[Python-Dev] Optimization targets - refcount (original) (raw)

Paul Prescod paul at prescod.net
Fri Apr 16 02:11:00 EDT 2004

Jewett, Jim J wrote:

Mike Pall:

About GC: yes, refcounting is the silent killer. ... PyDECREF is awful ... > 3500 locations Is it always needed? What if a few common (constant, singleton) objects (such as None, -1, 0, 1) were declared immortal at compile-time? They would be created at initial load in a special untracked pool, and their tpdealloc would do nothing. The slot for tracking references would still be there, but could be ignored -- even if it went negative. Since the reference count no longer has to be correct (for these objects), the reference counting macros could optimize to nothing when they know at compile time that they'll have one of these constant objects.

So instead of writing Py_DECREF(foo) would we write code like

if(foo!=Py_None&&foo!=Py_Neg1&&foo!=Py_Zero&&foo!=PyOne){ Py_DECREF(foo); }

Paul Prescod

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