So after some discussion yesterday with a few folks about Exceptions in C++, I decided to add a compilation flag to disable the use of exceptions in tinypyC++.  The claim given to me was around these few items: 1. Exceptions slow your code down.  2. Exceptions aren’t cross-platform (in some cases).  3. Exceptions can easily add in memory-leaks.

I can’t argue with #2, although it’s not completely relevant for the platforms I’m targeting right now.  #3, with the way tinypyC++ does reference counting, I wouldn’t be surprised if this could happen.  #1, I figured might be true, but I wanted to know how real #1 actually was.  So here are my results:

In the first test I’m rendering a Julia fractal for 20 frames and averaging the time it takes to render. In the second test (below) I’m doing the same test, but I did one code optimization to remove a new/delete that was happening for each pixel – by reusing the coordinates object.

I found it interesting that in the 2nd test case I did, removing exceptions actually increased the time it took to render the fractal!  Not quite sure why .. hmmm.  (I tried it a few times and kept getting similar results too.)

What is clear in the second test is that the compiler is able to optimize the code much more aggressively.  I guess Exceptions choke up the optimizer.  In all cases it seems that adding on the -g flag seems to make the code run slightly faster, surprisingly enough!  (-g adds in debugger info.)  In all cases, the optimizer was able to roughly double the speed of the program, and when I disable exceptions it is able to throw in even more speed.

-Phil

This entry was posted on Wednesday, January 6th, 2010 at 6:26 pm and is filed under C++, development, tinypy. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.