Re: [udig-devel] Adding layers to existing map is slow

[Jody Garnett <jody.garnett@xxxxxxxxx>]

On Sunday, 4 December 2011 at 12:21 AM, Milind Suley wrote:

No. Have not opened issue on JIRA for this. Should i?

We try and create a JIRA issue for all issues we are tracking. As sometimes it is a while between a problem being reported and anyone having funding to work on a fix. You could also make a wiki page; and then link to issues that come up during optimisation?

You are also starting to record good measurements to help isolate the problem; it would be good to write that down so it is not lost. 

Thanks for your

earlier suggestions.

They were not very good suggestions; only wondering out loud what the problem could be.  

Am trying to interpret your suggestions in terms

of code changes.

It is too soon to consider code changes; the next step would be to use a profiler to confirm where the problem is. Changing code in the hopes of making an improvement (while entertaining) is not really very scientific :-)

The general approach for any performance problems is:

1. Measure a baseline - you have this. We may want to test with some sample data others can see so that they can reproduce your results if needed. Depends on how much of the work you are doing yourself. You may end up with a number of things you want to measure; some thought into setup can really help isolate problems

2. Set a performance goal - so you know when to stop. Do you have any performance targets in mind here?

3. Run in a profiler to determine where the application is spending its time

4. For each "hot spot" identified

a) go through why the application is spending its time; identify an optimisation technique; apply ...

b) measure the improvement; if it is not a significant improvement it is not worth changing the code

5. Repeat step 4 until performance target (or budget) is met

I am afraid my early email assumed you were correct about event notification being a problem; discussed a couple ways to take charge of event notification. The problem could just as easily be many redraw request made in response to perfectly good event notification ...

Jesse would be able to offer some better advice; let us ask when a profiler has been used.

Can I ask if you have used a profiler before? Java does come with one out of the box; we have an arrangement with http://www.yourkit.com/ for open source work so a lot of the projects I work on end up using that.

Jody