17 ms·

Prerequisite: You have the stomach for a relatively immature language Re Erlang/Elixir the number 1 selling point would be if you need performance that you ca

• mafribe 10y ago
  Where does Pony's performance vis-a-vis Erlang/BEAM come from? The absence of dynamic typing? Better scheduler?
  • spooneybarger 10y ago
    There are a number of areas: Most message passing on BEAM is done via copying. Pony can share the memory directly because the compiler enforces safe sharing via deny capabilities. You can only send 3 basic types to another actor: iso -> mutable memory that you have the sole reference to val -> immutable reference. you can read but you can't write tag -> an opaque reference. good for sending messages to actors or doing identity comparisons The type system certainly helps as well. It allows us to give LLVM hints on optimizations it can make. The type system also helps because we can do "dangerous but fast" things safely because we can prove they are safe in this instance. Compiling to native code via LLVM is another area for performance wins. That said, Erlang has over 20 years of rock solid production usage behind it and that unto itself is a quite a selling point. At this point in time, I'd suggest Pony to Erlang/Elixir users if they need more performance, otherwise, I'd stick with Erlang for now.
    • steveklabnik 10y ago
      > The type system also helps because we can do "dangerous but fast" > things safely because we can prove they are safe in this instance. This is an area of some static type systems that I'm really interested in; it feels counter-intuitive at first. You'd imagine that flexibility is what lets you do the things you need to do to go fast, but in many cases, restrictions actually are. Cool stuff.
      • infinite8s 10y ago
        Yeah, see the lack of aliasing in fortran as an example of a restriction that allows the compiler to generate optimal code.
      • mintplant 10y ago
        Absolutely. In modern JavaScript engines, for example, dynamic typing makes something as basic as |foo.bar = 7| extremely complicated internally. In SpiderMonkey, |foo| could be a native object with |bar| in some varying location on a fixed or dynamic slot, or it could involve a proxy, a setter, unboxed or unboxed expando object, DOM or cross-compartment wrapper... To make the whole thing efficient, a particular property access could go through engine code, specialized JIT-generated native code after enough type information has been collected, or one of three inline cache systems, which generate multiple native code stubs |switch|ed on checks based on previous (slower) executions. A given get or set could even pass through more than one of the above, if too many checks fail and bailouts are required. And |bar| could be located directly on |foo| or on some object in |foo|'s prototype chain, requiring on-the-fly verification of additional invariants to ensure correctness. Static typing would mean the engine can know for sure what |foo| is and where to look for |bar|, allowing faster, guaranteed-correct code to be emitted ahead of time. Dynamic typing makes it harder to offer speed, correctness, security, and good memory usage all at once.
      • vanderZwan 10y ago
        > You'd imagine that flexibility is what lets you do the things you need to do to go fast, but in many cases, restrictions actually are. Aren't you mixing up flexibility for the programmer with flexibility for the compiler? The more restrictions the programmer has, the more flexibility the compiler has to change instructions and still produce the same results.
        • steveklabnik 10y ago
          Sure. But I think a lot of people do, and it colors the way we look at programming languages.
        • PeCaN 10y ago
    • mafribe 10y ago
      Thanks, that's interesting. Linear types are useful, undoubtably because they can reduce copying. What kind of scheduling does Pony use?
      • 59nadir 10y ago
        As per http://tutorial.ponylang.org/gotchas/scheduling.html http://tutorial.ponylang.org/gotchas/scheduling.html it's a cooperative scheduler, which is disappointing.
        • mafribe 10y ago
          That means BEAM - Pony is not a fair comparison, because cooperative schedulers solve a much simpler algorithmic problem.
  • rurban 10y ago
    pony is compiled to native code, and to highly optimized code. beam is just interpreted. even if most of the time the code has to wait, it has to wait much less. that's why pony can beat C++ with OpenMP in comparable tasks. It's garbage collector is superior, having to do much less work than in beam. The data workload for each thread is much smaller. objects are tiny, messages are mostly referenced (shared) and not copied. erlang does more. it already supports distributed actors, so there's a little overhead also.
    • PeCaN 10y ago
      Curious, how is Pony's GC superior to Erlang? Erlang's GC is already pretty quick (since the heaps are very small).
      • doublec 10y ago
        There's a thread here from a previous discussion: https://news.ycombinator.com/item?id=9483071 https://news.ycombinator.com/item?id=9483071 One nice thing about the Pony GC is it can GC actors that are waiting for messages but will never receive one. In some other languages I've used I end up with processes idling in a receive on channel living forever but never able to exit because nothing is going to put a message in the channel.