Re: [amsat-bb] MARS rise & set times

[Margaret Leber <maggie@xxxxxxxxxxxx>]

Phil Karn wrote:

> By the way, on OS X at least Mars24 burns an awful lot of CPU time for 
> what it does, about 34% of a 2 GHz G5. Probably because it's written in 
> Java, a remarkably inefficient language.

Tsk,tsk,tsk. Modern Java runtimes (the only kind there are on OSX) often 
  compare very favorably with handcoded C for many operations, apples to 
apples.

See http://kano.net/javabench/index (warning: rude page heading)

Unfortunately, while it's not *quite* as easy to write bad Java as it is 
to write bad C, it's still very possible. The probability of writing bad 
GUI code is higher, mostly because Java does a lot of extra work to be 
portable across all the various GUI platform possibilties out there. 
This may have something to do with why running the "solar plot" display 
(not exactly graphically intensive) pegs my CPU to 100% on both the 
browser applet and application versions.

I can confirrm about 60% CPU utilization for Mars24 application on my 
elderly 700 MHz Pentium III running an equally elderly copy of Linux. 
For a somewhat slower start-up but improved long-run performance specify 
the "server version" of the Java virtual machine (command: "java -server 
-jar Mars24.jar"); on my system this gives someting around 36-40% CPU 
utilization once the application is started and running. The server 
version of the Hotspot JVM also drastically reduces the "solar plot" 
display CPU usage.

Of course, these numbers would surely be different if C were used; 
there'd probably be one somewhat better-performing version for whatever 
platform the developer had at-hand (SPARC?), and everybody else 
(including you and me, Phil) would see 0% utilization because there 
wouldn't be a version for their Windows, OSX and Linux machines, nor 
anything runnable in web browsers. :-)

  73 de Maggie K3XS

-- 
-----/___.   _)Margaret Stephanie Leber CCP, SCJP/"The art of progress /
----/(, /|  /| http://voicenet.com/~maggie SCWCD/ is to preserve order/
---/   / | / |  _   _   _    `  _  AOPA 925383/ amid change and to  /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_      K3XS / preserve change amid/
-/ (_/   '        .-/ .-/        ARRL 39280 /order."-A.N.Whitehead/
/________________(_/_(_/_______AMSAT 32844_/<maggie@voicenet.com>/


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