chore: release json2xml 6.3.0

[vinitkumar]

json2xml 6.3.0 and json2xml_rs 0.4.0

Released 2026-06-10.

Highlights

• Reduced allocation pressure in the pure Python serializer hot paths for dicts, lists, scalar values, XML names, and emitted attributes.
• Kept the Python and Rust release line aligned: json2xml[fast] now requires json2xml-rs>=0.4.0.
• Documented the Rust memory benchmark in enough detail to reproduce the 100,000-record RSS measurement and understand the throughput tradeoff.

Why Upgrade

This release is focused on large conversion workloads. The 6.2.0 Rust release moved accelerator output directly into Python bytes to reduce peak serializer memory; 6.3.0 follows that with Python-side allocation reductions so fallback and unsupported-option paths also benefit.

No XML shape changes are intended. Existing callers should see the same output for supported options, including invalid-name normalization, @attrs/@val handling, list wrapping, XPath mode, and pure Python fallback behavior.

Package Versions

• Python package: json2xml==6.3.0
• Rust accelerator package: json2xml-rs==0.4.0
• Fast install: pip install "json2xml[fast]"

Changelog

• feat: reduce pure Python serializer allocations in hot dict, list, and scalar paths.
• feat: preserve XML output semantics while reusing validated element-name and attribute work.
• perf: lower peak memory pressure for large conversions after the 6.2.0 Rust bytes-writer release.
• docs: add hyperfine Rust memory benchmark notes with reproduction details and the measured throughput tradeoff.
• chore: release json2xml-rs 0.4.0 and require it from json2xml[fast] for accelerated installs.

Verification

The release changes are covered by the existing serializer, fast-backend, and Rust parity tests. The benchmark documentation records the measurement setup separately from the functional test suite so release consumers can reproduce performance results on their own hardware.

Summary by Sourcery

Release json2xml 6.3.0 and json2xml_rs 0.4.0 with aligned Python and Rust packages and updated performance documentation.

New Features:

• Reduce allocations in pure Python serializer hot paths while preserving existing XML output semantics.

Enhancements:

• Align the Python fast extra requirement with the new json2xml_rs 0.4.0 accelerator release.
• Clarify architecture and packaging documentation around version alignment and release notes location.
• Update Rust performance notes to describe the 0.4.0 allocator and RSS improvements over 0.3.0.

Build:

• Bump Python package version to 6.3.0 and Rust accelerator versions to 0.4.0 in project metadata.

Documentation:

• Add RELEASE_NOTES.md summarizing the 6.3.0 / 0.4.0 release, rationale, and benchmark details.

[sourcery-ai]

Reviewer's Guide

Release json2xml 6.3.0 and json2xml_rs 0.4.0, aligning Python and Rust package versions/requirements and updating release and benchmark documentation to reflect the new Rust accelerator behavior and memory characteristics.

File-Level Changes

Change	Details	Files
Bump Python and Rust package versions and align the fast extra requirement with the new accelerator release.	Update the core Python package version from 6.2.0 to 6.3.0 in project metadata and package init Update the Rust accelerator crate and wheel metadata from 0.3.0 to 0.4.0 Tighten the json2xml[fast] extra requirement to depend on json2xml-rs>=0.4.0	pyproject.toml json2xml/__init__.py rust/Cargo.toml rust/pyproject.toml
Refresh Rust README and architecture docs to describe the 0.4.0 allocator and release processes, including release-note locations.	Describe json2xml_rs 0.4.0 as building on the direct Python bytes writer with lower allocation pressure and clarify its relationship to the 0.3.0 improvements Clarify that Python and Rust versions are kept aligned via requirements and explicitly document where Python, Rust, and release-note versions live	rust/README.md lat.md/architecture.md
Add standalone release notes for the 6.3.0 / 0.4.0 release, including performance and verification details.	Introduce RELEASE_NOTES.md capturing highlights, upgrade rationale, package versions, changelog bullets, and verification strategy for this release	RELEASE_NOTES.md

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (0355496) to head (ec224ce).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #319   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            6         6           
  Lines          616       616           
=========================================
  Hits           616       616           

Flag	Coverage Δ
unittests	100.00% <ø> (ø)

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