On Tue, Jun 23, 2015 at 9:01 AM Barry Warsaw <barry@python.org> wrote:
On Jun 23, 2015, at 01:52 PM, Nick Coghlan wrote:
The current reference-counts-embedded-in-the-object-structs memory layout also plays havoc with the all-or-nothing page level copy-on-write semantics used by the fork() syscall at the operating system layer, so some of the ideas we've been considering (specifically, those related to moving the reference counter bookkeeping out of the object structs themselves) would potentially help with that as well (but would also have other hard to predict performance consequences).
A crazy offshoot idea would be something like Emacs' unexec, where during the build process you could preload a bunch of always-used immutable modules, then freeze the state in such a way that starting up again later would be much faster, because the imports (and probably more importantly, the searching) could be avoided.
I actually would like something like this for Python, but I want it to work with hash randomization rather than freezing a single fixed hash seed. That means you'd need to record the location of all hash tables and cached hashes and fix them up after loading such a binary image at process start time, much like processing relocations when loading a binary executable. Non trivial. -gps