3 ms·

> If you want cache friendly operations and predictable performance you're not going to find it in any JVM or language that has a GC. I don't know you and it's

> If you want cache friendly operations and predictable performance you're not going to find it in any JVM or language that has a GC. I don't know you and it's always dangerous to argue with people on HN due to who might be reading but I'd very strongly disagree with your above quote. Predictable performance can be obtained on a very low latency, I've seen it:) Cache friendly can be tougher and I won't argue the point as I think it will end up being a "no true Scotsman" argument where I claim Java can be cache efficient and you counter that C can do better so therefor Java isn't truly cache efficient

vvanders 10y ago
That's true, I'm very familiar with tuning Java to be cache aware. I've played around with FlatBuffers[1] in my spare time to good effect which seems to be the only sane way of doing cache aware layout in Java. That said the amount of restrictions you have makes it really painful(needing to use pre-allocated wrappers if you want to read more than intrinsic types, not being able to grow/shrink anything). There's sun.misc.Unsafe, but that isn't available on every JVM implementation. A GC is going to by nature introduce pauses if since at some point it's going to need to do work on the memory you hold. There's a set of tunable tradeoffs but it will impact latency. I guess my meta point is if throughput and latency are paramount to you then you should really consider a language suited for it. For me today that would be Rust or C++ depending on how risk-adverse the organization you're working with is. [1] https://google.github.io/flatbuffers/ https://google.github.io/flatbuffers/
- desdiv 10y ago
  >There's sun.misc.Unsafe, but that isn't available on every JVM implementation. There's also talk about the possible removal of sun.misc.Unsafe in Java 9¹. ¹ http://blog.dripstat.com/removal-of-sun-misc-unsafe-a-disaster-in-the-making/ http://blog.dripstat.com/removal-of-sun-misc-unsafe-a-disast...
  - stickfigure 10y ago
    Jeeezus... I've been writing Java since before many HNers were born, and somehow I never noticed that class. The Oracle people are right about this one. Rip it out and sterilize the wound with fire.
  - needusername 10y ago
    Oracle backpedaled from that pretty quickly.
- eggy 10y ago
  Personally, I am looking to Rust or Pony, but both are too young, and the tooling is quite there, not to mention recruitment potential. Erlang/LFE/Elixir are great for certain distributed HFT tasks, but not the core for speed and latency. The JVM is in HFT in because of sheer inertia; it has been worked on for so many years to shoehorn it in, and some smart people have made it work. The tooling is mature, and there are alternative syntaxes close to it like Kotlin that remove a lot of the noise for code review and maintenance. The JVM is the reason I stayed away from Clojure, even though I like Lisp/Scheme syntax and the semantics. Where is Clojure-clr nowadays?
- Gibbon1 10y ago
  There was an article on HN talking about the improvements go has made to their gc over the last few releases. Umm... here https://blog.twitch.tv/gos-march-to-low-latency-gc-a6fa96f06eb7#.qssombjyp https://blog.twitch.tv/gos-march-to-low-latency-gc-a6fa96f06... It sort of looks like language developers are finally getting the point that while you can easily deal with a throughput problem by just throwing faster processors, more processors, and or memory at at it, working around long gc pauses is just pain all around.

vvanders 10y ago

That's true, I'm very familiar with tuning Java to be cache aware. I've played around with FlatBuffers[1] in my spare time to good effect which seems to be the only sane way of doing cache aware layout in Java. That said the amount of restrictions you have makes it really painful(needing to use pre-allocated wrappers if you want to read more than intrinsic types, not being able to grow/shrink anything). There's sun.misc.Unsafe, but that isn't available on every JVM implementation. A GC is going to by nature introduce pauses if since at some point it's going to need to do work on the memory you hold. There's a set of tunable tradeoffs but it will impact latency. I guess my meta point is if throughput and latency are paramount to you then you should really consider a language suited for it. For me today that would be Rust or C++ depending on how risk-adverse the organization you're working with is. [1] https://google.github.io/flatbuffers/ https://google.github.io/flatbuffers/

desdiv 10y ago
>There's sun.misc.Unsafe, but that isn't available on every JVM implementation. There's also talk about the possible removal of sun.misc.Unsafe in Java 9¹. ¹ http://blog.dripstat.com/removal-of-sun-misc-unsafe-a-disaster-in-the-making/ http://blog.dripstat.com/removal-of-sun-misc-unsafe-a-disast...
- stickfigure 10y ago
  Jeeezus... I've been writing Java since before many HNers were born, and somehow I never noticed that class. The Oracle people are right about this one. Rip it out and sterilize the wound with fire.
- needusername 10y ago
  Oracle backpedaled from that pretty quickly.
eggy 10y ago
Personally, I am looking to Rust or Pony, but both are too young, and the tooling is quite there, not to mention recruitment potential. Erlang/LFE/Elixir are great for certain distributed HFT tasks, but not the core for speed and latency. The JVM is in HFT in because of sheer inertia; it has been worked on for so many years to shoehorn it in, and some smart people have made it work. The tooling is mature, and there are alternative syntaxes close to it like Kotlin that remove a lot of the noise for code review and maintenance. The JVM is the reason I stayed away from Clojure, even though I like Lisp/Scheme syntax and the semantics. Where is Clojure-clr nowadays?
Gibbon1 10y ago
There was an article on HN talking about the improvements go has made to their gc over the last few releases. Umm... here https://blog.twitch.tv/gos-march-to-low-latency-gc-a6fa96f06eb7#.qssombjyp https://blog.twitch.tv/gos-march-to-low-latency-gc-a6fa96f06... It sort of looks like language developers are finally getting the point that while you can easily deal with a throughput problem by just throwing faster processors, more processors, and or memory at at it, working around long gc pauses is just pain all around.