4 ms·

This guy. Fun at parties. ;) A good point but most would think of the two the same. I know I had a hard time getting some ideas across on some research I was d

This guy. Fun at parties. ;) A good point but most would think of the two the same. I know I had a hard time getting some ideas across on some research I was doing until I separated these two concepts out. Then people started to understand.

arethuza 8y ago
Aren't concurrency and parallelism orthogonal?
- sudhirj 8y ago
  Not if they happen at the same time.
- anthony_doan 8y ago
  > Aren't concurrency and parallelism orthogonal? As in they're independent of each other? The answer would be no. Concurrency doesn't require parallelism but parallelism require concurrency. The second answer to this quora link explains it way better than I can. https://www.quora.com/What-is-the-difference-between-concurrency-and-parallelism https://www.quora.com/What-is-the-difference-between-concurr...
  - chrisseaton 8y ago
    > parallelism require concurrency I don't think it does. For example in a SIMD system there is parallelism, but no concurrency. Operations are being performed in parallel, but there is only a single program (SI..) and no concurrent tasks.
    - zzzcpan 8y ago
      Still, different pieces of hardware execute the same instruction on different data. Think of this as data concurrency if you like.
    - arethuza 8y ago
      Or the same single threaded executable running as two processes on different cores/cpus - there is parallelism but no concurrency within any of the processes?
    - bullen 8y ago
      I think you have to add "Joint" Parallel as a definition of two separate cores that collaborate on the same data at the same time - that requires concurrent memory/disc access. That Erlang can't provide BTW.
  - arethuza 8y ago
    Well, here is someone suggesting that they orthogonal: http://composition.al/blog/2014/11/24/yet-another-blog-post-about-how-parallelism-is-not-concurrency/ http://composition.al/blog/2014/11/24/yet-another-blog-post-...
  - ignoramous 8y ago
    Personally, a blog post by yosefk, the greatest CPP basher of all time [0], cleared the differences up for me: https://yosefk.com/blog/parallelism-and-concurrency-need-different-tools.html https://yosefk.com/blog/parallelism-and-concurrency-need-dif... [0] https://wiki.c2.com/?CppBashing https://wiki.c2.com/?CppBashing

arethuza 8y ago

Aren't concurrency and parallelism orthogonal?

sudhirj 8y ago
Not if they happen at the same time.
anthony_doan 8y ago
> Aren't concurrency and parallelism orthogonal? As in they're independent of each other? The answer would be no. Concurrency doesn't require parallelism but parallelism require concurrency. The second answer to this quora link explains it way better than I can. https://www.quora.com/What-is-the-difference-between-concurrency-and-parallelism https://www.quora.com/What-is-the-difference-between-concurr...
- chrisseaton 8y ago
  > parallelism require concurrency I don't think it does. For example in a SIMD system there is parallelism, but no concurrency. Operations are being performed in parallel, but there is only a single program (SI..) and no concurrent tasks.
  - zzzcpan 8y ago
    Still, different pieces of hardware execute the same instruction on different data. Think of this as data concurrency if you like.
  - arethuza 8y ago
    Or the same single threaded executable running as two processes on different cores/cpus - there is parallelism but no concurrency within any of the processes?
  - bullen 8y ago
    I think you have to add "Joint" Parallel as a definition of two separate cores that collaborate on the same data at the same time - that requires concurrent memory/disc access. That Erlang can't provide BTW.
- arethuza 8y ago
  Well, here is someone suggesting that they orthogonal: http://composition.al/blog/2014/11/24/yet-another-blog-post-about-how-parallelism-is-not-concurrency/ http://composition.al/blog/2014/11/24/yet-another-blog-post-...
- ignoramous 8y ago
  Personally, a blog post by yosefk, the greatest CPP basher of all time [0], cleared the differences up for me: https://yosefk.com/blog/parallelism-and-concurrency-need-different-tools.html https://yosefk.com/blog/parallelism-and-concurrency-need-dif... [0] https://wiki.c2.com/?CppBashing https://wiki.c2.com/?CppBashing