Issue2738

Hi, 

Just to draw your attention: There is a discussion thread about some problems with Jython https://stackoverflow.com/questions/54281767/benchmarking-java-groovy-jython-and-python/54326863

i.e. certain calculations cannot be done due to very slow execution.
I do not know, is this a feature or a bug. Why other scripting languages (such as Groovy) are so fast? Can this point to some problems in the Jython core?

Yes, it is slow for this scenario, at x10 slower as seen here. Jython and CPython should currently be at about the same speed, since they have very close implementations. I did find it interesting that JRuby had very similar performance, which shows how challenging speeding dynamically typed languages is.

There is however one thing that makes things unnecessarily slow: because Jython 2.7 implements the Python 2.7 language, the code should be written to use xrange, not range, which will allocate a list containing 100 million consecutive integers. That's obviously unnecessary overhead.

It is also possible that we can still improve this speed with InvokeDynamic and related support, but that's a hard engineering challenge, even with the improvements in this support in JDK 12.

Hi, Jim

 Thanks! I see that the stackoverlow has been already corrected with range()->xrange() for the Jython example. Now it's  much better (40 sec) than it was with "range()". Still, not clear why Groovy is super-fast.

best

Not a bug, but just a free "visionary" idea where to go with Jython
(after reading again the thread https://stackoverflow.com/questions/54281767/benchmarking-java-groovy-jython-and-python/ )

If Jython will be as fast as Groovy then Jython may easily dwarf CPython in popularity.  This will be a very strong selling point for Jython, and will attract many developers. But one needs to learn what is under the hood of  Groovy/JRuby. Of course, this is a lot of work, but this can be very promising direction.

Adjusting the priority here so that, if ever we produce a Jython with decent performance for arithmetic (and who wouldn't want that?), we have this to hand. Taking off the 2.7.1 though.