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Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

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Re: Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

#11

Post by kmlx »

cassianoleal wrote: post #2

Why does Vimeo require me to verify my age in the UK to watch Robert Pike talking computer science?

In Greece (EU). Can’t play it either. I’m getting:

> This video is not rated

> Join vimeo to watch

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Re: Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

#12

Post by threatofrain »

pdpi wrote: post #7
davydm wrote: post #3

it's an interesting talk, my take being: concurrency _is_ parallelism, but for I/O. People often think of parallelism for the case of making something go faster - eg placing two computations in parallel (the definition posed in the video), OR placing two I/O operations in parallel - so this is the keyboard-vs-mouse in the OS, even when you're on one core only; this is multiple web requests in JavaScript, which does n…

> concurrency _is_ parallelism, but for I/O. Not really. They're just separate but related concepts. E.g. coroutines are a form of concurrency that doesn't have to involve any sort of I/O, you're just taking two logical processes (e.g generating a sequence and consuming it) and abstracting away how they execute relative to each other. Describing your tasks using the language of concurrency is a requirement for proces…

Concurrency is the property of a program or algorithm such that:

    - the program is decomposable into partially ordered or unordered units of execution
    - the program result remains determinant despite partial ordering
Your data-level parallelism is taking advantage of the concurrent properties of a problem.

Re: Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

#13

Post by lelandbatey »

davydm wrote: post #3

it's an interesting talk, my take being: concurrency _is_ parallelism, but for I/O. People often think of parallelism for the case of making something go faster - eg placing two computations in parallel (the definition posed in the video), OR placing two I/O operations in parallel - so this is the keyboard-vs-mouse in the OS, even when you're on one core only; this is multiple web requests in JavaScript, which does n…

No, and that's the point of the article. What you are calling parallel w/r/t IO should be called concurrency (conceptually happening at the same time by virtue of being able to interrupt and resume units of work). The reason IO APIs like you've described is concurrent but not necessqrily parallel is because there is no guarantee in the API that they both happen literally simultaneously; I could build a JS runtime that "works" for all the code written against XMLHTTPRequest (ignoring side-effects) but which under the hood only ever makes one HTTP request at a time. And because I can do that, that means JS code is living in a concurrency-only world, even though as an implementation detail most runtimes support parallel execution of those concurrent operations.

Re: Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

#17

Post by dofm »

cassianoleal wrote: post #5
davydm wrote: post #4

Earlier quoted context omitted.

because otherwise how would the queen know what you're up to all the time? :D

Since she was probably sent by God to rule, I assume he called her back upstairs upon her passing. In this case, she can just ask the big man. Funnily enough, yt-dlp has no trouble downloading it.

Side note: we do have a Queen. She's married to the King.

Re: Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

#19

Post by cassianoleal »

dofm wrote: post #17
cassianoleal wrote: post #5

Earlier quoted context omitted.

Since she was probably sent by God to rule, I assume he called her back upstairs upon her passing. In this case, she can just ask the big man. Funnily enough, yt-dlp has no trouble downloading it.

Side note: we do have a Queen. She's married to the King.

Hah! Fair point. Not sure why she would want to surveil me, but at this point...
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