Issue 3029: free list management - list, dict, set (original) (raw)

Freelist clearing functions for int and float were added by Christian, and made available to Python code via a function in the sys module. I don't know who added the freelist clearing functions for the class, frame, method, tuple and unicode objects, but they are called by gc.collect().

Because the freelist implementations are all static to the relevant type source files, functions within each object source file seem a reasonable way of implementing the required functionality.

I don't see the need for them to be part of the public API, but I framed this patch to fit in with what's already in place.

It is likely that the functionality of this patch is of minor value, and can thus be rejected.

Indeed, I experimented with ripping out all freelists and making sure that all types used PyMalloc, and the resulting interpreter is about 6-8% slower on a pybench run (FreeBSD 7.0, gcc 4.2.1, 6% slower on 32bit, 8% slower on 64bit, 64bit is ~15% faster than 32bit in either case) than the trunk (r63501). Individual micro-benchmarks in pybench show 15-30% variations between the freelist & no freelist, but this doesn't seem to significantly affect the running of the whole benchmark.

Issue 2862 is more important IMO, as the current situation has 2 different approaches to accessing freelist management, where I believe there should only be 1.

I don't see the need for them to be part of the public API, but I framed this patch to fit in with what's already in place.

These should not be part of the public API; otherwise, we lock-in the freelisting implementation detail and cannot readily change it (since some C code may come to rely on the new functions).