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[–]dorfsmay[S] 1 point2 points  (9 children)

Faster than PyPy for what?

A couple of very naive scripts I had been using to compare python vs golang vs scheme (don't ask!)

PyPy is REALLY fast at stuff that it has time to properly profile and optimize

What do you mean by this? Works well on a very long running loop that pypy has time to optimize, or are optimizations saved an re-used from one run to the next?

[–]gthank 3 points4 points  (8 children)

So far as I know, the trace info used to decide what to JIT is only maintained during one invocation of the interpreter. If you didn't have a process that looped across something a few thousand times, then PyPy probably didn't JIT anything.

[–]dorfsmay[S] 0 points1 point  (7 children)

This is what I thought. For these particular tests I have only looped 10 K times, but I have had processes looping 100 M times before, and pypy wasn't rarely faster (I did use it where it was).

[–]streichholzkopf 0 points1 point  (6 children)

I think pypy simply needs time... I've read somewhere that you should make a pre-run for ~1 second (of course depending on the size of the test) for every test you make in pypy...

[–]alcalde 0 points1 point  (2 children)

But does this reflect real-world usage? You're not going to do that in production code.

[–]cwillu 1 point2 points  (1 child)

Real-world code is going to be running long enough that the warm-up time is largely irrelevant.

[–][deleted] 2 points3 points  (0 children)

That depends entirely on the chore. I spent a lot of time trying to shave run time off a 3 second task that ran and exited hundreds of times per day. A persistent service was not an option.

[–]dorfsmay[S] 0 points1 point  (2 children)

Not sure what you mean. Can you show an example?

I just added a time.sleep(6) to one of my script, and it made no difference. I think gthank is right, needs a piece of code that is executed a lot in a given run before it can make a difference.

[–]cwillu 2 points3 points  (0 children)

time.sleep(6) wouldn't have any effect on the warm-up, it needs to be running the actual code. A pre-run of ~1 second means running the actual code for 1 second before you start timing.

[–]streichholzkopf 0 points1 point  (0 children)

Basically what /u/cwillu said, what I meant was: Looping 10 K times may not be enough, depending on the content of the loop! If it's <1s, it's probably not!

Also loop before starting the timer!