hi

I am starting to experience performance issues with my applet and I'm nowhere near adding all the forces of the fully implemented version - this one is just to get the behaviour right.

http://upsdn.ca/processing/hairplay02d/applet

It is a particle system - each point along the perimeter of a circle is connected to every other one, along the lengthg of this connection, new particles are added, connected by springs. I have other questions about this sketch but for now I can't do anythng until I sort out ways to make it run smoother...

thanks

I haven't spent much time on it but a few things stand out.

Try to avoid declarations inside loops. This adds extra stuff that Java has to do.

You have several loops in the draw method. If you can (again, haven't looked to closely) try to do several things during the same loop:

i.e.
Code:

Particle p;//declare variable p
for (int i=0; i<largestArray.length; i++) {
  p = aParticle;
  if (i < arrayA.length) //do something with arrayA;
  if (i < arrayB.length) //do something with arrayB;
  ...
}
 

If you know that nothing will be added/removed from an ArrayList , you can store the result of arrayList.size() into a variable. This will reduce the number of function calls.

Also, if you know the type and number of objects you are working with, you could simply use an array of that object. ArrayLists are faster than Vectors, but there is still an added function call to get().

Smooth() can slow things down too, using P2D or P3D may help.

A lot of objects means lots of memory usage. Every reference to an object requires 8 bytes by itself.
The internal array of an ArrayList will typically be larger than the number of objects that you have added which means they often take a little extra.

One more thing I found was the println("on") and println("off").
Printing to the console repeatedly can drag down a program.

Slowly looking...

Is that true for objects as well as primitives?

NoahBuddy wrote on May 7^th, 2009, 10:49am:

Actually, your p variable is a kind of primitive, just a reference (a pointer in C talk) to the real object.

I just found back one of the articles I mentioned: Myth - Defining loop variables inside the loop is bad for performance.

This is interesting. Takes longer even if the variable is defined outside the loop.

Code:

final int COUNTS = 20000000;
long mils=0;
Integer a = (int)random(512);
Integer g=10;

mils = System.currentTimeMillis();
for (int i=0; i<COUNTS; i++) {
  g = 2*a;
}
println(System.currentTimeMillis() - mils);
  
mils = System.currentTimeMillis();
for (int i=0; i<COUNTS; i++) {
  Integer f = 2*a;
}
println(System.currentTimeMillis() - mils);
 

Edit: By the way, changing 'Integer' to 'int' brings the times to about the same.