←back to thread

Asynchrony is not concurrency

(kristoff.it)
289 points kristoff_it | 1 comments | 18 Jul 25 19:21 UTC | HN request time: 0.24s | source
Show context
threatofrain ◴[18 Jul 25 19:57 UTC] No.44609107[source]▶
IMO the author is mixed up on his definitions for concurrency.

https://lamport.azurewebsites.net/pubs/time-clocks.pdf

replies(4): >>44609321 #>>44609563 #>>44610163 #>>44611854 #
tines ◴[18 Jul 25 20:16 UTC] No.44609321[source]▶
Can you explain more instead of linking a paper? I felt like the definitions were alright.

> Asynchrony: the possibility for tasks to run out of order and still be correct.

> Concurrency: the ability of a system to progress multiple tasks at a time, be it via parallelism or task switching.

> Parallelism: the ability of a system to execute more than one task simultaneously at the physical level.

replies(9): >>44609334 #>>44609420 #>>44609491 #>>44609531 #>>44609532 #>>44609822 #>>44609915 #>>44610273 #>>44611918 #
1. ninetyninenine ◴[18 Jul 25 21:59 UTC] No.44610273[source]▶
Doesn't multiple tasks at the same time make it simultaneous?

I think there needs to be a stricter definition here.

Concurrency is the ability of a system to chop a task into many tiny tasks. A side effect of this is that if the system chops all tasks into tiny tasks and runs them all in a sort of shuffled way it looks like parallelism.