[New-bugs-announce] [issue18797] Don't needlessly change refcounts of dummy objects for sets

[Raymond Hettinger]

New submission from Raymond Hettinger:

AFAICT, there is no reason for sets to incref and decref dummy objects.  The dummy object address is used as placeholders in the hash table but it is never accessed by set the logic.   As long the one reference is held at the time the dummy object is created, nothing further is served by the increfs and decrefs.

I can take them out entirely or use ifdefs to keep them for debug builds.

Does anyone know of any issues?

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components: Interpreter Core
files: no_refcnt_dummy1.diff
keywords: patch
messages: 195751
nosy: rhettinger
priority: normal
severity: normal
status: open
title: Don't needlessly change refcounts of dummy objects for sets
type: performance
versions: Python 3.4
Added file: http://bugs.python.org/file31394/no_refcnt_dummy1.diff

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<http://bugs.python.org/issue18797>
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