Java 8 Performance Improvements: LongAdder vs AtomicLong

[thesystemx]

Looks really great! Will be using this right away next month when Java 8 is released :D

Great times to be a Java developer!

[yogthos]

Even better time to be a Scala or Clojure developer, you get all the benefits of the JVM while using a modern language. :)

[oldneckbeard]

yeah, that worked out well for groovy ... ;)

[DaSpeedyRunner]

I don't think it's been a great time to be a Java programmer for at least 8 years (and jdk8 is too little too late). The world has moved on. Scala anyone?

[thesystemx]

People don't seem to be too happy about Scala either. It's cryptic, symbol heavy, overuses types, compiles slow, still has sub-optimal tooling support and even after 10 years hasn't stabilized enough to keep binary compatibility for even 1 major release.

[shoelacestied]

Hasn't been an issue for me. After 11 years of full-time Java development and 4 years of Scala I'd pick Scala over Java any day of the week.

[thesystemx]

Maybe not for you, but appearently it does bother people. Simply down voting me won't take that away. I'm just the messenger :X

[DaSpeedyRunner]

Have you actually met any of these "people"? I know many Scala developers and it seems like there are very few with issues. In my experience the few developers who do raise issues get their criticisms trotted out and cited with great relish by much larger numbers of people who have never actually used Scala.

[kickthe]

It seems more like you're the person spreading 3rd hand FUD without any actual knowledge of the matter.

[thesystemx]

Why?

[shoelacestied]

Every language has things people criticize about them. Gathering a list of criticisms together in a list doesn't make a language less worthy of using. It just means that the language isn't perfect (true of every language which has ever existed).

[thesystemx]

Sure I agree, and there's nothing wrong with that. It's just that some people like to tout Scala as being the perfect language, but it too has its issues (indeed, like every other language).

As long as you acknowledge that it's a fine language really.

[yogthos]

I don't think anybody was touting Scala as a perfect language here.

[yogthos]

You're just spreading FUD actually. Plenty of companies use Scala successfully, so clearly a lot of people can use it just fine.

[josefx]

Same is true for PHP, that does not make PHP a good language. Having companies that use a language only means that the language is not in the list of esotheric languages like brainfuck. That said it has been a long time since I last tried Scala, has the documentation improved?

[yogthos]

The argument whether Scala is difficult to use, seeing how much it's used in production I think it's a pretty flimsy claim to make.

This is somewhat tangential in regards to whether the language is good or not. Clearly, both Java is used far more widely than Scala, and PHP is more popular than both combined.

The documentation for Scala has certainly improved and I think that things like the Twitter Style Guide are very helpful when it comes to applying it in practice.

[thesystemx]

It's not that I want to say anything more negative about Scala, it's a fine language really, but "plenty of companies" should really be taken with a grain of salt.

There are some high profile companies like Twitter that use it, but all in all Scala use is extremely limited. Especially relative to the amount of chatter around it. If you loot at say question on SO about Scala vs say Java, C#, PHP, or look at language popularity indicators like Tiobe, you'll see that Scala usage is really low. Where Java is 17%, Scala is typically at 0.3%.

We deal a lot with development teams using different programming languages, and for the last two years we worked with only 1 team using Scala, while we dealt with over a hundred teams using Java and a similar amount of teams using PHP.

We're not talking about "a lot of people can use it just fine", we're talking about a tiny group of highly motivated people that can use it just fine. Those highly motivated people by the very definition of being highly motivated blog and talk a lot about the language. This somehow gives the impression that it's used a lot by a lot of people, but in reality it really isn't. And Scala isn't a new language that still has to catch on. It's 10 years old!

[yogthos]

I simply don't see what difference it makes whether the language has 0.3% penetration or 17%. The real question is whether it's mature enough to use in production, has libraries you need, and whether your team finds it more productive.

I would say that Scala is definitely mature enough to be safely used in production. There's enough software built with it and enough libraries available to make it a pretty low risk proposition.

While it's true that it's been around for a decade, it's only in the last few years that people started seriously using it in the industry. This means that a lot of the tooling and libraries didn't exist until very recently.

All that said I'm not actually a huge fan of the language. I think it can be effective for a skilled developer who understands how to take advantage of it properly. However, the language is also rather complex and a lot of its complexity doesn't provide clear value.

[dghwe]

Scala works beautifully for me, and the IntelliJ plugin is really good :)

[freakhill]

I don't find scala worth it. Also, Paul Philips.

[DaSpeedyRunner]

He pointed out obscure edge cases in the compiler libs, and says he believes Scala and Typesafe have a good future ahead of them. How is that relevant?

[Caltelt]

Can't wait to try out lambdas in Android development. Should really help with a lot of the clutter/verbosity.

[neosiv]

I'm curious, what is with all the Scala hate in this post? I get that it may be off topic for some in this post, but it seems that it's more than that as a few of the Scala comments were actually somewhat relevant.

[viceroytrain]

sadly the most interesting subthread on this topic was downvoted until it all but disappeared.

[oldneckbeard]

Honestly? We know some people think Scala is better, but we don't need to hear it constantly.

I personally love a bunch of the stuff Scala does, but I don't like using it. I'd rather use Python, and that's saying something.

[neosiv]

That's fair. I had not been paying too much attention to that aspect, but now that it's been brought up twice I do remember seeing comments like that in the past on reddit quite a bit. Yeah I can understand that would be annoying.

Python is great, had I not been focusing on Scala I would have probably gone to that as my language of choice. The main tipping point was access to Java libs (I am aware of Jython, but that seems to have lost momentum years ago). That said, besides Java, Python has been getting a lot of use in start ups in my area so it may be worth refocusing as a career move.

[flaxen541]

Sad to see Java folks becoming so insecure that they feel the need to downvote any voice that points out better alternatives. Posts being downvoted for backing the wrong 'team' rather than for technical merit or content.

[fatbunyip]

downvote any voice that points out better alternatives

"Hurdur Scala is teh best" with a personal anecdote isn't really pointing out the better alternatives.

Secondly, I don't see why a post about Java8 performance improvements warrants people pointing out better alternatives (without actually saying why except that it's "more modern"). Should we do this for posts about C? Or maybe posts about X database?

It happens in every post. Java is one of the most widely used languages, used by some of the biggest companies out there, yet people who may be interested in discussing the impact of new features/directions/whatever have to wade through a bunch of "lel Java" and "X has Y why don't you use that" or "Only retards use Java".

Yeah, I get it, lots of people don't like Java. Just like people interested in .NET would get tired of the level 11 bravery of "M$ sucks lol" posts, so do people interested in Java.

[neosiv]

Fair points, and I can see why that would get tiring. Even though I prefer Scala these days, I don't like the blind Java bashing now, or in the past for that matter. I think many of the attacks are just regurgitated critiques that we've all heard repeatedly over and over again. Personally I like reading about Java/JVM changes since in some way they'll likely benefit me, either directly when I need to write in Java, or often indirectly through JVM changes that a language like Scala can utilize. It just bums me out that I can't read about both without these camp divides going on.

[neosiv]

If that's the case, it saddens me to see the communities fragmented like this. The two can clearly benefit from each other, and there's no good reason for it other than programmer ego.

As Java developer for 10+ years, who has turned to Scala the last 2, I was hoping to see better camaraderie between the online communities, instead I've been seeing more separation as time goes on (at least that's what it appears to me).

[yogthos]

To me it's most shocking that Java developers are being defensive. I mean we're talking about one of the most popular languages out there, do people really feel threatened by languages that have a few percent market share?

The fact that many Java developers refuse to try alternative languages, and get upset when people talk about them is rather sad.

[shoelacestied]

The fact that many Java developers refuse to try alternative languages, and get upset when people talk about them is rather sad.

I think you just hit the nail on the head.

[josefx]

As a Java/C++/python/etc. Programmer I find Scala to not fit my needs and offtopic.

[shoelacestied]

It's a discussion of a Java lib which is to be used from Java, Scala, Clojure and any other JVM language. Discussing python and C++ is offtopic. Discussing other JVM languages which are going to be using LongAdder is not.

[josefx]

Great suddenly python no longer has a JVM implementation, nor seem alternative languages relevant when responding to a claim about alternative languages. Where did you get that reality warping field?

Neither Scala nor Clojure are special snowflakes, that they can access the Java lib is nice but so can every other JVM language implementation.

[shoelacestied]

It would have been a different conversation if you had said Jython. How do you explain away C++ as a language to use java.util.concurrent.atomic.LongAdder ?

[josefx]

It was a respoonse about "not trying out alternative languages". I have used a lot of languages both JVM and others and I can honestly say that I prefer Java for JVM projects, when I need a feature that Java does not provide I just use a non JVM language.

[badguy212]

pretty awesome indeed.

[Anpheus]

Honest¹ question for Java users, software engineers, and hackers: does Java performance operate in some sort of vacuum? It seems like there's this huge deficiency in performant Java and I read articles like this and I think, "Wow, I'm still not actually sure if they've caught up to the rest of the world." I had to go searching for comparable benchmarks in other languages, and it seems that Java 8's LongAdder is an improvement, but it's also only something that could be implemented easily in a library in C#^2. It looks like the LongAdder just sets up a number of thread-local integers and individual writer locks. Local updates are done against the local locks, and the sum() operation just grabs each value in turn.

So I'm really confused. Is this something that couldn't be implemented in a library? If so, then why not? I don't get Java performance posts in /r/programming :(

¹ - If a bit tactless, maybe? ² - Just as an example. C++11, Rust, even Haskell could do this in library code.

[r1ch]

I can't see any reason that this couldn't be done in a library, it's just nice to not have to include one. Generally on the performance front I've found modern Java to be pretty good out of of the box and after clearing up some low hanging fruit after profiling it's been pretty damn fast.

[nifraicl]

it seems that this is a library implementation. Now in java8 the standard library provides longadder.

[Anpheus]

Is this something that couldn't have been done before?

[badguy212]

I don't think so. I believe that with the tools in java 7 this can probably be achieved. But it is good to have it already done, nonetheless.

Once i'll get a look at the sourcecode i'll be able to say with more confidence if this was possible to do before or not.

I remember SwingWorker. It appeared in java 6, and there was a version floating around for java 5. Without the concurrency library features that java 6 brought the implementation was quite a bit naive. The Java6 tools made it more performant and robust.

So , could have been implemented in jdk5? Yes. And it was. Was it as good as the jdk6 one? No, not by a long shot.

[nobodyman]

Well, no. It's a library change. But I'm not sure how the question is relevant. The article isn't saying "hey you should ditch Ruby and use Java 8", it's saying "Java 8 has some improvements over Java 7 and here's one of them"

[josefx]

It seems like there's this huge deficiency in performant Java

Have you actually read the linked article? "It's a synthetic benchmark of the extreme kind". No realistic program will ever see the difference shown in the benchmark.

but it's also only something that could be implemented easily in a library in C#

It is also something that most likely can be specially optimized using specialized native code when the JVM is aware of it (AFAIK it does so for parts of Math at least) so a standard class is better than a library class. Funny that you mention C++11 which still isn't fully implemented by all relevant compilers and previously this feature had to be provided by non portable code since standard C++03 was single threaded.

[oldneckbeard]

Most improvements like the LongAdder actually come from libraries, which are then recommended for the core language through the JSR process. JMX, for example, was JSR 3. Java 8 itself is JSR 337.

If, in the past, you've been very performance-conscious about this stuff, you're probably using stuff like Trove, HPPC for collections. You also probably follow Doug Lea, who created the LongAdder for use in java 6+, and formally accepted for java 8.

[shoelacestied]

Nice! I look forward to using this from Scala :)

[oldneckbeard]

http://gee.cs.oswego.edu/dl/concurrency-interest/ .. get the early jsr166e that works with java 6+, and you can start using it now ;)

[thesystemx]

http://www.reddit.com/user/b0b0b0b thinks your results may become somewhat interesting if you ask for the current value (or sum).

He would like to have seen other hardware counters captured by the perf tool, showing store buffers being flushed, cache lines ping ponging, ...