Basic Parallel Programming Questions
Basic Parallel Programming Questions
I have a mapping application which does a TranparentBlt to combine several bitmap layers (e.g. roads, towns, state borders etc) to create the map. Rendering each layer takes time, so I thought this would be a wonderful task for the new Parallel library in XE7. It's a simple For loop to go though each layer and call "Render", but for some reason the parallel version misses details on the map. Then I find when I set breakpoints in the code to executed in the for loop, they don't fire!
So my questions are:
1. Is there anything you shouldn't do in a parallel for-loop? I'm creating independent bitmaps (i.e. each one is not dependent upon any other), so I wouldn't have thought I need to "lock" anything. Am I correct?
2. I assume a parallel for-loop waits for everything to be executed before continuing execution of the code. Is this correct? Or are we just firing off a loop of tasks to complete and continuing the execution of the code?
3. If you can't set breakpoints in parallel code, how do you debug it? Any tips appreciated!
Steve
I have a mapping application which does a TranparentBlt to combine several bitmap layers (e.g. roads, towns, state borders etc) to create the map. Rendering each layer takes time, so I thought this would be a wonderful task for the new Parallel library in XE7. It's a simple For loop to go though each layer and call "Render", but for some reason the parallel version misses details on the map. Then I find when I set breakpoints in the code to executed in the for loop, they don't fire!
So my questions are:
1. Is there anything you shouldn't do in a parallel for-loop? I'm creating independent bitmaps (i.e. each one is not dependent upon any other), so I wouldn't have thought I need to "lock" anything. Am I correct?
2. I assume a parallel for-loop waits for everything to be executed before continuing execution of the code. Is this correct? Or are we just firing off a loop of tasks to complete and continuing the execution of the code?
3. If you can't set breakpoints in parallel code, how do you debug it? Any tips appreciated!
Steve
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