As I can see here https://github.com/python/devguide/blob/master/garbage_collector.rst#collecting-the-oldest-generation

> the GC only triggers a full collection of the oldest generation if the ratio long_lived_pending / long_lived_total is above a given value (hardwired to 25%)

But in the python docs here https://docs.python.org/3.10/library/gc.html#gc.set_threshold

> When the number of allocations minus the number of deallocations exceeds threshold0, collection starts. Initially only generation 0 is examined. If generation 0 has been examined more than threshold1 times since generation 1 has been examined, then generation 1 is examined as well. Similarly, threshold2 controls the number of collections of generation 1 before collecting generation 2.

As I can see here: https://github.com/python/cpython/blob/master/Modules/gcmodule.c#L1456 the first one is correct.

We should probably fix python docs accordingly.