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GeezerVison is showing github.com — Performance: Reduce refcount churn in csv.reader · Issue #156748 · python/cpython

Performance: Reduce refcount churn in csv.reader #156748

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Performance: Reduce refcount churn in csv.reader#156748
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extension-modulesC modules in the Modules dirC modules in the Modules dirperformancePerformance or resource usagePerformance or resource usagetype-featureA feature request or enhancementA feature request or enhancement

Description

@brittanyrey
brittanyrey
opened on Aug 31, 2026
Issue body actions

Minor change to reduce churn in parse_save_field(). It currently calls PyList_Append(self->fields, field); Py_DECREF(field) for every field of every row. PyList_Append internally does Py_NewRef(newitem), so each field pays an incref immediately followed by a decref, plus a critical-section enter/exit.
Since the reference is already about to be dropped, just pass the reference directly to the caller.

(PR is written & ready to attach)

Linked PRs

  • gh-156748 : Performance - Use takeref append in _csv #156749

Activity

  1. aisk
    added
    type-featureA feature request or enhancementA feature request or enhancement
    performancePerformance or resource usagePerformance or resource usage
    extension-modulesC modules in the Modules dirC modules in the Modules dir
    on Sep 1, 2026
  2. aisk
    added this to CSV issues 📊on Sep 1, 2026

  3. eendebakpt commented on Sep 1, 2026

    @eendebakpt
    eendebakpt
    on Sep 1, 2026
    Contributor
    More actions

    This one is covered by #150942

  4. picnixz
    closed this as a duplicateof Improve performance by using reference stealing methods #150942 on Sep 1, 2026
  5. github-project-automation
    moved this to Done in CSV issues 📊on Sep 1, 2026
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    extension-modulesC modules in the Modules dirC modules in the Modules dirperformancePerformance or resource usagePerformance or resource usagetype-featureA feature request or enhancementA feature request or enhancement

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