57 ms·

You still have the pthreads issue. NaCL can leverage SMP in a way that single-threaded JS can't, and the idea of introducing concurrency into JS sends shivers d

You still have the pthreads issue. NaCL can leverage SMP in a way that single-threaded JS can't, and the idea of introducing concurrency into JS sends shivers down my spine.

angersock 13y ago
You mean like, Web Workers?
- deleted 13y ago
  [deleted]
- cromwellian 13y ago
  WebWorkers only support message passing, it's more like processes than threads. There's no concept of shared memory.
  - angersock 13y ago
    That model is one of the easiest and safest ways of doing concurrency of which I'm aware, unless you want to enforce immutability on shared memory records.
    - cromwellian 13y ago
      We're not talking about what's safer, were talking about NaCL vs asm.js, and the primary purpose of those is to run native C code in your browser without significant rewriting (e.g. emscripten) The target for most of this is porting C games to the Web, and many modern C games use all kinds of multithreading and blocking I/O. Game programmers are not interested in safety, they are interested in performance. Yes, message passing leads to fewer bugs. It also leaves a lot of performance on the table if you are trying to maximize usage of CPU resources on an SMP architecture.
      - angersock 13y ago
        "modern C games use all kinds of multithreading and blocking I/O." The funny thing here is that gave devs are still kind of weary of threading bugs, and blocking I/O was something that was probably earliest dealt with by the people having to stream content off of spinning plastic discs.
        cromwellian 13y ago
        It's true that gamedevs worry about this, and Tim Sweeney has even given prezos on how great functional languages would be for game programming, but the reality is, hardcore game devs crave two things from what I can tell: 1) determinism and 2) maximizing utilization of resources A VM or high level compiler abstraction, especially with GC, tends to interfere with #1, and sandboxed environments with abstract APIs for accessing hardware tend to interfere with #2. Yes, this is not to say that games won't use scripting, like Lua or UnrealScript, but those are not part of the rendering loop. Asm.js provides predictability in terms of GC, but it does not ensure predictability in terms of performance (because of differing JIT implementations), nor does it give the direct access to hardware resources one would like (e.g. SMP). I don't really see it as a target for next-gen games, regardless of the cool UnrealEngine demos. Mobile casual games maybe.
        pcwalton 13y ago
        > A VM or high level compiler abstraction, especially with GC, tends to interfere with #1, and sandboxed environments with abstract APIs for accessing hardware tend to interfere with #2. For #1, asm.js doesn't have GC, by and large (there are a couple of places where the GC gets used when interacting with Web APIs, but those are fixable and don't matter much in practice). For #2, "a sandboxed environment with abstract APIs for accessing hardware" precisely describes Pepper! > Asm.js provides predictability in terms of GC, but it does not ensure predictability in terms of performance (because of differing JIT implementations), nor does it give the direct access to hardware resources one would like (e.g. SMP). I don't understand what you mean. The performance predictability is fixed by "use asm" and AOT compilation. V8 is opposed, but your point (rightly, IMHO!) argues against that choice. If you're just arguing that there will be multiple implementations of asm.js and that's bad for predictability I don't see that being fixed with any solution outside of a browser monopoly. If PNaCl is to become a cross-browser solution, then you must be open to alternative implementations. As for threads, we can continue to evolve JavaScript so that it is supported, at least in asm.js mode. I don't see this as some fundamental obstacle.
    - ris 13y ago
      It's also one of the slowest.
  - pjmlp 13y ago
    > There's no concept of shared memory. Which is already more than proven that only leads to threading bugs.
    - jamesaguilar 13y ago
      I don't believe it has been proven to anyone's satisfaction that that is the only thing it leads to.
      - pjmlp 13y ago
        Given the amount of developers not able to write multi-threaded applications with shared memory I would say it is very well proven.
        jamesaguilar 13y ago
        "Given the amount of developers unable to write a compiler, it is well-proven that compilers lead only to bugs."
        pjmlp 13y ago
        Where can I find a bug free one?
        jamesaguilar 13y ago
        I think the proper question under the formulation you provided is, "Where can I find one that does anything other than produce bugs," since you asserted that bugs are the only result. To which the answer is: any of them.
        riffraff 13y ago
        the argued keyword in your previous comment is "only".
        deleted 13y ago
        [deleted]
  - deleted 13y ago
    [deleted]
- blueblob 13y ago
  Perhaps locking the DOM is a good trait if you can communicate between the main thread and the webworkers then you can request that the main thread changes the DOM and synchronize, without this you might get unexpected behavior anyways?
jlongster 13y ago
There's already a lot of good progress with introducing parallelism in JavaScript. See http://wiki.ecmascript.org/doku.php?id=strawman:data_parallelism http://wiki.ecmascript.org/doku.php?id=strawman:data_paralle...
pcwalton 13y ago
> NaCL can leverage SMP in a way that single-threaded JS can't, and the idea of introducing concurrency into JS sends shivers down my spine. I agree that we don't want to break the single-threaded JS model. But we have options, the easiest of which is to restrict shared mutable state to ArrayBuffers and asm.js, or asm.js-like code.

You still have the pthreads issue. NaCL can leverage SMP in a way that single-threaded JS can't, and the idea of introducing concurrency into JS sends shivers down my spine.

angersock 13y ago

You mean like, Web Workers?

deleted 13y ago
[deleted]
cromwellian 13y ago
WebWorkers only support message passing, it's more like processes than threads. There's no concept of shared memory.
- angersock 13y ago
  That model is one of the easiest and safest ways of doing concurrency of which I'm aware, unless you want to enforce immutability on shared memory records.
  - cromwellian 13y ago
    We're not talking about what's safer, were talking about NaCL vs asm.js, and the primary purpose of those is to run native C code in your browser without significant rewriting (e.g. emscripten) The target for most of this is porting C games to the Web, and many modern C games use all kinds of multithreading and blocking I/O. Game programmers are not interested in safety, they are interested in performance. Yes, message passing leads to fewer bugs. It also leaves a lot of performance on the table if you are trying to maximize usage of CPU resources on an SMP architecture.
    - angersock 13y ago
      "modern C games use all kinds of multithreading and blocking I/O." The funny thing here is that gave devs are still kind of weary of threading bugs, and blocking I/O was something that was probably earliest dealt with by the people having to stream content off of spinning plastic discs.
      - cromwellian 13y ago
        It's true that gamedevs worry about this, and Tim Sweeney has even given prezos on how great functional languages would be for game programming, but the reality is, hardcore game devs crave two things from what I can tell: 1) determinism and 2) maximizing utilization of resources A VM or high level compiler abstraction, especially with GC, tends to interfere with #1, and sandboxed environments with abstract APIs for accessing hardware tend to interfere with #2. Yes, this is not to say that games won't use scripting, like Lua or UnrealScript, but those are not part of the rendering loop. Asm.js provides predictability in terms of GC, but it does not ensure predictability in terms of performance (because of differing JIT implementations), nor does it give the direct access to hardware resources one would like (e.g. SMP). I don't really see it as a target for next-gen games, regardless of the cool UnrealEngine demos. Mobile casual games maybe.
        pcwalton 13y ago
        > A VM or high level compiler abstraction, especially with GC, tends to interfere with #1, and sandboxed environments with abstract APIs for accessing hardware tend to interfere with #2. For #1, asm.js doesn't have GC, by and large (there are a couple of places where the GC gets used when interacting with Web APIs, but those are fixable and don't matter much in practice). For #2, "a sandboxed environment with abstract APIs for accessing hardware" precisely describes Pepper! > Asm.js provides predictability in terms of GC, but it does not ensure predictability in terms of performance (because of differing JIT implementations), nor does it give the direct access to hardware resources one would like (e.g. SMP). I don't understand what you mean. The performance predictability is fixed by "use asm" and AOT compilation. V8 is opposed, but your point (rightly, IMHO!) argues against that choice. If you're just arguing that there will be multiple implementations of asm.js and that's bad for predictability I don't see that being fixed with any solution outside of a browser monopoly. If PNaCl is to become a cross-browser solution, then you must be open to alternative implementations. As for threads, we can continue to evolve JavaScript so that it is supported, at least in asm.js mode. I don't see this as some fundamental obstacle.
  - ris 13y ago
    It's also one of the slowest.
- pjmlp 13y ago
  > There's no concept of shared memory. Which is already more than proven that only leads to threading bugs.
  - jamesaguilar 13y ago
    I don't believe it has been proven to anyone's satisfaction that that is the only thing it leads to.
    - pjmlp 13y ago
      Given the amount of developers not able to write multi-threaded applications with shared memory I would say it is very well proven.
      - jamesaguilar 13y ago
        "Given the amount of developers unable to write a compiler, it is well-proven that compilers lead only to bugs."
        pjmlp 13y ago
        Where can I find a bug free one?
        jamesaguilar 13y ago
        I think the proper question under the formulation you provided is, "Where can I find one that does anything other than produce bugs," since you asserted that bugs are the only result. To which the answer is: any of them.
      - riffraff 13y ago
        the argued keyword in your previous comment is "only".
      - deleted 13y ago
        [deleted]
- deleted 13y ago
  [deleted]
blueblob 13y ago
Perhaps locking the DOM is a good trait if you can communicate between the main thread and the webworkers then you can request that the main thread changes the DOM and synchronize, without this you might get unexpected behavior anyways?

jlongster 13y ago

There's already a lot of good progress with introducing parallelism in JavaScript. See http://wiki.ecmascript.org/doku.php?id=strawman:data_parallelism http://wiki.ecmascript.org/doku.php?id=strawman:data_paralle...

pcwalton 13y ago

> NaCL can leverage SMP in a way that single-threaded JS can't, and the idea of introducing concurrency into JS sends shivers down my spine. I agree that we don't want to break the single-threaded JS model. But we have options, the easiest of which is to restrict shared mutable state to ArrayBuffers and asm.js, or asm.js-like code.