5 ms·

New JIT optimizer in the Zing JVM

99 points by dmit 9y ago

MrBuddyCasino 9y ago
> some day someone will eventually find (and ship?) some other holy graal Was that the dis I think it was?
- deleted 9y ago
  [deleted]
- _pmf_ 9y ago
  I think it is, sir.
Thaxll 9y ago
How much it cost to run that Zing JVM per server?
- leastangle 9y ago
  To quote the FAQ: >The single license annual subscription price for Zing is $3500 USD per server, with significantly lower prices for higher volumes and longer-term subscriptions.
  - ex3ndr 9y ago
    Isn't we can just spin one more VM for each instance instead of paying 3k$?
    - StreamBright 9y ago
      Not only that but you can also use the money to buy faster CPU.
      - wbl 9y ago
        From where? They aren't making Alphas anymore, or GaN 5GHz LN2 cooled monsters. At this point SiC is the material as power dissapation has become the limiting factor.
      - hhandoko 9y ago
        Faster CPU does not eliminate GC pauses if your workload consumes a large amount of RAM. This is one of the other benefits which Zing provides.
        Chyzwar 9y ago
        You can load balance your app for 3.5k $ on additional server. By reducing load, time spend in GC will be less. Additionality by having more hardware you can use more aggressive strategy[0]. [0]http://www.cakesolutions.net/teamblogs/low-pause-gc-on-the-jvm http://www.cakesolutions.net/teamblogs/low-pause-gc-on-the-j...
        jonaf 9y ago
        I have taken Zing for a spin on 24 c3.8xl ec2 instances running Elasticsearch with 32G heaps and just under 2 billion indexed documents with millions of updates/day. The results are considerably better. If I just went up to 30 or even 50 ec2 instances on HotSpot/Openjdk, I would see no performance benefit with regard to GC. And I have performed this test. I'm not saying dont use Java because of GC, but I am saying don't overestimate the value of more efficient garbage collection in any case. Shoutout to the Azul guys, Simon, Elaine and Paul for coming on-site and watch me compile all their extensions on Amazon Linux and help me perform all the testing.
    - giltene 9y ago
      For actual end-user experience and impact of using Zing on AWS/Cassandra, check out: https://twitter.com/garryturk/status/859883566267871232 https://twitter.com/garryturk/status/859883566267871232
    - hhandoko 9y ago
      VMs adds a noticeable overhead / performance hit. Besides the benefits the new JIT provides, Zing will help you if your workload runs with / consumes over 8GB of RAM. At this point, HotSpot GC pauses [1] starts becoming noticeable (i.e. jitter). Notes: [1] - http://www.azul.com/resources/azul-technology/zing-consistent-low-latency-performance/ http://www.azul.com/resources/azul-technology/zing-consisten...
- raspasov 9y ago
  They have an AWS offering also https://aws.amazon.com/marketplace/seller-profile?id=5829a418-9742-4812-8f88-888a16300847 https://aws.amazon.com/marketplace/seller-profile?id=5829a41... . I tried it a year or so ago and my Clojure app "just worked". (I am not affiliated with Zing/Azul)
mike_hearn 9y ago
I am wary of picking an argument with Gil Tene, who certainly knows his stuff, but I wonder about the AVX2 example. The post makes it sound like Intel only contributes patches for new instruction sets to LLVM. But they are also active HotSpot contributors. For instance, here's a post from an Intel employee contributing optimisations to use AVX512: http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2016-May/022790.html http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/... I have no idea if HotSpot optimises the specific loop Gil posted, but I've seen Intel contribute a lot of upgrades to use AVX2 and AVX512, like optimised compression intrinsics. And as noted, LLVM is not really designed for Java and they had to spend three years putting in optimisations that Java-specific JITCs have had for a long time. How many contributions to LLVM will be directly applicable to Java, given that all the other contributors are focused on C++-style languages? Use of new instructions, sure, in some cases, but they aren't going to contribute intrinsics for the Java APIs. ReadyNow and C4 are very cool. Java has needed these for a long time and Zing users have been benefiting for a long time. However, Java 9 gets AOT compilation for some cases, which gives at least some of the benefit of ReadyNow (there is still warmup time, as HotSpot AOT does not cache profiles and re-profiles each time, but you get a lot closer to peak performance a lot faster). And Shenandoah is driving down pause times for huge heaps, which is where C4 shines. That said, Java 9 has not yet shipped, and Zing has. So congrats to Gil Tene and his team. The competition between Zing and HotSpot only helps.
- gopalv 9y ago
  > I have no idea if HotSpot optimises the specific loop Gil posted, I'm actually curious to see what the output assembly of LLVM is for that loop, because JDK8 does not optimize a branch in a loop. But the JVM does do a pretty decent job using ymm<n> registers if you write the loops without branches. But you end up with really obscure java code like "(((a - b) ^ (b - a)) >>> 63) ^ 1" To convert a branch into an integer.
  - flamedoge 9y ago
    you certainly can vectorize branch in a loop. Unroll loop, compute conditions in parallel, use result as a mask for conditional computation.
stephen 9y ago
I'd love the instant start-up time for Java-based tooling like IDEs/builds/etc. (assuming it's as slick as they make it sound). It would be nice if there was a developer version, e.g. not for commercial server usage, but as your local/desktop JVM installation.
- geodel 9y ago
  For that purpose I think Java 9 AOT might be sufficient. Let's see if and when Intellij/Eclipse move to that.
  - needusername 9y ago
    I think in the current form that's unlikely. It's Linux only and needs to be built on the exact same CPU. This essentially means that you have to compile on the same system as you execute.

99 points by dmit 9y ago

MrBuddyCasino 9y ago

> some day someone will eventually find (and ship?) some other holy graal Was that the dis I think it was?

deleted 9y ago
[deleted]
_pmf_ 9y ago
I think it is, sir.

Thaxll 9y ago

How much it cost to run that Zing JVM per server?

leastangle 9y ago
To quote the FAQ: >The single license annual subscription price for Zing is $3500 USD per server, with significantly lower prices for higher volumes and longer-term subscriptions.
- ex3ndr 9y ago
  Isn't we can just spin one more VM for each instance instead of paying 3k$?
  - StreamBright 9y ago
    Not only that but you can also use the money to buy faster CPU.
    - wbl 9y ago
      From where? They aren't making Alphas anymore, or GaN 5GHz LN2 cooled monsters. At this point SiC is the material as power dissapation has become the limiting factor.
    - hhandoko 9y ago
      Faster CPU does not eliminate GC pauses if your workload consumes a large amount of RAM. This is one of the other benefits which Zing provides.
      - Chyzwar 9y ago
        You can load balance your app for 3.5k $ on additional server. By reducing load, time spend in GC will be less. Additionality by having more hardware you can use more aggressive strategy[0]. [0]http://www.cakesolutions.net/teamblogs/low-pause-gc-on-the-jvm http://www.cakesolutions.net/teamblogs/low-pause-gc-on-the-j...
        jonaf 9y ago
        I have taken Zing for a spin on 24 c3.8xl ec2 instances running Elasticsearch with 32G heaps and just under 2 billion indexed documents with millions of updates/day. The results are considerably better. If I just went up to 30 or even 50 ec2 instances on HotSpot/Openjdk, I would see no performance benefit with regard to GC. And I have performed this test. I'm not saying dont use Java because of GC, but I am saying don't overestimate the value of more efficient garbage collection in any case. Shoutout to the Azul guys, Simon, Elaine and Paul for coming on-site and watch me compile all their extensions on Amazon Linux and help me perform all the testing.
  - giltene 9y ago
    For actual end-user experience and impact of using Zing on AWS/Cassandra, check out: https://twitter.com/garryturk/status/859883566267871232 https://twitter.com/garryturk/status/859883566267871232
  - hhandoko 9y ago
    VMs adds a noticeable overhead / performance hit. Besides the benefits the new JIT provides, Zing will help you if your workload runs with / consumes over 8GB of RAM. At this point, HotSpot GC pauses [1] starts becoming noticeable (i.e. jitter). Notes: [1] - http://www.azul.com/resources/azul-technology/zing-consistent-low-latency-performance/ http://www.azul.com/resources/azul-technology/zing-consisten...
raspasov 9y ago
They have an AWS offering also https://aws.amazon.com/marketplace/seller-profile?id=5829a418-9742-4812-8f88-888a16300847 https://aws.amazon.com/marketplace/seller-profile?id=5829a41... . I tried it a year or so ago and my Clojure app "just worked". (I am not affiliated with Zing/Azul)

mike_hearn 9y ago

I am wary of picking an argument with Gil Tene, who certainly knows his stuff, but I wonder about the AVX2 example. The post makes it sound like Intel only contributes patches for new instruction sets to LLVM. But they are also active HotSpot contributors. For instance, here's a post from an Intel employee contributing optimisations to use AVX512: http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2016-May/022790.html http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/... I have no idea if HotSpot optimises the specific loop Gil posted, but I've seen Intel contribute a lot of upgrades to use AVX2 and AVX512, like optimised compression intrinsics. And as noted, LLVM is not really designed for Java and they had to spend three years putting in optimisations that Java-specific JITCs have had for a long time. How many contributions to LLVM will be directly applicable to Java, given that all the other contributors are focused on C++-style languages? Use of new instructions, sure, in some cases, but they aren't going to contribute intrinsics for the Java APIs. ReadyNow and C4 are very cool. Java has needed these for a long time and Zing users have been benefiting for a long time. However, Java 9 gets AOT compilation for some cases, which gives at least some of the benefit of ReadyNow (there is still warmup time, as HotSpot AOT does not cache profiles and re-profiles each time, but you get a lot closer to peak performance a lot faster). And Shenandoah is driving down pause times for huge heaps, which is where C4 shines. That said, Java 9 has not yet shipped, and Zing has. So congrats to Gil Tene and his team. The competition between Zing and HotSpot only helps.

gopalv 9y ago
> I have no idea if HotSpot optimises the specific loop Gil posted, I'm actually curious to see what the output assembly of LLVM is for that loop, because JDK8 does not optimize a branch in a loop. But the JVM does do a pretty decent job using ymm<n> registers if you write the loops without branches. But you end up with really obscure java code like "(((a - b) ^ (b - a)) >>> 63) ^ 1" To convert a branch into an integer.
- flamedoge 9y ago
  you certainly can vectorize branch in a loop. Unroll loop, compute conditions in parallel, use result as a mask for conditional computation.

stephen 9y ago

I'd love the instant start-up time for Java-based tooling like IDEs/builds/etc. (assuming it's as slick as they make it sound). It would be nice if there was a developer version, e.g. not for commercial server usage, but as your local/desktop JVM installation.

geodel 9y ago
For that purpose I think Java 9 AOT might be sufficient. Let's see if and when Intellij/Eclipse move to that.
- needusername 9y ago
  I think in the current form that's unlikely. It's Linux only and needs to be built on the exact same CPU. This essentially means that you have to compile on the same system as you execute.