or observable, when the program is run
a program which is parallel actively demonstrates multiple paths of execution during runtime -- it is a physical property of the program as executed
tl;dr: every parallel program is concurrent, not every concurrent program is parallel