Historically (Python 2.x) it had a bunch of caches in front of actual system malloc. And that was (is?) reasonable with glibc default malloc being the very bad

Historically (Python 2.x) it had a bunch of caches in front of actual system malloc. And that was (is?) reasonable with glibc default malloc being the very bad dlmalloc. (This plays hell on things like Valgrind or ASAN.)