[Python-Dev] gc ideas -- dynamic profiling (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Sat Dec 4 00:21:52 CET 2010

q1 are generations placed in separate memory regions, or are all generations in one memory regions and there is a pointer that signifies the boundary between generations?

You should really start reading the source code. See Modules/gcmodule.c.

To answer your question: neither, nor. All objects are in one region, and there is no pointer separating the generations. Instead, all objects belonging to one generation form a double-linked list.

I propose to track hot spots in python, that is contexts where most of allocations occur, and instrument these with counters that essentially tell how often an object generated here ends up killed in ephemeral, short-, long-lived garbage collector run or is in fac tstill alive. If a particular allocation context creates objects that are likely to be long-lived, allocator could skip frst 2 generations altogether (generations are separate regions) or preload the object with high survival count (if q1 is single region).

We would consider such a proposal only if you had actual evidence that it improves things, rather than just having a reasoning that it might.

Regards, Martin

More information about the Python-Dev mailing list