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gh-137562: Remove obsolete comment about calculating incremental threshold#137564

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sergey-miryanov:137562-fix-comments-scan-rate-divisor
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gh-137562: Remove obsolete comment about calculating incremental threshold#137564
sergey-miryanov wants to merge 2 commits into
python:mainfrom
sergey-miryanov:137562-fix-comments-scan-rate-divisor

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@sergey-miryanov

@sergey-miryanov sergey-miryanov commented Aug 8, 2025 •
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gc.c/SCAN_RATE_DIVISOR has obsolete comment about calculating incremental threshold based on count of survivors. It is obsolete since #117120

cpython/Python/gc.c

Lines 1345 to 1362 in 34d7351

/* Making progress in the incremental collector
* In order to eventually collect all cycles
* the incremental collector must progress through the old
* space faster than objects are added to the old space.
*
* Each young or incremental collection adds a number of
* objects, S (for survivors) to the old space, and
* incremental collectors scan I objects from the old space.
* I > S must be true. We also want I > S * N to be where
* N > 1. Higher values of N mean that the old space is
* scanned more rapidly.
* The default incremental threshold of 10 translates to
* N == 1.4 (1 + 4/threshold)
*/
/* Divide by 10, so that the default incremental threshold of 10
* scans objects at 1% of the heap size */
#define SCAN_RATE_DIVISOR 10

@bedevere-app bedevere-app Bot mentioned this pull request Aug 8, 2025
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@sergey-miryanov

sergey-miryanov commented Aug 8, 2025

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I believe this should skip news.

@sergey-miryanov

sergey-miryanov commented Aug 8, 2025

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@markshannon @nascheme Please take a look.

@Eclips4 Eclips4 requested review from markshannon and nascheme August 9, 2025 12:59
@bedevere-app bedevere-app Bot added and removed awaiting review labels Oct 23, 2025
@sergey-miryanov

sergey-miryanov commented Nov 20, 2025

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@markshannon Could you also take a look at this one?

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github-actions Bot commented Apr 27, 2026

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This PR is stale because it has been open for 30 days with no activity.

@github-actions github-actions Bot added the stale Stale PR or inactive for long period of time. label Apr 27, 2026
@sergey-miryanov

sergey-miryanov commented May 3, 2026

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Now that the generational GC has landed, I'll close this as obsolete.

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@efimov-mikhail efimov-mikhail efimov-mikhail approved these changes

@nascheme nascheme Awaiting requested review from nascheme

@markshannon markshannon Awaiting requested review from markshannon

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@sergey-miryanov @efimov-mikhail @Eclips4 @nazeerali4325-commits