Thread

1. criddell · 1790278663 · focus · HN ↗

   This review seems to equate parallelism and concurrency as the same thing and they are not.

   As I understand it, the parallelism is about task execution and concurrency is about task structure. Or, as Rob Pike said:

   "Concurrency is about dealing with lots of things at once. Parallelism is about doing lots of things at once."

   He said that in his Concurrency is not Parallelism talk.

   1. mkehrt · 1790287689 · focus · HN ↗

      As other comments have pointed out, this is just not true in general usage.

      When I was a grad student studying this stuff (~20 years ago), we used "parallelism" to mean running on different cores at the same time and "concurrency" to mean preemptive multithreading on a single processor.

      1. wiml · 1790291283 · focus · HN ↗

         That's the same distinction, made in the same way, isn't it?

         1. mkehrt · 1790294925 · focus · HN ↗

            Well, we were using it to talk about things like cache invalidation and lax memory models rather than properties of algorithms.

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