Why is a Python Lambda wildly slower than a Javascript Lambda with the same functionality?

Question

I am creating a sorting comparison workbench using AWS to host sorting lambdas.

I have a bubble sort algorithm implemented in python (python3.8) and javascript (nodejs12.x) lambdas. Both have 512MB memory allocated.

When I run these against eachother with array lengths N of 1 to 5500 I get the following graph. N is on the x axis and time taken in MS on the y axis:

While I expect bubble sort to be slow, I didn't expect Python to be 100x slower compared with Javascript. The max milliseconds reached for JS is ~120, vs Python at ~11100.

Perhaps there is an AWS related explanation, or my implementation is very slow?

Update: I switched the runtime over from CPython to PyPy and this has reduced the time by x100 for running bubble sort, the graphs are now much closer together, thus the time difference was due to the compiler:

question from:https://stackoverflow.com/questions/66053519/why-is-a-python-lambda-wildly-slower-than-a-javascript-lambda-with-the-same-func

Answer 1

cpython and node differ in how the code is interpreted:

• Python (the standard cpython) is compiled to bytecode and then interpreted. So the interpreter spends most of it's time in a loop containing a big switch-case. (See https://github.com/python/cpython/blob/5f18c223391eef8c7d01241b51a7b2429609dd84/Python/ceval.c#L1622)

• node.js (using V8) and PyPy use just in time compilation. This kind of Problem (tight loop, homogeneous types) is what JITs are best at: if the interpreter sees that some piece of code is run very often with the same types, the JIT generates and optimizes native code for it.