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

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

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@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 It is obsolete since #117120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

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I believe this should skip news.

@sergey-miryanov
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@markshannon @nascheme Please take a look.

@Eclips4 Eclips4 requested review from nascheme and markshannon August 9, 2025 12:59
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@nascheme nascheme Awaiting requested review from nascheme

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@sergey-miryanov @Eclips4