Parallelism and concurrency need different tools

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Parallelism and concurrency need different tools programming yosefk.com
via coderpath 10 years ago | archive
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  tedu 10 years ago | link
  
  Very interesting, but I think I may be more confused after reading it than I was before. The difference between parallel and concurrent was almost like this is this and that is that. If there’s a bright line between the two, I missed it.
  
  I will quibble with the claim that one cannot hope to detect race conditions without knowing what the program is trying to do (kid opens box, goes pee, comes back example). It’s actually fairly easy to detect that a result computed in one critical section is flowing into a different critical section.
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    inactive-user 10 years ago | link
    
    It’s actually fairly easy to detect that a result computed in one critical section is flowing into a different critical section.
    
    Go’s race detector does exactly this (example on a quick test program I wrote):
    
    ================== WARNING: DATA RACE Read by goroutine 5: main.readMessages() /Users/kyle/tmp/scratch/foo.go:25 0xe4 gosched0() /Users/kyle/src/go/src/pkg/runtime/proc.c:1218 0x9f Previous write by goroutine 4: main.setMessages() /Users/kyle/tmp/scratch/foo.go:16 0xe5 gosched0() /Users/kyle/src/go/src/pkg/runtime/proc.c:1218 0x9f Goroutine 5 (running) created at: main.main() /Users/kyle/tmp/scratch/foo.go:33 0x89 runtime.main() /Users/kyle/src/go/src/pkg/runtime/proc.c:182 0x91 Goroutine 4 (running) created at: main.main() /Users/kyle/tmp/scratch/foo.go:32 0x72 runtime.main() /Users/kyle/src/go/src/pkg/runtime/proc.c:182 0x91 ==================
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    tedu 10 years ago | link
    
    Hmm, having mulled this over a bit more, I’d have liked to see some discussion of sequential. If there’s one line of kids for a pile of gifts, that seems sequential to me. How, if at all, does sequential relate to concurrent. Or is it only the opposite of parallel and unrelated to concurrent?
    
    The more I think about the labelled gifts, the less I like it. Who put the labels on the gifts? Who kept the unruly kids out of the room while the labeling was done? It does look a lot nicer, but it seems he pushed a lot of the hard work off screen.

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