Java Performance Tuning, 2nd Ed.

cpfeifer writes "Performance has been the albatross around Java's neck for a long time. It's a popular subject when developers get together "Don't use Vector, use ArrayList, it's more efficient." "Don't concatenate Strings, use a StringBuffer, it's more efficient." It's a chance for the experienced developers to sit around the design campfire and tell ghost stories of previous projects where they implemented their own basic data structures {String, Linked List...} that was anywhere from 10-50% faster than the JDK implementation (and in the grand oral tradition of tall tales, it gets a little more efficient every time they tell it)." Want to kill the albatross? Read on for the rest of cpfeifer's review of O'Reilly's Java Performance Tuning, now in its 2nd edition.

Java Performance Tuning, 2nd Edition
author	Jack Shirazi
pages	570
publisher	O'Reilly and Associates
rating	9/10
reviewer	cpfeifer
ISBN	096003773
summary	It's the most up to date publication dealing specifically with performance of Java applications, and is a one of a kind resource.

Every developer has written a microbenchmark (a bit of code that does something 100-1000 times in a tight loop and measure the time it takes for the supposed "expensive operation") to try and prove an argument about which way is "more efficient" based on the execution time. The problem, is when running in a dynamic, managed environment like the 1.4.x JVM, there are more factors that you don't control than ones that you do, and it can be difficult to say whether one piece of code will be "more efficient" than another without testing with actual usage patterns. The second edition of Review of Java Performance Tuning provides substantial benchmarks (not just simple microbenchmarks) with thorough coverage of the JDK including loops, exceptions, strings, threading, and even underlying JVM improvements in the 1.4 VM. This book is one of a kind in its scope and completeness.

The Gory Details

The best part of this book is that it not only tells you how fast various standard Java operations are (sorting strings, dealing with exceptions, etc.), but he has kept all of the timing information from the previous edition of the book. This shows you how the VMs performance has changed from version 1.1.8 up to 1.4.0, and it's very clear that things are getting better. The author also breaks out the timing information for 3 different flavors of the 1.4.0 JVM: mixed interpreted/compiled mode (standard), server (with Hotspot), and interpreted mode only (no run time optimization applied).

Part 1 : Lies, Damn Lies and Statistics
The book starts off with three chapters of sage advice about the tools and process of profiling/tuning. Before you spend any time profiling, you have to have a process and a goal. Without setting goals, the tuning process will never end and it will likely never be successful.

The author outlines a general strategy that will give you a great starting point for your tuning task forces. Chapter 2 presents the profiling facilities that are available in the Java VM and how to interpret the results, while chapter 3 covers VM optimizations (different garbage collectors, memory allocation options) and compiler optimizations.

Part 2 : The Basics
Chapters 4-9 cover the nuts and bolts, code-level optimizations that you can implement. Chapter 4 discusses various object allocation tweaks including: lazy initialization, canonicalizing objects, and how to use the different types of references (Phantom, Soft, and Weak) to implement priority object pooling. Chapter 5 tells you more about handling Strings in Java that you ever wanted to know. Converting numbers (floats, decimals, etc) to Strings efficiently, string matching -- it's all here in gory detail with timings and sample code.

This chapter also shows the author's depth and maturity; when presenting his algorithm to convert integers to Strings, he notes that while his implementation previously beat the pants off of Sun's implementation, in 1.3.1/1.4.0 Sun implemented a change that now beats his code. He analyzes the new implementation, discusses why it's faster without losing face. That is just one of many gems in this updated edition of the book. Chapter 6 covers the cost of throwing and catching exceptions, passing parameters to methods and accessing variables of different scopes (instance vs. local) and different types (scalar vs. array). Chapter 7 covers loop optimization with a java bent. The author offers proof that an exception terminated loop, while bad programming style, can offer better performance than more accepted practices.

Chapter 8 covers IO, focusing in on using the proper flavor of java.io class (stream vs. reader, buffered vs. unbuffered) to achieve the best performance for a given situation. The author also covers performance issues with object serialization (used under the hood in most Java distributed computing mechanisms) in detail and wraps up the chapter with a 12 page discussion of how best to use the "new IO" package (java.nio) that was introduced with Java 1.4. Sadly, the author doesn't offer a detailed timing comparison of the 1.4 NIO API to the existing IO API. Chapter 9 covers Java's native sorting implementations and how to extend their framework for your specific application.

PART 3 : Threads, Distributed Computing and Other Topics
Chapters 10-14 covers a grab bag of topics, including threading, proper Collections use, distributed computing paradigms, and an optimization primer that covers full life cycle approaches to optimization. Chapter 10 does a great job of presenting threading, common threading pitfalls (deadlocks, race conditions), and how to solve them for optimal performance (e.g. proper scope of locks, etc).

Chapter 11 provides a wonderful discussion about one of the most powerful parts of the JDK, the Collections API. It includes detailed timings of using ArrayList vs. LinkedList when traversing and building collections. To close the chapter, the author discusses different object caching implementations and their individual performance results.

Chapter 12 gives some general optimization principles (with code samples) for speeding up distributed computing including techniques to minimize the amount of data transferred along with some more practical advice for designing web services and using JDBC.

Chapter 13 deals specifically with designing/architecting applications for performance. It discusses how performance should be addressed in each phase of the development cycle (analysis, design, development, deployment), and offers tips a checklist for your performance initiatives. The puzzling thing about this chapter is why it is presented at the end of the book instead of towards the front, with all of the other process-related material. It makes much more sense to put this material together up front.

Chapter 14 covers various hardware and network aspects that can impact application performance including: network topology, DNS lookups, and machine specs (CPU speed, RAM, disk).

PART 4 : J2EE Performance
Chapters 15-18 deal with performance specifically with the J2EE APIs: EJBs, JDBC, Servlets and JSPs. These chapters are essentially tips or suggested patterns (use coarse-grained EJBs, apply the Value Object pattern, etc) instead of very low-level performance tips and metrics provided in earlier chapters. You could say that the author is getting lazy, but the truth is that due to huge number of combinations of appserver/database vendor combinations, it would be very difficult to establish a meaningful performance baseline without a large testbed.

Chapter 15 is a reiteration of Chapter 1, Tuning Strategy, re-tooled with a J2EE focus. The author reiterates that a good testing strategy determines what to measure, how to measure it, and what the expectations are. From here, the author presents possible solutions including load balancing. This chapter also contains about 1.5 pages about tuning JMS, which seems to have been added to be J2EE 1.3 acronym compliant.

Chapter 16 provides excellent information about JDBC performance strategies. The author presents a proxy implementation to capture accurate profiling data and minimize changes to your code once the profiling effort is over. The author also covers data caching, batch processing and how the different transaction levels can affect JDBC performance.

Chapter 17 covers JSPs and servlets, with very little earth shattering information. The author presents tips such as consider GZipping the content before returning it to the client, and minimize custom tags. This chapter is easily the weakest section of the book: Admittedly, it's difficult to optimize JSPs since much of the actual running code is produced by the interpreter/compiler, but this chapter either needs to be beefed up or dropped from future editions.

Finally, chapter 18 provides a design/architecture-time approach towards EJB performance. The author presents standard EJB patterns that lend themselves towards squeezing greater performance out of the often maligned EJB. The patterns include: data access object, page iterator, service locator, message facade, and others. Again, there's nothing earth shattering in this chapter. Chapter 19 is list of resources with links to articles, books and profiling/optimizing projects and products.

What's Bad?

Since the book has been published, the 1.4.1 VM has been released with the much anticipated concurrent garbage collector. The author mentions that he received an early version of 1.4.1 from Sun to test with. However, the text doesn't state that he used the concurrent garbage collector, so the performance of this new feature isn't indicated by this text.

The J2EE performance chapters aren't as strong as the J2SE chapters. After seeing the statistics and extensive code samples of the J2SE sections, I expected a similar treatment for J2EE. Many of the J2SE performance practices still apply for J2EE (serialization most notably, since that his how EJB, JMS, and RMI ship method parameters/results across the wire), but it would be useful to fortify these chapters with actual performance metrics.

So What's In It For Me?

This book is indispensable for the architect drafting the performance requirements/testing process, and contains sage advice for the programmer as well. It's the most up to date publication dealing specifically with performance of Java applications, and is a one-of-a-kind resource.

---

You can purchase Java Performance Tuning, 2nd Edition from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

Isn't this the compiler's job?

[chrisseaton]

If all these performance hacks are documented, why doesn't the compiler implement them?

I've often found that will bytecode languages (Java, C#...) the bytecode instructions are made for the language so that the compiler can just throw them out easy peasy, but they seem to overlook the sort of optimizations that C compilers, for example, work hard to implement.

Re:Isn't this the compiler's job?

[p3d0]

Do you mean the Java compiler or the JIT compiler? If you mean the JIT compiler, keep in mind that JIT compilation occurs at runtime, so this kind of analysis would be prohibitively expensive.

In either case, I think they analysis you're asking for is the kind that's easy for a human to do, but harder for an algorithm to do automatically. I don't know what's involved, and it could probably be done, but to prove that these transformations are safe is no mean feat.

Re:Isn't this the compiler's job?

[cmburns69]

With non-bytecode langauges, the compiler can optimize to the environment. It can re-order code based on the fastest execution time for the platform the code is compiled for.

Java (and other bytecode languages) were desinged to run well not just on a single platform, but on a variety of platforms. So as a trade-off, you lose environment-specific optimizations at compile time.

JIT JRE/compilers can work to prevent this. They can further optimize the bytecodes at execution time because they are platform specific.

An online Starcraft RPG? Only at [netnexus.com]
In soviet Russia, all your us are belong to base!

Re:Isn't this the compiler's job?

[briaydemir]

If all these performance hacks are documented, why doesn't the compiler implement them?

The most common reason is that most performance hacks and optimizations are not decidable, and you want a compiler to implement only decidable algorithms becuase those are the ones that enable a compiler to be deterministic. It is usually much easier for a person, i.e., human, to determine what can be done, than it is for a machine to determine that exact same thing.

Consider the following piece of code.

boolean f(int[] a, int[] b)
{
int x = a[0];
b[0] = a[0] + 2;
int y = a[0];
return (x == y);
}

Does f always return true? Only if we can prove that a and b never point to the same array. A person maybe able to do this, but a machine would have great difficulty (assuming the machine could even do it).

So to sumarize, compiler's don't implement many optimization hacks becuase then they might not be deterministic, and that is a bad thing.

Re:Isn't this the compiler's job?

[steve_l]

If you can assert statements (a!=b) at the start of the code, and the compiler uses these assertions then it can act on them. but nobody does, no compiler supports it, etc, etc. Visual C++ does support this trick, but I have never encountered its use in a real project.

I'd be happy with cache prefetch hints in both Java and C#, and portable hinting in C++ (you can do it with ugly macros)

Re:Isn't this the compiler's job?

[Anonym0us Cow Herd]

If someone were building a compiler that contemplated making such optimizations, wouldn't it be better to have an option to output optimization hints to the programmer? If I use a certian switch, the compiler emits another output file of notes about the source code, and what optimizations it suggests might be in order.

Naturally, the programmer might see that since both array parameters a and b point to the same array, that this is not really a possible optimization. This realization by the programmer i

Re:Isn't this the compiler's job?

[chrisseaton]

Think about the string object problem - people have to use stringbuffer because strings are immutable.

When a program thrashes strings around, why doesn't the compiler detect that, and switch to a string buffer object to perform those operations, and then convert the final result back to a string?

Re:Isn't this the compiler's job?

[jd10131]

Having a compiler swap objects out from under you would be

1. Tricky to implement properly
2. Rude

However, emitting a warning when the compiler thinks you could do a better job with a StringBuffer might be nice.

Re:Isn't this the compiler's job?

[chrisseaton]

"Having a compiler swap objects out from under you would be ... rude"

I don't mean it to swap the object out, just use a temporary object for the operation.

When you say

string foo = "Hello, ";
foo += "World!";

You just want foo to hold the two strings concatenated, you don't care how the compiler did it. The compiler could create a temp stringbuffer object there for that operation, converting back to string and assigning to foo.

I don't see how that's rude, because the programmer wouldn't even know that it'

Re:Isn't this the compiler's job?

[ruriruri]

Actually, most java compilers do exactly what you suggest. However, consider:

String foo = "Ripple in still water\n";
foo += "When there is no pebble tossed\n";
foo += "Or wind to blow.";

In this case, the compiler does the following steps:

1. Create new string "foo" with the initial value (this may already exist).
2. Turn foo into a StringBuffer and append "When ..."
3. Turn foo back into a String.
4. Turn foo into a StringBuffer and append "Or..."
5. Turn foo back into a String.

So you can see this is not

Re:Isn't this the compiler's job?

[dubious9]

actually, IIRC, that's what the compiler already does for inline concatenation i.e. System.out.println(thisstring+thatString);

String/StringBuffer

[toriver]

It does under the hood whenever you use + for concatenation; this is why using String + String in a loop is ineffective: You create a new StringBuffer object per iteration. The solution in this case is to declare the StringBuffer outside the loop and use append() explicitly within.

For concatenating two strings, the concat() method can be faster than using StringBuffer, since it only needs to create a new char[] and do a (fast) arraycopy from the two internal arrays.

Also, everyone should be aware of the 1.4.1 memory leak associated with using StringBuffer's toString() and setLength() methods.

Re:String/StringBuffer

[bay43270]

It does under the hood whenever you use + for concatenation; this is why using String + String in a loop is ineffective: You create a new StringBuffer object per iteration. The solution in this case is to declare the StringBuffer outside the loop and use append() explicitly within.

I think your missing the point the parent was trying to make. Aren't there much bigger things to worry about than writing around bugs in the compiler?

Two years ago, everyone used StringBuffer.. today, everyone knows the us

Re:Isn't this the compiler's job?

[gmarceau]

For most of theses transformations to be correct, the compiler has to prove there is only one pointer to the object -- in the whole program. Whole-program analyses are expensive, and so are point-to [nec.com]analysis. And there is just not that kind of time to spare in a JIT, where every second spent analysing the program is time spent not executing it.

The optimization the book proposes are all hit-or-miss adventures. Even for a programmer with intimate knowledge of the code, it is sometime difficult to predict if a change will help or imper performance. The compiler has even less chance to do so correctly -- and nobody like a compiler which slows down their code trying to optimize it.

Definite purchase

[Timesprout]

I have drastically cut back on my tech book purchases in recent times but this book will definitely be on my shopping list. The First edition offered many insights into not only getting the best performance from Java but also solid guidelines for when and where to apply optimisations.
As a side note I would disagree about performance being an albatross for Java. Well written Java code can be very high performant just as poorly written code in ANY language can perform slowly. Many of the performance issues associated with Java are inexperienced developers using inappropriate methods and objects.

New Title

[borg05]

Java Performance Tuning: A course in C programing

Re:New Title

[Anonymous Coward]

Writing secure server applications that take less than several minutes to respond: A course in C++ programming

Writing complex enterprise systems that don't get cancelled, because they don't perform and are written by former Taxi drivers turned Java programmers: A course in C++ programming

Is this a review or a synopsis?

[rfischer]

there is a difference, you know.

Correct ISBN is 0596003773

[zipwow]

The bn.com link is broken for me, here's the correct ISBN:

0596003773

Re:Correct ISBN is 0596003773

[gid]

for the lazy [bfast.com]

Re:Correct ISBN is 0596003773

[MojoRilla]

Or buy it from Amazon here [amazon.com] and save $4.49.

Java Strings are the main problem

[Anonymous Coward]

Each String is around 64 bytes of memory minimum. What a stupid decision to make such a fundamental data type so heavy weight.

Re:Java Strings are the main problem

[sohp]

... because no one will ever need more than 64 bytes.

Re:New math?

[julesh]

There's an additional 16 bytes involved in the object class descriptor pointer and the reference to the object's monitor (*2 - one for the String and one for the char[], which is a fully fledged object in its own right), plus probably a couple of bytes overhead for the memory allocator. About 32 bytes seems reasonable. I think the point to make is, though, there is no _sensible_ way of making the string any smaller without sacrificing performance. Plus the objects have the ability to share the array betw

Re:New math?

[Anonym0us Cow Herd]

You only need 4 bytes to make reflection work. Each object has a pointer to what class it is. The class information has everything else, the vtable so to speak, what interfaces are implemented, etc. All String objects have one single pointer to a common String class object the defines what a String is, what its members are, what its methods are, etc. everything needed for reflection. Think of the vtable as being more than just an array of method pointers, but meta information (the class object) about th

Java performance better in the Sun IDE?

[192939495969798999]

I have noticed my JAVA programs run considerably faster under the Sun Forte/One IDE. Once the JAVA app is on its own (especially through a browser), it slows considerably. Does anyone else have experience with this phenomenon?

Re:Java performance better in the Sun IDE?

[dubious9]

I know with Eclipse, that it keeps an instance of the VM running so that it doesn't have to start every time you want to run or debug the program. This would only affect start up times though.

Re:Java performance better in the Sun IDE?

[los furtive]

Your IDE has its own Java VM running, and it could be different from the one you have installed. Most, if not all IDEs will let you choose which VM to use (for example I use 1.3.1_07 for work projects while using 1.4.1_02 for my own stuff, both from the same IDE).

Process

[spakka]

The book starts off with three chapters of sage advice about the tools and process of profiling/tuning. Before you spend any time profiling, you have to have a process and a goal. Without setting goals, the tuning process will never end and it will likely never be successful.

No, you have to profile first. Profiling will tell you whether there is even any point in tuning, and, if so, what goals are reasonable.

Re:Process

[egoots]

No, you have to profile first. Profiling will tell you whether there is even any point in tuning, and, if so, what goals are reasonable.

It's a classic chicken and egg conundrum... If your program meets your performance requirements, why spend time profiling in the first place (but perhaps this is always necessary with Java apps).

I still believe that premature optimization is way too prevalent, unnecessary, and problematic. I recommend the following approach:

Make the program function correctly first

If it

What performance issues?

[Anonymous Coward]

Java has performance troubles? I thought we were all supposed to deny that. Did I miss a memo or something?

Java doesn't cut it

[AirLace]

We ported some of our internal Java business applications to C# for use with Mono, and emperical results already suggest the solution is several times faster than the Java code. The port was very easy, with each line of Java code mapping onto one line of C# or less. Porting the UI to Gtk# was more difficult, but we find the Gtk# code more maintainable and the UI, along with the Gtk+ WIMP [sourceforge.net] plugin integrates much more nicely with Windows than SWING. We'll be investigating a switch to Linux over the next few months for some of our Point-of-Sales terminals as a result, and it should be easy thanks to the portability of Mono and Gtk#.

We also ported some of our backend tools for use with Mono. In use with the newly released Mono JIT runtime, Mini [ximian.com], we've achieved some truly stunning results. It turns out that some of the optimisations in the new JIT are better than those used by GCC, so once the code is loaded in memory, it performs better than raw C code. Although I don't yet have hard numbers to back up these result (the transition is still in progress), it has to be said that Mono is the real answer to Java performance. Being Open Source, we can also contribute back to the runtime to make it better suit our needs. It also plays nicely with RedHat 9's NPTL threading implementation, which is more than I can say for the current crop of Java JREs.

Re:Java doesn't cut it

[sbrown123]

We ported some of our internal Java business applications to C# for use with Mono, and emperical results already suggest the solution is several times faster than the Java code.

You could have saved yourself some porting by just compiling your java code with GCJ. GCJ allows you to compile your java byte code to native executables.


Porting the UI to Gtk# was more difficult, but we find the Gtk# code more maintainable and the UI, along with the Gtk+ WIMP [sourceforge.net] plugin integrates much more nice

Re:Java doesn't cut it

[AirLace]

You could have saved yourself some porting by just compiling your java code with GCJ. GCJ allows you to compile your java byte code to native executables.

This might become an option in a few years, but the GNU classpath is as yet not complete enough for our years. We actually didn't find gcj output that performant, despite it being compiled to native code. The JRE still beat it in many cases.

Use SWT with Java. SWT uses Windows native widgets on Windows or GTK on Linux.

We also investigated this. SWT is a _horrendous_ API which offers very little abstraction. You end up writing your code once for the Gtk+ target, and again for the native Windows target. It isn't really a cross-platform abstraction like WxWindows, and it's probably the reason why the Eclipse codebase is so large. You end up writing your application for each UI target platform. Gtk# runs and integrates with the platform instead, so you only write your code once.

Either your telling a big lie or dont have your facts straight. Unless you can show hard facts your not going to sway anyone into believing interpreted code outperformed compiled.

I did mention the results are empirical, but they're also pretty obvious from where I stand. You don't need benchmarks when something performs, in some cases, eight times faster than the original implementation. I may well put togther some benchmarks and post them to mono-list or linuxtoday.com. I don't have benchmarks yet; does that make me a liar? Sigh.

What is exactly wrong with Java's use of native threads on Linux boxes?

It's pointless to interface with the threads layer directly when pthreads exists. It makes the runtime essentially unportable to other unices/operating systems. Mono plays nicely with the environment, so the runtime can just be compiled on any POSIX-compilant system. Linux is great, but being attached to it so firmly that your application breaks when Linus changes some internal interfaces is not.

Re:Java doesn't cut it

[AirLace]

Sorry, that should be "for our uses".

Re:Java doesn't cut it

[21mhz]

We also investigated this. SWT is a _horrendous_ API which offers very little abstraction. You end up writing your code once for the Gtk+ target, and again for the native Windows target. It isn't really a cross-platform abstraction like WxWindows, and it's probably the reason why the Eclipse codebase is so large.

I've seen the Eclipse codebase, and I'd like to hold you to an explanation. The only modules that are duplicated per platform are the SWT implementations and some minor stuff also tied to the plat

Re:Java doesn't cut it

[mritunjai]

I've been using eclipse and SWT for quite sometime.

We also investigated this. SWT is a _horrendous_ API which offers very little abstraction. You end up writing your code once for the Gtk+ target, and again for the native Windows target.

Complete BS !!

SWT offers a very high level of abstraction. If you want a still higher level of abstraction, then use the jface interface.

I've written a filesystem tool for QFS (QNX file system) and it runs without a single line of modification on QNX, windows and s

Re:Java doesn't cut it

[Glock27]

OK, all you "geniuses" that moderated the parent's parent up to +4 (incorrectly)...mod the parent of this post to +5 informative. :-)

While you're at it, the parent's parent (grandparent?) could use about 4 "overrated" mods.

TIA!

Re:Java doesn't cut it

[Glock27]

We actually didn't find gcj output that performant, despite it being compiled to native code.

Really? One numeric (i.e. HPC) benchmark using gcj which was investigated in detail here on Slashdot (almabench) [coyotegulch.com] was within a few percent of the best gcc time...not bad by most folk's standards. ;-)

We also investigated this. SWT is a _horrendous_ API which offers very little abstraction. You end up writing your code once for the Gtk+ target, and again for the native Windows target. It isn't really a cross-platf

Re:Java doesn't cut it

[Glock27]

I see in the time it took me to post my last reply, the parent was modded up yet again, all the way to +5. What a travesty.

I hope people don't think Slashdot moderation ensures accuracy, it certainly doesn't. :-P

Another explanation for performance increases

[zipwow]

Since other posters have already indicated that gcj /does/ lead to better performance, I think I have a cause for your performance increase beyond "Java sux":

Re-implementation removed the bottleneck.

What kind of profiling did you do against your original Java application? Where was the time being spent? I've worked on some pretty high-performance java applications, and have found them to be quite scalable.

If you're talking about GUI responsiveness (not client/server or high processing interactions), th

Re:Another explanation for performance increases

[Glock27]

Interestingly, the original AWT used components based on native ones for just this reason, but that turned out to be problematic.

AWT was a fairly poorly designed library. As I recall, it was designed at Sun in something like two weeks.

At any rate, SWT seems a much better job, also using native widgets.

just-in-time compilation

[Submarine]

"interpreted code outperformed compiled"

All modern JREs have a JIT compiler, which compiles frequently used functions to native code. It is possible that the JIT compiler in the JRE is better than gcj.

From a more general point of view, it is possible for JIT compilation to optimize better than ordinary compilation. This is because the JIT compiler has access to dynamic profiling information that is not available to the "normal" compiler (though you can feed profile information from benchmarks to some "nor

Re:Java doesn't cut it

[Headius]

You certainly are banking on Microsoft remaining benevolent toward Mono. I'm not sure why it's so hard for people to see that MS has absolutely nothing to gain from Mono becoming popular and widely used, except that it will draw people into the real .NET platform, which only runs under Windows.

Mono on Linux will always lag behind the Windows-based implementations from Microsoft, and Microsoft knows it. They've opened up the runtime, but not the class libraries that make the platform useful. The result is t

Inherent performance issues

[MSBob]

There are certain design decisions that were made by the java team that limit java's performance in a number of ways. Lack of stack objects comes to mind and collections that cannot store basic types.

That said for most network centric applications java is plenty fast. Now if we only stopped short of introducing the unbelievable overhead of XML's excessive verbosity...

Re:Inherent performance issues

[LarryRiedel]

Other things I think are major problems are inability to manage memory, lack of fundamental thread synchronization primitives and predictability, massive native (C) code impedance mismatches, and the enormous program (JVM) startup overhead.

JDK 1.5 should help with the JVM startup and threading problems. I hope someday for the ability to manage memory efficiently, at least letting me repeatedly resurrect garbage objects and get some sort of guarantees about when collection will happen.

Larry

idiots.;

[mandrake*rpgdx]

Why does programming languages have to be an either or situation? Everyone here assumes that anyone who programs in JAva does not know C/C++...why is that? Can't someone know multiple prog langs? I know many (too many too really list here) and find it asinine that people really think that everyone should just program in one lang.

Re:idiots.;

[iapetus]

Because the sort of people who like to get involved in discussions about whether C# is 'better' than Java or Java is 'better' than Perl or crunchy peanut butter is 'better' than textured masonry paint can't cope with more than one thing at a time, and tend to apply their religious zealotry with great vigour.

Those of us who can program in more than one language and know that sometimes it's a matter of choosing the right tool for the job (peanut butter for sandwiches, masonry paint for walls) tend to go through three stages:

1) Try to engage in such discussions on the premise that there's actual intelligent debate going on.

2) Discover ourselves becoming violently opposed to whatever rant we're reading at the time, writing tracts about how Java sucks when we're reading the work of a Java fanatic and drooling about the glory of Java when faced with a C++-toting moron.

3) Either give up in disgust and let the language fanboys get on with it, or sit on the sidelines and snipe at both sides - similar to stage 2, but more consciously applied. Normally that progresses towards giving up, though, since the zealots are just too easy and predictable...

More efficient != better

[brianjcain]

"Don't concatenate Strings, use a StringBuffer, it's more efficient."

Perhaps it is more efficient. I say, let the compiler do it for me. Code like this:

final String foo = frob + " noz " + baz.barCount()
+ " bars found";

is much more readable/maintainable than

StringBuffer fooBuff = new StringBuffer();
fooBuff.append(frob);
fooBuff.ap pend(" noz, ");
fooBuff.append(baz.barCount());
fooBuff.appe nd(" bars found");
final String foo = fooBuff.toString();

Re:More efficient != better

[Anonymous Coward]

That's not the kind of situation that's being talked about. In fact, that case is already done by the compiler.

final String foo = frob + " noz " + baz.barCount()
+ " bars found";

becomes

final String foo = new StringBuffer (frob).append (" noz ").append (baz.barCount()).append (" bars found").toString ();

The problem is when people do things like:

String s = "";
while (hasMoreData ()) s = s + nextCharacter ();

which becomes

String s = "";
while (hasMoreData ()) s = new StringBuffer (s

Re:More efficient != better

[blamanj]

Actually,that's exactly what the compiler does. The problem occurs in cases like this:

String foo = "";
while (source.hasMoreTokens()) {
foo += source.nextToken();
}

where you are creating a destroying a large number of strings. In this case, using a StringBuffer is far more efficient and doesn't really harm readability.

Re:More efficient != better

[avandesande]

Totally agree. Unless you are doing bioinformatics routines or building multimegabyte docs, you don't need the string buffer. Might as well keep the server busy while you are waiting for that 30ms query to complete.

Re:More efficient != better

[bay43270]

Not only is the first example more readable and better maintainable, but it's much more likely to be optimized in future versions of the JVM (or compiler in the example you point out).

Even before string concatenations were optimized in Java, I used the plus operator. Everyone knew they would optimize it one day, and it really didn't slow anything down enough for anyone to notice (even timed tests had to be run into the millions to see a calculated performance difference in Windows).

By writing around the

Re:The original post is wrong, anyway...

[greenrd]

Anyone who's ever done any performance testing in Java knows that these days, concatinating produces FAR more efficient code than the StringBuffer method...

Rubbish. Concatenating uses stringbuffers. See this post [slashdot.org] for an example of when manually creating stringbuffers is more efficient.

Re:The original post is wrong, anyway...

[tgd]

Um... Not to get into a pissing match, but you've clearly never tried it. Concatinating does NOT create string buffers...

But this is /., heaven forbid anyone try something before they reply, right?

Re:The original post is wrong, anyway...

[tgd]

Well, there are two ways you can prove it -- write a test... do a million iterations of one, versus a million of the other and watch your RAM usage and time it takes. Alternately, compile it and then use a java disassembler, and look at the resulting code. The string concatination is very heavily optimized, and structures like that where you are concatinating hardcoded strings basically does the equivalent of interning them (there aren't real string objects for those). Compilers are smart. If you concati

Who cares?

[Elgon]

Okay,

flippant comment but let's think about this for a second: The majority of the time the alleged efficiency advantage is small or, as is generally the case, a pointless optimisation. Java coders seem to have the major efficiency/speed hangup - they use it to lord it over scripting programmers but they want/lack/desire the swiftness of C. (And yes, I do program in Java.)

To my mind, this is approching the problem from entirely the wrong direction: CPU time and CPU power are far cheaper than developer time and designer time. Therefore, rather than use some cobbled-together hack, use the standard implementations and take the performance hit.

This will be cheaper, probably 95% as efficient and, most importantly, be 195% easier to maintain or change at a later date. Consider the big picture rather than a single aspect.

NB - YMMV, for certain apps, it really does make sense to break all of the above ideas and principles, but if you REALLY need it to run that fast, you should be using C anyway.

Elgon

Re:Who cares?

[dubious9]

Please someone mod this up. I've been trying to say this for years, and perhaps never as eloquently. When you are managing 100K LOC (that's lines of code not library of congress), managers don't care that our programs run three seconds slower, but that they are saving heaps of money in development and maintenance.

Re:Who cares?

[Jord]

True, going back and fine tuning to gain a 2% speed increase (example) is a waste of time. However the value I see in books like this is in training/teaching the developer to write more efficient code the first go around. If you get out of the habit of doing String + String + String and use StringBuffers instead your code is more efficient from the beginning.

That is the value I see from books like this.

Re:Who cares?

[Randolpho]

Perhaps you should pick your examples better. Here's an exerpt from the StringBuffer JavaDoc:

String buffers are used by the compiler to implement the binary string concatenation operator +. For example, the code:

x = "a" + 4 + "c"

is compiled to the equivalent of:

x = new StringBuffer().append( "a" ).append( 4 ).append( "c" ).toString()

Granted, people should get in the habit of coding optimizations automatically, but in this case it's actually more efficient to do String + String + String; it takes less time to code than typing the method calls, and is easier to read/understand.

Which just brings me to my biggest beef about Java: no syntactic sugar. Operator overloading should be a part of Java, and bugger whatever the purists say. I want to save time typing dammit! :)

Re:Who cares?

[evilpenguin]

I used to side with the purists. I've seen operator overloading so badly abused in some C++ programs that it is terrible.

But I recently had to write a Java program that did financial calculations (more rare, even in business software, than you might think). You don't want to use floating point (for all the classic reasons), and, in this case, you don't want to use integers because you need power functions for interest calculations and so forth.

The classic solution appears to be to use the BigDecimal cla

Re:Who cares?

[ReinoutS]

Java would take a huge leap forward in utility if you could just overload the =, +, -, *, and / operators

Perhaps you should take a look at Jython [jython.org]. It's an implementation of Python in Java which allows you to execute Python scripts within Java code or to build Java classes with Python code. Since Python supports operator overloading and has a nice clean syntax it may well be helpful in your situation.

Re:Who cares?

[onash]

And what I don't understand is how we can talk about Java OO-purist when the primitive data types like integers aren't object and needs a wrapper to stick it in a container. That and working with Strings is what I don't like about Java.

I'm pretty sure that a modern compiler should be able to optimize things like that easily by now. If Sun is just holding on to old crap like that just because its old, then Java is doomed to be replaced.

but still I use Java because the IDEs like Eclipse and IntelliJ IDEA ar

why this is inefficient in any case

[Submarine]

The classes of the Java standard library are, by default, thread-safe. This means that all methods that could cause race conditions are synchronized. Unfortunately, unneeded synchronizations are a major performance hit (it depends on the thread implementation).

So, whether you write s1 + s2 + s3 or rewrite this expression using a StringBuffer (which is, anyway, what the compiler does), you incur on most implementations a performance hit because the StringBuffer will be treated as if it could be shared bet

Re:Who cares?

[maraist]

I'm unsatisfied by the idea that hardware is cheaper than developer time. Word Perfect alledgedly attempted to make a version in java, but scrapped it because of speed concerns.

If your product just barely runs within an acceptible time-frame, then you confronted with the probability that a given customer will agree with you. If a customer doesn't agree, then they will not use your product.. Thus while you save money on developer time, you lose potential customers (or existing ones). Worse, late in the g

Re:Who cares?

[plierhead]

Therefore, rather than use some cobbled-together hack, use the standard implementations and take the performance hit.

This will be cheaper, probably 95% as efficient and, most importantly, be 195% easier to maintain or change at a later date. Consider the big picture rather than a single aspect.

Right on. Also, I know there are people out there building client-side Java apps that need blazing UI performance but I'd bet that 80% plus of the Java that gets written is server-side code that probably talks to

Albatrosses

[colin_zr]

Want to kill the albatross?

Ick.

/. editors: please improve your literary references.

The albatross doesn't need killing -- it's already dead. The albatross was hanging from the mariners neck because he had killed it, and by doing so had brought bad luck upon his ship.

Quoting from memory here, because I can't be bothered to go find my copy of the poem:

"God save thee, ancient mariner,
from the fiends that plague thee thus.
Why lookst thou so?" "With my crossbow
I shot the albatross!"

...

Ah

Killing the Albatross

[JahToasted]

isn't killing the albatross what got the ancient mariner into so much trouble?

It's all about the VM

[slagdogg]

I read the first edition of this book completely. There are some good tips for extracting a few percentage points of improved performance. However, nothing has as profound an impact as simply using a better VM ... for example, many of my applications saw 25%+ speed increases simply by switching from the 1.2.x series VM to the 1.3.x series VM. Java does a pretty could job as a language of encouraging best practices, i.e. the inclusion of a standard StringBuffer. Extreme optimization at the code level will always be limited given the high abstraction of the language. However, extreme optimization at the VM level is a very real thing, and it doesn't take a whole lot of effort for the Java programmer.

VMs will not be uniformly better as time goes on..

[alispguru]

The virtue and problem with Java is that it's a virutal machine. A lot of operations that are primitive at the Java byte code level eventually are implemented natively (and differently!) for each different virutal machine. This means that your optimizations for VM X may turn out to be pessimizations for VM Y.

Take threads, for instance - synchronizing primitives are cheap in a Java VM that fakes threads, more expensive in a uniprocessor machine with real threads, and still more expensive in a multi-proces

Java is plenty fast

[ChrisRijk]

I've just been testing with a FFT benchmark I have, where I have both a Java version and a C version. Using GCC 3.2 on Linux, I've yet to be able to build a faster binary than what Sun's 1.4.2 beta JVM can do. IBM's JVMs are generally best at this type of benchmark, though Sun's been catching up fast, quite possibly passed them.

Even with CPU specific optimisations, advanced compiler options etc, the Java version is 30-80% faster than GCC's binary. (this is on both AMD and Intel CPUs) To get anything faster

Re:Java is plenty fast

[be-fan]

The FFT benchmark is a very specific case. Once the JIT kicks in, it's not Java vs C++ anymore, it's the JVM optimizer vs the GCC one. Contrary to popular belief, the GCC optimizer is very good (check out benchmarks vs ICC at coytegulch.com). However, the FFT benchmark is a case where the additional information available to the JIT optimizer allows it to outperform native code. The whole benchmark is so small, it probably even fits in cache, and doesn't really stress any of the performance pitfalls of the language itself. Now, if you have a larger application, that doesn't consist of a single inner-loop, and meanders through a lot of varied code (ie. most real applications) then the performance story will be very different. At that point, Java's performance faults (excessive bookkeeping overhead, object allocation/deallocation, overhead from the JVM, etc) come much more into play.

Re:Java is plenty fast

[ChrisRijk]

The FFT benchmark is a very specific case.

Why? It's smaller than most code, but why does that inherantly benefit Java?

Once the JIT kicks in, it's not Java vs C++ anymore, it's the JVM optimizer vs the GCC one.

That's the whole point. Unless you only care about programs where the entire execution time is a few seconds, the JVM optimisation time isn't going to be much of an issue.

However, the FFT benchmark is a case where the additional information available to the JIT optimizer allows it to outperform

Re:Java is plenty fast

[be-fan]

Why? It's smaller than most code, but why does that inherantly benefit Java?
>>>>>>
The reason it inheretly benefit Java is because of the characteristics of the Java language. First of all, it's a JIT language. Thus, if you have a tight inner loop, the JIT optimizer can optimize the hell out of it (even more so because it has access to runtime information that the static C++ optimizer does not) and just hand it over to the processor for execution. The JVM isn't even executed again until the

Re:Java is plenty fast

[greenrd]

Troll??? The parent post is informative and correct!

Obviously moderated by some moron who thinks that Java is a purely-interpreted language and therefore "can't possibly be faster than C++". I have news for them: Java virtual machines have been compiling down to native code for about five years. GCJ wasn't very original or very clever, and there's no logical reason why it should necessarily produce faster code than a JVM, just because it does its compiling in one go. In fact, there's reason to believe tha

Java performance is second priority for us

[snatchitup]

The bottleneck in our applications is not how fast whatever server-side language we use, and I imagine this is similar is most IT shops.

Our bottleneck is how fast we can execute lots and lots of stored procedures in our SQL and Oracle databases.

It really hasn't mattered if one of our coders has been terminating loops via try{}catch{}, or ending on a condition.

The most important thing has been, "Does each line, each method, each class do what it's actually supposed to do?"

Our bottlenecks have always been flow back and forth between different systems, including Lotus Domino, Oracle, MS SQL Server, Websphere, etc. etc.

Java is a small player in all this... C++, C#, Fortran, Lisp would not speed this up for us.

Re:Java performance is second priority for us

[TheLink]

I'd thought a major bottleneck would be attending all those meetings... :)

Blah blah performance tuning...

[Lardmonster]

So people write their own versions of linked lists and strings, to get up to 15% performance improvement. Well whoopie-fsck.

How much does that extra development time cost?

Writing ones' own java.lang.String takes time. Writing routines to convert com.donkeybollocks.String to java.lang.String and back again takes time. Supporting it takes time. And time is money. Me, I'd rather spend an extra £100 on a faster processor, or a Gb of RAM, and take a 25% performance improvement.

Come on guys, one of the major wins of the OO methodology is code reuse. Time was when programmers would always have to write their own I/O routines - I thought those days were long-gone. Rewriting fundamental parts of the Java API is just plain silly, unless it has a bug or a serious limitation (eg, it's non-threadsafe).

Not a bad albatross

[jemenake]

Performance has been the albatross around Java's neck for a long time..

Every time some C/C++ snob snipes Java for being slow, this is what I tell them:

When I write a Java program... if it's too slow today, then, in time, the problem will go away without any more effort on the part of the programmer. In a year from now, we'll certainly have faster computers, which will make up for any speed problems.

On the other hand...

A year from now, we will almost certainly not have CPUs that are suddenly immune from dangling pointers and memory leaks.

In other words, there are not plausible, near-future-forseeable advancements in computing hardware that could fix the worst problems of C/C++. Meanwhile, the near-future advancements in hardware are almost guranteed to fix Java's worst problem.

The same holds true for doing your computing today... regardless of what hardware is available a year from now. Personally, I'd rather have a slow program that could keep running than one that was really fast, but crashed before I could save my work.

Insightful?

[rfischer]

Remember there is a distinction between client- and server-side Java. Java on the server makes me very happy.

Re:Web pages

[catch23]

Why would the users care whether you use a J2EE or PHP4 backend? You must be thinking of Java applets which very few few people actually use for any "web page development". And the chapters 15-18 that talk about J2EE, what's wrong with using J2EE for the generation of webpages and content?

Insightful!?

[Jerk City Troll]

Java isn't just about applets. In fact, applets are the least used feature of Java -- they're a neat little toy useage. Java is used primarily for back-end code now. Servlets talking to databases, for instance, are where Java is most often found.

Re:Web pages

[msuzio]

People are still using applets? Huh. Didn't know that. Applets are *so* 1996, don't you think? ;-)

Now, on the *server* side, well, Java just plain rocks. Servlets+JSP (when done right, not done moronically and with overuse of EJBs when they aren't needed) is very nice indeed.

Re:Oxymoron ?

[Randolpho]

Amazingly, Java actually performs very well once the JVM loads. Sure, it can't match uber-efficient c code, but, let's be honest here, how much c code really is efficient? I'm sure it's less than c programmers like to believe. ;)

That said, "slow" performing Java GUI aps are not so much the fault of the platform itself as they are the fault of the Java programmer's inability to deal efficiently with threads.

Re:Oxymoron ?

[wfmcwalter]

I don't quite know what it is that they've improved, but JVM startup time seems to have gotten dramatically better somewhere betweek JDK1.3 and JDK1.4.1. On my mainstream winXP machine I can have a text-mode java HelloWorld running to completion in 0.2 secs (tested using cygwin's "time" command). That's a huge improvement over the several seconds it used to take, and makes writing little command line utilities in java a practical prospect.

Previously, the startup slowdown was due to the system having to load, verify, and link the twenty or so classes a simple program depends upon. Pjava and J2ME-CDC solved that by storing an image of the heap with the system classes already loaded, verified, and linked (and quickened) so the system was run-ready almost immediately. I wonder if the J2SE folks picked up on that? Alternatively, they could just be skipping the verify for those classes in the signed rt.jar, and offline preverify them prior to signature - the verifier always was the slow part of the process.

Your point about threads is well taken, and applies more generally to much of java programming. Java's language and libraries make it all to easy to write architecturally-slow programs - you really still have to fully understand what you're doing in order to write a decent program, regardless of the language.

Re:Don't use Java....

[vingilot]

Don't be an idiot. The size of the standard api does not relate to any inefficiency java has. How can the number of standard classes translate to inefficiency What is the magic number of standard classes to be "just right"?
The best thing about java is the richness of the api. And the size of the documentation. C++/C should take a page from java's book in this department.
You don't have to use the standard classes, go ahead and write the classes you need.

Jonathan

Re:Don't use Java....

[be-fan]

Ugh. If C++ took the Java route, alternative operating systems would be impossible. C is so popular because it has a very minimal runtime system. Java is extremely difficult to port because of it's huge runtime. Java and C++ aren't really aimed at the same market. C++ is aimed at systems programming, where people can take the time to find the best external libraries for particular jobs, and need the performance of native code. Java is aimed (right now) at the server market, where having an quickly accessibl

Re:Don't use Java....

[boomgopher]

Java would've been far better if they'd stuck to a few basic classes, and let people develop the classes they need as they go.

Well, gosh, you go right ahead and write your own replacement classes for everything that Sun has done already. What's stopping you?

That's exactly why I like Java. They have a lot of good built-in libraries that cover a wide-range of applications. I don't have to reinvent the freaking wheel every time I write an app.

Re:Sysadmins don't buy into this article.

[markv242]

I forwarded this article to our sysadmins, and they basically laughed it off. At least for web-based applications, almost none of these points apply. The article talks about the author's hatred of JVM startup times (which don't apply for an application server) and exception verbosity (which any real java developer will catch and deal with himself, rather than leaving it up to the sysadmin(?) to deal with).

I challenge you to make a C++/C# application that is thread-safe and can scale to millions of pageviews per day without writing a ton of supporting code. With a good J2EE app server, a java coder essentially just has to wrap his thread-unsafe code in a syncronized() statement, and he's done-- his app is now thread-safe.

Additionally, the "cross-platform doesn't matter for sysadmins" is a false statement; our CIO asked our net ops group "what would be the impact of us moving to an Intel platform?" and our sysadmins (after consulting with the coders) replied "absolutely no impact". That made our CIO very, very happy. Again, I challenge you to move your C++ apps from Solaris to Linux, or even to Windows, without any hiccup.

All of these other arguments are very specious: "I don't have enough RAM" will get you a reply of "go down to Fry's and spend $125 on another GB" every time. Processor speeds, even on Sun boxes, is getting to the point where the processor will never be a bottleneck for anything. Sure, java won't run as fast as a natively-compiled app. Neither will perl, php, tcl, or what have you. Raw processor speed is not as important when you have a couple of GHz to play with.

Re:Sysadmins don't buy into this article.

[markv242]

"You should _always_ try to find the best (or most optimal, I should say) approach/solution to your problem."

I disagree.

You should always try to find the best, most efficient, most cost-effective approach/solution to your problem.

If your internal time is billed out at $50 per hour, and you want to save your company money, you aren't going to spend 4 hours to create a custom garbage collector just to save another 5k of RAM-- you're going to go out and buy another stick of memory.

I agree wrt bad codin

Re:Sysadmins don't buy into this article.

[pmz]

If your internal time is billed out at $50 per hour, and you want to save your company money, you aren't going to spend 4 hours to create a custom garbage collector just to save another 5k of RAM-- you're going to go out and buy another stick of memory.

This reminds me how broken many (most?) corporate accounting systems are. Where I work, for a stick of RAM (or software, or whatever), it would take at least four hours spread over a couple weeks just to figure out who to submit the request to, wait for o

Re:Sysadmins don't buy into this article.

[Bodrius]

I don't know what pletorah of things they taught you in CS school, but much of the wisdom they taught some of us can be summarized:

- Big O matters. Optimization of constants is an expensive luxury.
- Reimplementing the wheel for the sake of marginal efficiency is a sure way to get a square and inefficient wheel.

Most algorithms of any common use are provided in the standard libraries of each language. If not there, any algorithm can be implemented in any language by virtue of its Turing-completeness. This g

Re:Sysadmins don't buy into this article.

[kasperd]

Turing-completeness. This guarantees you bigO efficiency

I agree that bigO efficiency do matter, and you can do that in any half-decent language. But you cannot do efficient programs on a Turing-machine, you will often add a linear factor to the time usage by implementing it on a Turing-machine.

Implementing bubblesort is more complex and expensive than calling Arrays.sort().

Reminds me about the first book I read about assembly code. It started explaining that performance was one of the reasons to wri

Re:Sysadmins don't buy into this article.

[Bodrius]

20% sounds like an inflated number. The typical app spends most of its time waiting for I/O or doing silly stuff for user interaction. A 20% overall difference would imply what, 50%, 100% slower when it's actually working?

There's some overhead, but it's never that bad. Sure, the overhead matters, which is why there's an investment on improving VM technology, providing access to native operations, etc.

But also the worst overhead offenders are not VM issues, but application design issues: blocking I/O, thre

Re:Pre-written appendix for Java Tuning

[egomaniac]

That article is the most absurd joke I have ever read. He spends half the article complaining about Java's startup time (which (A) does not apply in any server situation, and (B) is unfair, because you don't count the machine's bootup time when talking about the performance of C programs, do you?).

Then he invents other ways to talk about the startup time without seeming to talk about the startup time (for instance, trussing Hello World results in a ton of output, but naturally that's Java starting up and loading its classes. Again, do you consider what the machine has to do to boot itself up when you're talking about C programs?). I will point out again that Java's startup time is almost irrelevant, especially in a server environment (which is what he's talking about).

The rest of the article is picking on the "jar" tool. jar is a program written in Java. Criticisms against the jar tool no more reflect on Java than criticisms against gzip reflect on C. The fact that jar doesn't do a good job of reporting errors is (A) irrelevant, because it's a developer tool and we know how to read exceptions, and (B) still more irrelevant, because how well it reports errors has nothing to do with what language it was written in. Tons of C programs have lousy error reporting as well, such as a number of Unix utilities I might name.

Further, this article is obviously very old. He's talking about Java 1.1.8, which is what, five years old now? Might as well criticize Linux by talking about obscure video driver bugs that were fixed five years ago. Obviously, that's not the article's fault for having been written so long ago, but it is the parent poster's fault for bringing it up as if it is somehow still relevant.

Re:Pre-written appendix for Java Tuning

[Admiral Burrito]

Java exception verbosity is a serious problem. Many times I've heard of "java.lang" errors. The correct solution to this problem is to use C-style exception handling:

try {
// code
}
catch (Throwable t) {
System.err.println("segfault");
}

As you can see, Java is every bit as good as C.

Re:Pre-written appendix for Java Tuning

[rutledjw]

You're kidding, right? Who says it's a problem? Heard from whom? Others (like yourself) that don't know java very well?

The exceptions are verbose, yes, but it's hardly a problem. Your example shows a lack of understanding, not of any empirical evidence.

If you like C so well, stick with it. I think that's the best solution

Re:So

[machine of god]

heh. Actually, it got a score of one, because it's in your preferences. You add 1 to people who log in. See, for me, they don't get that. Also, AC's get negative 1 rather than zero. It works out well to weed out people like me and you, I think.

Re:Free Software in Java?

[javahacker]

I guess that means most of the Java programmers out there are busy doing development for money, especially J2EE development.

There are projects out there, just take a look on Sourceforge, but most of them are written to solve problems that Java developers have, not your average user.

In the Windows world, most inexperienced developers use something like VB, which is easy to write flashy, shallow applications in.

On Linux, where most of the Free Software developers hang out, many people have problems with th

Re:Free Software in Java?

[greenrd]

Um... ImageJ (public domain)... also check out http://dmoz.org/Computers/Programming/Languages/Ja va/Applications/