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Java Native Compilation Examined
An Anonymous Coward writes: "DeveloperWorks has an interesting article about compiling Java apps to run as native appplications on the target machine without the need for a JVM."
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What's the point of taking a language that jumps through hoops to be "cross-platform" and cutting it's legs off?
Lets see TowerJ has been out since when ? 1999. Having tried my hand at this I have some reservations. The project I was on ... a large dinosaur of a thing which will remain nameless had 12,000 classes which TowerJ turned into C files which were then compiled by GCC. Resulted in 50 megabyte executables on a Sun. Didn't really solve the problem which wasn't really about speed but throughput. The solution was a better design using servlets and Java Webserver ... result DRAMATICALLY faster without any need for native compilation.
Mind you I noticed in the IBM article that the memory footprint was much smaller. That might be nice.
Bitter and proud of it.
Most notably, there is very little support for AWT, making GCJ unsuitable for GUI applications.
That's the real shame of the matter. Java shines most in its ease-of-use for creating complex GUIs -- unfortunately that's also where the worst memory/performance problems appear. For instance, Swing is good for client apps if you can ship with minimum RAM requirements of 64+ mb (and even that's cutting it close). Performance is most important in the UI, where the user notices any lack of responsiveness. Hopefully some Java native compilers will help out here.
Different compilers support differing levels of class library; Excelsior JET is one compiler that claims to completely support AWT and Swing.
Maybe there's hope yet!
The big advantage of GCJ isn't speed, it's the vastly better interface to C++ code (CNI vs. JNI). Of course, using that really does make your code non-portable.
I always thought Java was very interesting with it's cross-platform compatibility and whatnot. But as everyone has noted, it's painfully slow. I always wondered why people hadn't implemented a native-code compiler for it. Sure, with bounds-checking and garbage collection, natively compiled Java will still be slower than natively compiled C++.
The point is, Java is really just another programming language. What's wrong with allowing developers the opportunity to write their natively compiled software in a solid, object-oriented language that doesn't have all the backwards-compatability issues that C/C++ has?
Whether this will be useful, I dunno. But it opens up options, and that's always a good thing.
Learn to Play Go
Operator overloads make it *way* too easy to write code that is difficult to follow. The ability to add, subtract, etc. objects *rarely* makes perfect sense when you consider everything that the object represents. Really, the lack of operator overloads is not a big deal, perhaps even an advantage, if you ask me. (IMHO)
-bugg
I'm not going to try to champion Java, JITs, or native compilation, I'm just going to point out what's wrong with this "study".
This has to be the third or fourth weak study of Java performance I've seen over several years. Issues such as whether or not all Java features are in place in the native compilations (e.g. array bound checking, but note that GCJ turns this on by default) or what sort of optimizations are performed by the native compiler and JVMs are completely ignored. The author also suggests that compiling from bytecode to native code is the natural route when it's quite possible that gains could be made by compiling directly from source to native. While GCJ accepts either Java source or bytecode, it's not clear from the documentation I've read whether or not it first translates source to bytecode or goes straight from source to native.
When comparing disk space, the author comments that an installed JVM can be up to 50 MB vs. 3 MB or so for libgcj. This is a ridiculous comparison since those directories probably include all of the tools, examples and libraries, and as far as I know, libgcj doesn't include the whole J2SE API set, so it's nowhere near a fair comparison. It's a pretty limited set of benchmarks for making these judgements too.
I played around with native compilation of Java a few years ago. At one point (probably around 1996/7?) native compilers could offer noticable gains over Sun's JVM on a numerically intensive application (neural network stuff). However, after the initial versions of HotSpot and IBM's JIT, I couldn't find a native compiler that gave competitive performance on similar apps. I think this is largely due to underdeveloped native compilers with poor optimization (HotSpot is quite insane in its runtime optimizations).
Anyway, I sure hope IBM doesn't pay too generously for studies this poor. Its final message is essentially "who knows?" - not terribly useful.
Alea
I found it interesting that this author, an IBM researcher, chose to only test a single java-to-native compiler, the GCJ (GNU product). This is an immature open-source package that I would not expect much performance from. His paper rehashes a lot of really basic info, then gives some performance results which show IBM's JVM spanking Sun, Kaffe, and GCJ. This is no great surprise; IBM is tooting it's own horn - fine, they deserve to IMHO. But as an exercise in "the state of native compilation" it's useless. What would actually be really useful is a comparison that also included at least a half-dozen other major players in the java native compiler market. I suspect you'd see some different results.
As an aside; I see people call Java "painfully slow," but in my experience it's not that painful post 1.3. I'm not giving you benchmarks, and anti-Java people will just "no" me, but these are my experiences after a few hundred thousand lines of Java code over the past few years. Anyway, it's a good exercise to ask naysayers what _their_ basis is; they often have none.
Also, as other posters have pointed out, the speed loss must be seen in the runtime safety context, as bounds checking and garbage collection yield stability and security dividends and, at the end of the day, we almost always want those things and are willing to wait the extra few ms for the guarantees.
All these complaints about speed are especially ironic given how many massive wasters there are in the modern computer, _especially_ in Windows NT/2k/XP.
But the biggest flaw in this Java vs. C debate is that often you don't get a choice between writing code in Java vs. C/C++, since you don't have the extra 50% in your time budget to do C/C++, and your real choice is between Java and VBScript...
All the people shouting "I can write C++ 10 times as fast as you can write Java, loser" please form a line in an orderly fashion, you will be spanked in the order you arrive...
We're on the road to Tycho.
I would argue that .equals and .plus make code more difficult to follow. The anti-overloading arguement always goes: "Someone will overload operator== to delete files."
.equals().
But that same person can just call their Java file deletion function
So the so called 'advantage' is just more marketing bullshit.
And how about the case of a Matrix class? Which is more readable:
Matrix b = a.plus(b.multiply(c));
vs.
Matrix b = a + b * c;
Using template trickery (see Blitz++ for examples) you can even optimize away all the implicit temporaries in the C++ example. With Java, you're stuck both with the less readable code, _AND_ unneeded temporary objects.
Lots of experts here.
Some experts who have never used Java want to tell me that it's no good, and will never be any good--why? They don't know, but they know!
And some experts who want to tell me all about why Java's compilation, why it is hard or easy even though they really don't know anything about a compiler.
And some experts on Java's market share who really don't know anything about who uses Java.
And some experts who sat in a room where Java was... gosh gee... being implemented, telling me... well I don't quite know what, but gosh!
So many experts here--I must be reading slashdot!
But that same person can just call their Java file deletion function .equals().
.close()
Of course they can..and that person would be a goddamn fool.
The point is that an operator overload might make complete sense to the person that programmed it. The next person who looked at it may have used a different convention and interprets it differently.
As an example, I overload (file--) to delete the file. But the convention you read in the latest issue of 'L33T Developer' indicates that (file--) should mean close the file handle. You look at the code, make somes changes and your clients file was just deleted.
And BTW, I would never have called a function that deleted a file
Jason.
-
for
(long test=2; test < i; test++)
If the compiler generates slow code for that, something is very wrong in the compiler.{ if (i%test == 0) { return false; }
}
On the safety front, subscript checking is almost free if done right. Subscript checking can usually be hoisted out of loops. Old studies on Pascal optimization showed that 95% of subscript checks can be optimized out at compile time without loss of safety. GCC, though, being a C compiler at heart, isn't likely to know how to do that. Merely putting a Java front end on it doesn't make it a Java compiler deep inside.
Java, in the form of EJBs and servlets, is becoming fairly common on "big iron". One reason is indeed the cross-platformability of it. But, frankly, most often a change in platform accompanies a change in framework. For example, a switch from UNIX servers to a mainframe may accompany a switch from CGIs to an application server (such as Websphere). The dramatic switch here is probably not from UNIX to OS/390 (after all, OS/390 has a POSIX layer), but from CGIs to Websphere. So, as you said, it's not really cross-platformability which is driving Java in the server realm. I think the principal reason is that Java provides (at least some semblance of :) a language-level security model. By security, I don't mean crypto and virii and external attacks. I mean an application is secure from itself, and its (all too human) programmers.
A common complaint of people writing in a language that lacks feature x is to declare feature x useless or dangerous. Operator overloading makes sense in certain situations, especially where math semantics are being modeled.
Are operator overloads misused? Sure. So are knives, but that doesn't mean that cooks shouldn't use knives.
But you wanna talk about language features that Java lacks? How about enums? Why leave those out? And whats with this whole "bean" concept? Why can't that be a first class concept with real syntactical support instead of this asinine get___ set___ crap?
I could be biased, though.
meh.
It took forever to compile, but once it was done, I had a (large) executable for my native platform, windows.
It ran about 30% slower than the JDK. There are a number of things that are still pretty slow in java, but in general, it's a pretty fast language these days. JIT compilers and hotspot to a good job. It can never be as fast as C++ due to things such as GC, but the performance tends to be close for most applications.
This is indeed interesting, but I think it is entirely irrelevant. Speed of execution is usually about 7th on the list of important-stuff-im-thinking-about when choosing a language and starting a project. There are so many more important things, such as maintainability, scalability, code reusability, code robustness (the number of stuff you get so easy compared to C++ just leaves you wondering how you could ever program in C++ again), you know the stuff. These things are often far more of an issue than raw performance. Look at Slashdot, it's written in perl, presumably because they thought it was easier to write the website in, not because it was the fastest thing around.
dominionrd.blogspot.com - Restaurants on
I agree with you relative to C/C++, and I was using Java heavily a couple of years ago. But now I've moved on to higher-level languages such as Perl, Python and Ruby. They each have APIs that provide functionality similar to Java, but usually simpler and more intuitive. They also don't have licensing policies or agendas driven by one particular corporation..
I usually get the same job done with 1/2 or 1/3 the lines of code as with Java. I've also found that once you free your mind from the strong-typing yoke, you can transform your concepts into reality much more efficiently.
It's funny that a few years ago I had to argue to the PHBs that Java was a valid solution. Now, they are set on Java, and I have to argue that a better solution has emerged as support for other languages has matured.
I've used both C++ and Java extensively (although I haven't used garbage collected C++).
For ease of coding, I find that Java simply outshines C++ because it doesn't leave me dealing with low level stuff, like pointers.
An occasional big time-killer with C++ is trying to debug something that corrupts memory.This doesn't happen with Java (although you can muck up the synchronization with threading and get unpredictable results which is just about as bad).
On the other hand, if I want performance (such as writing image processing software), I'll go with C++ (or assembler), as there is no way that Java can compete on speed for low level stuff.
And even the awful C++ templates are better than no templates at all.
The only certainty is entropy.
Sun pushed *binary* compatibility so hard because Java's claim to fame was taking what loaded into your browser from static content to full executable apps -- making the underlying OS irrelevant in the process. "Death to Windows!"
It didn't work out. Client side Java is essentially dead. "Death to Java applets!" C#/.Net will become what Java only dreamed it could be -- but, sadly, only on Windows.
In the meantime, Java hit pay dirt on the server, because the language is so easy and productive to work in and the result is so portable.
Source portability would have been sufficient on the server, though. I can't prove it, but I strongly suspect they could have created a better server-side programming language if they had designed for 100% *source* portability, then instead of constraining themselves to binary portability and security sufficient for running *anybody's* binaries on *anybody's* client, had instead optimized for high performance plus ease of rapid, bug-free development -- more like Eiffel.
"Those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded."