[Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered (original) (raw)

INADA Naoki songofacandy at gmail.com
Tue Sep 20 07:11:52 EDT 2016

On Tue, Sep 20, 2016 at 7:02 PM, INADA Naoki <songofacandy at gmail.com> wrote:

On Tue, Sep 20, 2016 at 6:56 PM, Dima Tisnek <dimaqq at gmail.com> wrote:

Totally random thought:

Can lrucache be simplified to use an ordered dict instead of dict + linked list? I think so. See also: http://bugs.python.org/issue28199#msg276938

FYI, current dict implementation is not optimized for removing first item like this:

// When hit max_size
Py_ssize_t pos;
PyObject *key;
if (PyDict_Next(d, &pos, &key, NULL)) {
    if (PyDict_DelItem(key) < 0) {
        // error.
    }
}

So, before changing lru_cache implementation, I (or someone else) should rewrite OrderedDict which has O(1) "remove first item" method. (At least max_size is not None).

But both of OrderedDict and lru_cache improvements can't be in 3.6 since 3.6 is beta now. I'll try it after 3.6rc1.

-- INADA Naoki <songofacandy at gmail.com>

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