I think rather than hardware specs would be good to see the code that is freezing it :-)

It is the right place if you show your code. The hardware shouldn't be important, but if you have an error in your code, it might explain such freeze.

Here is the code:

The code as posted will not freeze your laptop but it will give a black screen. The reason is that the black lines you are drawing completely fill the drawing area so it appears as if nothing has happened.


I have modified your code slightly - try this code and it should make it clearer.

1. void setup()
2. {
3.   size(640, 480);
4. }
5. 
   
6. void draw()
7. {
8.   background(255);
9.   stroke(0);
10.   for (int x=1; x < 640; x+=10)
11.     for (int y=1;y < 480;y+=10)
12.       line(0, 0, x, y);
13. }

> The code as posted will not freeze your laptop

it could easily hit 100% cpu which would look like a freeze, especially on a single core processor.

Yes, kooogy, but it is unlikely on an i7 processor...

Hi Guys,

Please note I tried the same nested loops in C++, VB , VB.NET, C#  programming languages on the same machine it executed in a blink. Then I tried the nested loops in Java applet, just to make sure that JVM is working fine.
It runs perfectly.

My only concern is that if nested loops is not working properly, how can I scan 2D array in processing or read the pixel values from the screen or the image in memory. I tried both processing version 1.5 and 2.08a on 32 and 64 bit, using Windows 7.

However, I'll give a try to Quark code, though I don't want to skip the values especially when you are reading pixel or arrays values.

Thanks for your time to reply and feedback.

Your expert comments are always welcome.

Saad

It is running fine here. Mac/osx10.8/ java SE 6/ processing 1.5.1.

Your test is a bit meaningless... You say you tried the loops in other programming languages, but are you aware that draw() is run periodically? At best (by default) 60 times per seconds. It is different from a simple nested loop in VB, unless you try it in a similar framework.
And "my laptop freezes" is a subjective measure. Do you looked at the CPU usage while running your sketch? Mine tops around 25% on a quad-core (AMD Athlon II).

Here is a variant of your test:

1. void setup()
2. {
3.   size(640, 480);
4. }
5.  
6. void draw()
7. {
8.   for (int x = 0; x < 640; x++) // Note that arrays start at 0!
   
9.   {
10.     for (int y = 0; y < 480; y++)
11.     {
12.       color c = color(random(255), random(255), random(255));
13.       set(x, y, c);
14.     }
15.   }
16.   if (frameCount % 10 == 0) println(frameRate);
17. }

On my computer, it runs around 33 frames per second and the Java process uses 24 % of CPU (on all cores).
A more efficient version is:

1. void setup()
2. {
3.   size(640, 480);
4. }
5. 
   
6. void draw()
7. {
8.   loadPixels();
9.   for (int x = 0; x < 640; x++)
10.   {
11.     for (int y = 0; y < 480; y++)
12.     {
13.       color c = color(random(255), random(255), random(255));
14.       pixels[x + width * y] = c;
15.     }
16.   }
17.   updatePixels();
18.   if (frameCount % 10 == 0) println(frameRate);
19. }

and it runs at 38 fps, with 27 % of CPU usage.

You see, I don't have a beast of computer (perhaps equivalent to a i5), and it is far from freezing.

In my case CPU usage was never exceeded from 13% which is I believe acceptable for many of us. However, I figure-out that the problem lies with frameRate and draw() functions. What I did to resolve my problem, I reduce the frame rate from 60 to 30 and the same code is working fine. At this time CPU usage dropped to 5%. 

This test runs at 61 fps using abput 112% of cpu in my macbook 2.8 intel core 2 duo

That's odd, because it runs on my pc at 80 fps, with a CPU load of 60-70%. I run on a Intel core 2 duo 2.4 Ghz. Perhaps it is the videocard that can give a problem.

Hi El_dippo