Feature or enhancement

An API similar to:

/* Visit all live GC-capable objects, similar to gc.get_objects(None).** Users should avoid allocating or deallocating objects on the Python heap in* the callback. */typedef void (*gcvisitobjects_t)(PyObject *, void *);PyAPI_FUNC(void) PyGC_VisitObjects(gcvisitobjects_t callback, void *arg);

Which could be used as:

void count_functions(PyObject *op, void *arg) {  if (PyFunction_Check(op)) {    (*(int*)arg)++;  }}int get_num_functions() {  int count;  PyGC_VisitObjects(count_functions, &count);  return count;}

Pitch

We have a version of this inCinder already and right now and use it toidentify all generator objects so they can be de-opted when our JIT is shutdown. In future we plan to use it for things like discovering existing PyFunction objects, and then usinggh-91049 to mark them as JIT’able. This could facilitate loading the JIT feature at a later time (e.g. as part of a module).

[Edited] In general, there already exists a Python API for iterating over GC’able objects viagc.get_objects(), however there is no good way of doing this from native extensions. While it is technically possible to import thegc module and extract thegc_objects function in C this is cumbersome, and more importantly might lead to unexpected behavior if Python code has replaced thegc_objects function.

Linked PRs

• gh-102013: Add PyUnstable_GC_VisitObjects #102014
• gh-102013: Move PyUnstable_GC_VisitObjects() to Include/cpython/objim… #115560