Ask HN: On Rob Pike's Concurrency is not Parallelism? • Hacker News Board

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#41

Post by slantedview » Mon, Jul 30, 2012, 4:08 PM UTC

ryah wrote: post #37

KirinDave wrote: post #33

Earlier quoted context omitted.

You know, ryah; I like your work ethic, I like your enthusiasm, I think you're a cool guy and it's great your project has so much traction. But you say things like this and it worries me. Because a lot of people look up to you and either you said this because you feel defensive about your project or you said it because you genuinely don't understand the cases we're talking about here. And this is a problem because a…

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

Wait, so, you wrote off the JVM because of XML and IDEs? Really?

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#42

Post by rvirding » Mon, Jul 30, 2012, 4:12 PM UTC

ryah wrote: post #37

KirinDave wrote: post #33

Earlier quoted context omitted.

You know, ryah; I like your work ethic, I like your enthusiasm, I think you're a cool guy and it's great your project has so much traction. But you say things like this and it worries me. Because a lot of people look up to you and either you said this because you feel defensive about your project or you said it because you genuinely don't understand the cases we're talking about here. And this is a problem because a…

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

"I love Erlang but I cannot get the past the syntax."

I cannot understand this hangup about syntax. Syntax is the easiest thing to learn with a new language, you just look it up. It's the semantics and usage where the real problems are.

Erlang doesn't have static typing, it is dynamically typed. It has always been dynamically typed.

And however you look at it doing highly concurrent systems with processes is much easier. And who says that processes imply "parallel access to shared memory"? Quite the opposite actually.

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#43

Post by gar1t » Mon, Jul 30, 2012, 4:21 PM UTC

ryah wrote: post #37

KirinDave wrote: post #33

Earlier quoted context omitted.

You know, ryah; I like your work ethic, I like your enthusiasm, I think you're a cool guy and it's great your project has so much traction. But you say things like this and it worries me. Because a lot of people look up to you and either you said this because you feel defensive about your project or you said it because you genuinely don't understand the cases we're talking about here. And this is a problem because a…

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

Erlang's syntax is one of those things that's just too hard to get past. Along with the other obstacles, it makes Erlang nearly impossible to attain!

http://www.youtube.com/watch?v=zY-IueSMAPc

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#44

Post by rvirding » Mon, Jul 30, 2012, 4:35 PM UTC

gar1t wrote: post #43

ryah wrote: post #37

Earlier quoted context omitted.

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

Erlang's syntax is one of those things that's just too hard to get past. Along with the other obstacles, it makes Erlang nearly impossible to attain! http://www.youtube.com/watch?v=zY-IueSMAPc

Beware of "Kenneth the Swede"! Just stay on the straight and narrow and you will reach the Celestial City.

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#45

Post by ches » Mon, Jul 30, 2012, 5:06 PM UTC

rvirding wrote: post #42

ryah wrote: post #37

Earlier quoted context omitted.

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

"I love Erlang but I cannot get the past the syntax." I cannot understand this hangup about syntax. Syntax is the easiest thing to learn with a new language, you just look it up. It's the semantics and usage where the real problems are. Erlang doesn't have static typing, it is dynamically typed. It has always been dynamically typed. And however you look at it doing highly concurrent systems with processes is much eas…

FWIW I believe "Maybe you don't care about Erlang's syntax or static typing" was referring to his earlier mention of Go as statically typed. A comma would have improved the clarity :-)

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#46

Post by tholschuh » Mon, Jul 30, 2012, 6:22 PM UTC

ryah wrote: post #37

KirinDave wrote: post #33

Earlier quoted context omitted.

You know, ryah; I like your work ethic, I like your enthusiasm, I think you're a cool guy and it's great your project has so much traction. But you say things like this and it worries me. Because a lot of people look up to you and either you said this because you feel defensive about your project or you said it because you genuinely don't understand the cases we're talking about here. And this is a problem because a…

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

If you like Erlang but cannot get past its syntax you might want to give Elixir a try.

http://elixir-lang.org/

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#47

Post by rvirding » Mon, Jul 30, 2012, 6:26 PM UTC

arebop wrote: post #6

I think his point is that although people are often interested in parallel behavior, they should really focus more on concurrent design to avoid/remove the dependencies that ultimately limit parallelism. Slide 19 mentions automatic parallelization, but his point is that developers should think more about concurrency and not that Go will automatically maximally parallelize concurrent programs.

Yes. For the underlying system to be able to detect and run in parallel you need the concurrency. Without concurrency your application will be run sequentially.

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#48

Post by bascule » Mon, Jul 30, 2012, 6:47 PM UTC

ryah wrote: post #27

aphyr wrote: post #25

Earlier quoted context omitted.

It's parallel in the same sense that any POSIX program is: Node pays a higher cost than real parallel VMs in serialization across IPC boundaries, not being able to take advantage of atomic CPU operations on shared data structures, etc. At least it did last time I looked. Maybe they're doing some shm-style magic/semaphore stuff now. Still going to pay the context switch cost.

it's all serialization - but that's not a bottleneck for most web servers. i'd love to hear your context-switching free multicore solution. this is the sanest and most pragmatic way server a web server from multiple threads

It's more than that. Several processes with small, independently garbage collected heaps are not as efficient as a single process with a large heap, parallel threads, and a modern concurrent GC (e.g. the JVM's ConcurrentMarkSweep GC)

In addition to that, processes severely inhibit the usefulness of in-process caches. Where threads would allow a single VM to have a large in-process cache, processes generally prevent such collaboration and mean you can only have multiple, duplicated, smaller in-process caches. (Yes, you could use SysV shared memory, but that's also fraught with issues)

The same goes for any type of service you would like to run inside a particular web server that could otherwise be shared among multiple threads.

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#49

Post by canweriotnow » Mon, Jul 30, 2012, 7:11 PM UTC

aeden wrote: post #40

ryah wrote: post #37

Earlier quoted context omitted.

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

"I love Erlang but I cannot get the past the syntax." I also thought this. For some reason though the more I use it the more I am coming around to its syntax. There are lots of gotchas when compared with other popular languages, but still its syntax has grown on me recently. At the opposite end of the syntactic spectrum is Lisp. The more I use Clojure the more I am loving it as well. "The future of server programming…

"The future of server programming does not have parallel access to shared memory."

What about STM in Clojure? It's technically parallel access to shared memory, but the transactional nature obviates the need for mutexes and all the crap that makes shared memory a pain in the ass.

Re: Ask HN: On Rob Pike's Concurrency is not Parallelism?

#50

Post by zem » Mon, Jul 30, 2012, 7:42 PM UTC

rvirding wrote: post #42

ryah wrote: post #37

Earlier quoted context omitted.

Node is popular because it allows normal people to do high concurrency servers. It's not the fastest or leanest or even very well put together - but it makes good trade offs in terms of cognitive overhead, simplicity of implementation, and performance. I have a lot of problems with Node myself - but the single event loop per process is not one of them. I think that is a good programming model for app developers. I lo…

"I love Erlang but I cannot get the past the syntax." I cannot understand this hangup about syntax. Syntax is the easiest thing to learn with a new language, you just look it up. It's the semantics and usage where the real problems are. Erlang doesn't have static typing, it is dynamically typed. It has always been dynamically typed. And however you look at it doing highly concurrent systems with processes is much eas…

syntax is the user interface of the language. it is one of the parts you have to deal with on a constant basis, both writing and reading code. i can well see how an unpleasant syntax can be a constant, grating annoyance when dealing with a language. (i happen to really like erlang's syntax, but it definitely has very different aesthetics from javascript's)