Author vstinner
Recipients eric.snow, jkloth, nanjekyejoannah, ncoghlan, vstinner
Date 2020-02-01.00:30:57
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Message-id <1580517057.49.0.13192433757.issue39511@roundup.psfhosted.org>
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> Would it not suffice to just make the singletons "immortal"?

The problem is to make Py_INCREF/Py_DECREF efficient. Last time someone tried to use an atomic variable for ob_refcnt, it was 20% slower if I recall correctly. If many threads start to update such atomic variable, the CPU cacheline of common singletons like None, True and False can quickly become a performance bottleneck.

On the other side, if each interpreter has its own objects, there is no need to protect ob_refcnt, the interpreter lock protects it.
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2020-02-01 00:30:57vstinnersetrecipients: + vstinner, ncoghlan, jkloth, eric.snow, nanjekyejoannah
2020-02-01 00:30:57vstinnersetmessageid: <1580517057.49.0.13192433757.issue39511@roundup.psfhosted.org>
2020-02-01 00:30:57vstinnerlinkissue39511 messages
2020-02-01 00:30:57vstinnercreate