Cinder: Instagram's performance-oriented fork of CPython

Re:Cinder: Instagram's performance-oriented fork of CPython by karlding on Wednesday May 05, 2021 @02:38AM (#27046867)

Looking through the repo, one change of note that doesn't seem to be documented in the README [0] is that this has an optimization to reduce Copy on Writes in forked workers (under the Py_IMMORTAL_INSTANCES preprocessor guard) by not dirtying pages via refcount changes.

Here's the BPO issue [1] that tracks the upstreaming attempt.

[0] https://github.com/facebookincubator/cinder/blob/9de726349eb...

[1] https://bugs.python.org/issue40255

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Re:Cinder: Instagram's performance-oriented fork of CPython by _carljm on Wednesday May 05, 2021 @08:28AM (#27049023)

It’s also likely that this change, which is a big win for our prefork production environment, drags down our benchmark results. It makes every incref and decref more expensive.

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Re:Cinder: Instagram's performance-oriented fork of CPython by kingmaker on Wednesday May 05, 2021 @03:27AM (#27047138)

Good call out! I’ll make sure it ends up in the readme.

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