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bpo-40521: Remove freelist from collections.deque() #21073

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Merged
merged 1 commit into from
Jun 23, 2020
Merged

bpo-40521: Remove freelist from collections.deque() #21073

merged 1 commit into from
Jun 23, 2020

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rhettinger
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@rhettinger rhettinger commented Jun 23, 2020 •
edited by bedevere-bot
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vstinner
vstinner approved these changes Jun 23, 2020
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LGTM.

But I'm curious, why removing it? The free list is not longer faster than always calling PyMem_Malloc/PyMem_Free?

Previously, PyMem_Malloc/PyMem_Free called libc malloc/free. But now it's the pymalloc memory allocator which is faster than libc allocator for small memory allocation (up to 512 bytes). Maybe pymalloc made the free list less interesting?

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Deques only call the allocator once every 64 updates, so the average cost is small.

@rhettinger rhettinger merged commit 32f2eda into python:master Jun 23, 2020
fasih pushed a commit to fasih/cpython that referenced this pull request Jun 29, 2020
@rhettinger @fasihahmad
bpo-40521: Remove freelist from collections.deque() (pythonGH-21073)
2a1fe84
arun-mani-j pushed a commit to arun-mani-j/cpython that referenced this pull request Jul 21, 2020
@rhettinger @arun-mani-j
bpo-40521: Remove freelist from collections.deque() (pythonGH-21073)
3183252
rhettinger added a commit to rhettinger/cpython that referenced this pull request Mar 20, 2021
@rhettinger
Revert "bpo-40521: Remove freelist from collections.deque() (pythonGH…
39ebce3 
…-21073)"

This reverts commit 32f2eda.
It can be re-applied if the subinterpreter PEP is approved.
Otherwise, the commit degraded performance with no offsetting
benefit.
rhettinger added a commit that referenced this pull request Mar 25, 2021
@rhettinger
Revert "bpo-40521: Remove freelist from collections.deque() (GH-21073)…
3bb1987 
…" (GH-24944)

This reverts commit 32f2eda.
It can be re-applied if the subinterpreter PEP is approved.
Otherwise, the commit degraded performance with no offsetting
benefit.
@vstinner vstinner mentioned this pull request Apr 10, 2022
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