On 11/24/2011 9:27 AM, Dave Angel wrote:
...
Several ways to speed up code.
1) use language features to best advantage
2) use 3rd party libraries that do certain things well
3) use best algorithms, subject to #1 and #2
4) have someone else review the code (perhaps on the list, perhaps
within your own organization)
5) measure (eg. profile it)
6) use optimizing tools, such as pypy or Cython.
7) rewrite parts of it in another language
8) get a faster processor
9) rewrite it all in another language
It takes experience to choose between these, and each project is
different. But even the most experienced developers will frequently
guess entirely wrong where the bottleneck is, which is why you measure
if you care.
I agree that measuring (profiling) is the most critical.
As you say, even the most experienced programmers can guess wrong. The
first time I used a profiler a couple of decades ago I was egotistical
enough to wonder how this thing could help me. After all, I wrote the
code. I knew what it did. The profiler wasn't going to tell me
anything I didn't know.
I learned a little humility after reading the profiler output. The
program was spending most of its time in a place that I never dreamed
was a problem, and a 10 minute fix cut run times in half.
In that particular case there wasn't even a design problem, it was just
a procedure call inside a tight loop that executed far more often than I
imagined and could be replaced with a few lines of inline code.
I think the rest of your list is excellent too.
Alan
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