GCJ, a quest for speed.

[erikd]

Heh, HelloWorld is now 4.6MB.  

Other than some really trivial things, I couldn't get anything to compile and run correctly. Some test programs required some hacks to get it to compile.
For example for doing a quick and dirty new Date().toString(), I finally had to add 2 static references to gnu.java.locale.Calendar.class and gnu.java.locale.LocaleInformation.class in my source, which is a bit weird  . The little test program BTW is a simple socket that returns the time, but the GCJ version compiles and runs (after inserting the extra lines of dummy code), but behaves differently (I couldn't test the response from the socket using a browser where I can with the java version).

If I can't even get these miserable 50 lines of code running, I won't even bother with compiling a LWJGL program.

Using GCJ is certainly no walk in the field  .

I'm not giving up just yet, but so far no result at all.

[SpongeBob]

Heh, HelloWorld is now 4.6MB.  

Thats pretty good figuring a simple HelloWorld in regular java is over 30MB is size.

Now some of you are thinking that I must be crazy BUT you may be forgetting that a GCJ compiled program includes a Java runtime.  So, add the size of your JRE with any java app you write to figure the size in comparison.

There is a DLL you can link your GCJ programs to for Windows that takes out the java runtime fat (Google for libgcj.dll).  Thats nice if you are planning on having multiple GCJ apps on the same system.

Also, check out UPX (upx.sf.net).  Use it to deflate GCJ apps.

upx --best HelloWorld.exe

Some test programs required some hacks to get it to compile.
For example for doing a quick and dirty new Date().toString(), I finally had to add 2 static references to gnu.java.locale.Calendar.class

Yes, this is a known issue.  But its the only oddity I have ever seen.  What other problems are you having?

If I can't even get these miserable 50 lines of code running, I won't even bother with compiling a LWJGL program.

Post your code.  I curious to whats going wrong.

[erikd]

Here's my test:

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import java.io.IOException; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; import java.util.Date; /**  * TServer.java  */ public class TServer {         private static final Class class1 = gnu.java.locale.Calendar.class;         private static final Class class2 = gnu.java.locale.LocaleInformation.class;         int port;         public TServer(int port) {                 this.port = port;         }         public void run() {         boolean waiting = true;         ServerSocket serverSocket = null;         try {             serverSocket = new ServerSocket(port);         } catch (IOException e) {             System.err.println("Could not listen on port: " + port);             System.exit(1);         }         while (waiting) {                 Socket clientSocket = null;                 System.out.println("Waiting for request");                 try {                     clientSocket = serverSocket.accept();                 } catch (IOException e) {                     System.err.println("Accept failed.");                 }                 PrintWriter out = null;                         try {                                 out = new PrintWriter(clientSocket.getOutputStream(), true);                         } catch (IOException e) {                                 System.err.println("Error getting PrintWriter:" + e);                         }                 out.println(new Date().toString());                 out.close();                 try {                                 clientSocket.close();                         } catch (IOException e) {                         }         }         try {                         serverSocket.close();                 } catch (IOException e) {                 }         }     public static void main(String[] args) throws IOException {         if (args.length != 1) {                 System.out.println("Usage: TServer [port]");                 System.exit(1);         }         TServer t = new TServer(Integer.parseInt(args[0]));         t.run();     } }

Games published by our own members! Check 'em out!

[erikd]

Quote:
Heh, HelloWorld is now 4.6MB.    


Thats pretty good figuring a simple HelloWorld in regular java is over 30MB is size.

Now some of you are thinking that I must be crazy BUT you may be forgetting that a GCJ compiled program includes a Java runtime.  So, add the size of your JRE with any java app you write to figure the size in comparison.

Yes, you're absolutely right but downloading a runtime with every GCJ app makes a one time download of a more functional JRE look more attractive still.

I'm still interested in getting GCJ to compile my LWJGL stuff, but it will be of very limited use: To make a one time download of the game or game demo a bit smaller and easier.
I did some more tests and there seems to be no speed gain with GCJ. For example the 'ArrayTest' code from the http://www.java-gaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=Tuning;action=display;num=1065650709 thread is a tiny bit slower in GCJ compiled form than running the java code in the 1.4.1 client VM.

Erik

[Woz]

I didn't have that much trouble getting hello world down to < 500K.

You've just got to use lots of GCC switches!

Page 2 of this topic has the correct switches listed to get < 500K.

They are supposed to be doing something about the size in GCJ V3.4 but how much difference it will make is another matter - bearing in mind that you have to provide the functionality of the JVM and the compiled code in order for it to execute properly.

Jacko points out that a preview of 3.4 is available from the http://www.thisiscool.com/gcc_mingw.htm but whether that includes the size modifier I don't know. Neither have I been able to try it yet due to an annoying combination of zero time and a hard drive failure.

As to the array speed test, this does not surprise me but did you try it with the Array Bound Checking switched off in GCJ?

The simple fact is that the array fill is compiling into exactly what it has been asked to be. Which is not particully optimal for execution speed on the cpu and memory subsystem. This is a problem of it looking fast to humans, but not being fast for a cpu. For example I would not use that code in C (other than for easy of use that is [read laziness  ]).

There has been a lot of success with GCJ and SWT, for example Eclipse has been successfully compile, which is hardly a small product.

Hopefully using GCJ will become easier.

-------
Woz.

[erikd]

I didn't have that much trouble getting hello world down to < 500K.

You've just got to use lots of GCC switches!

Page 2 of this topic has the correct switches listed to get < 500K.

Yes, I'm aware of the GCC switches and upx and all to shrink the executable. I'm not too worried about all that. The reason I mentioned the straight helloworld example is now 4.6MB, was just an observation that the helloworld.exe went from 2.6 to 4.6MB as of GCJ 3.4.

but did you try it with the Array Bound Checking switched off in GCJ?

*blush* er I'm afraid not until just now:
The GCJ version is not ~13% faster than the client VM version and still 5% faster than the server VM version (wasn't the server VM supposed to eliminate bounds checks too?).
That's very good indeed.