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How do I start optimising my Java code? - CPU is at 100%

Answer 1

+6 A:

The problem doesn't seem to be in the methods which are being used a lot, it's how frequently you call them which appears to be why they are showing up so frequently. I'd check for all of the calls, see if any are superfluous then go to the third most time consuming method. After that, I would check my algorithms for being particularly intensive. Also, check all method calls and make sure they're not being run without need.

I know this isn't solving the problem itself, but its a start with the information given.

EDIT: The while loop is an infinite loop causing a for loop to run in which every item in an array has been checked to see if its been reset. You can replace this with an observer pattern where when an object is reset, it notifies the observing object which then performs that set of steps. This way you don't have an infinite loop and you cut down on the usage of .isReset(). This is in the main method of Class 1.

Edit 2: Here's the example of an implementation of the observer pattern which is on wikipedia.

indyK1ng 2009-06-23 23:39:47

+1 - More than a start, this is the correct way to approach the problem.

Tom Leys 2009-06-23 23:45:52

+1 - Thanks for that answer, and I'm not the OP.

karim79 2009-06-24 00:03:48

thanks man, good advice :)

ferronrsmith 2009-06-24 00:17:41

Is it possible for you to show an example of this please?

ferronrsmith 2009-06-24 02:02:23

Here is an image of the data that was collected after i profile the application: http://farm4.static.flickr.com/3375/3655986078_27ba7cbd07_o.png

ferronrsmith 2009-06-24 02:05:02

Answer 2

+2 A:

Start with the most intensively used method in your readout and move to less and less intense methods until you find one with a loop construct (for, while). Check the loop construct to see if it is doing too much work, and see if the functions that call this function call it often.

i.e (pseudocode)

dotProduct(vector a, vector b)
{
  //create vector dot product here
  maths maths maths
}

calc(data)
{
  for obj in data:
    dotproduct(obj, foo)
}

dotProduct will use the most CPU time, but calc is the place to start - can we cache results? are we recalculating data? Are we iterating through data in a stupid way?

Tom Leys 2009-06-23 23:49:29

Answer 3

+2 A:

"How do I start optimising my Java code?"

You start by profiling it first.

Alex B 2009-06-23 23:53:54

quote "I ran a profile r on a few of the classes and a report show that isReset() and isRunning() seems to be called alot of times. Do you see anything wrong please inform me. thanks"

ferronrsmith 2009-06-24 00:16:30

A decent profiler will highlight "hot spots" in the code, and allow you to follow the call traces upwards, showing you which methods are calling the hot methods. You can do all of this manually, too, but finding a good profiler is well worth the time invested in the investigation.

Bill Michell 2009-06-24 08:57:20

Answer 4

A:

First things first. you have a warning in you code somewhere, as that you have used the annotation

@SuppressWarnings("serial")

. While this very well may have nothing to with your cpu maxing out. Fix this first and you very well may stumble on the problem.

WolfmanDragon 2009-06-24 00:15:32

Answer 5

+1 A:

Judging by the function names "isReset()" and "isRunning()" being called a lot, I would guess that you're wasting CPU time polling for a condition/event. Java should have some sort of semaphore/signalling system that you can use to let the do-er notify the wait-er exactly when the event occurs.

Andrew Medico 2009-06-24 00:41:27

That's what I thought. Probably just a loop waiting for isReset to return true.

scottm 2009-06-24 00:51:23

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How do I start optimising my Java code? - CPU is at 100%

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