= Concurrency
== Concurrency versus parallelism

https://go.dev/blog/waza-talk

“Concurrency is about ordering of computations and parallelism is about the mode of operation”
“Concurrency is a way of organizing code and parallelism is a resource”

== Process-level threads

fibers == user-mode threads == green threads == lightweight threads tasks ==  ~ goroutines
  OS threads → preemptive
  async → cooperative
    → between yielding points, you will execute uninterrupted
      ⇒ long time between yielding points? no progress!
    → simpler implementation

Questions to evaluate the concurrency concept:

• is it cooperative? is it preemptive?
• can arguments be passed to the function/routine?
• what information is shared between parent-child?
• If the child dies (exception), does the parent die?
• Does the runtime wait for all children to terminate before terminating itself?
• does it support cancellation (always cooperatively)?
• how does one wait for all concurrent units to terminate (“joining”)?

https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/