Summary

Stop sharing tree-sitter Parser instances between callers.

Review Request #15230 — Created Aug. 14, 2026 and updated Aug. 16, 2026, 2:40 a.m.

Information

Owner

david

Repository

Review Board

Branch

release-9.x

Bugs

Depends On

Reviewers

Groups

reviewboard

People

Description

get_parser() was decorated with @lru_cache, so every caller (and
every thread under threaded WSGI) shared one stateful
tree_sitter.Parser per language. Parsers are not thread-safe, and
_highlight_injections() mutates included_ranges on the shared
instance. A concurrent full-file parse could silently produce a tree
covering only another request's injection ranges, and the corrupt
highlighting would then be stored in the diff chunk cache.

Language objects are immutable and remain cached via get_language().
Parser construction is cheap, so get_parser() now returns a fresh
instance per call.

Testing Done

Added unit tests verifying parsers are not shared and that
included_ranges mutations do not leak into later parsers. Ran all
reviewboard/treesitter tests.

Commits

Summary	ID
Stop sharing tree-sitter Parser instances between callers. `get_parser()` was decorated with `@lru_cache`, so every caller (and every thread under threaded WSGI) shared one stateful `tree_sitter.Parser` per language. Parsers are not thread-safe, and `_highlight_injections()` mutates `included_ranges` on the shared instance. A concurrent full-file parse could silently produce a tree covering only another request's injection ranges, and the corrupt highlighting would then be stored in the diff chunk cache. Language objects are immutable and remain cached via `get_language()`. Parser construction is cheap, so `get_parser()` now returns a fresh instance per call. Testing: Added unit tests verifying parsers are not shared and that included_ranges mutations do not leak into later parsers. Ran all reviewboard/treesitter tests.	ozkosqpyoovrwwknopoxwlmqstwumtsl

Summary

Stop sharing tree-sitter Parser instances between callers.

`get_parser()` was decorated with `@lru_cache`, so every caller (and every thread under threaded WSGI) shared one stateful `tree_sitter.Parser` per language. Parsers are not thread-safe, and `_highlight_injections()` mutates `included_ranges` on the shared instance. A concurrent full-file parse could silently produce a tree covering only another request's injection ranges, and the corrupt highlighting would then be stored in the diff chunk cache. Language objects are immutable and remain cached via `get_language()`. Parser construction is cheap, so `get_parser()` now returns a fresh instance per call. Testing: Added unit tests verifying parsers are not shared and that included_ranges mutations do not leak into later parsers. Ran all reviewboard/treesitter tests.

ozkosqpyoovrwwknopoxwlmqstwumtsl

Issues

Description	From	Last Updated
While here, this should be "Return a ..." to better describe what this does. The method isn't getting an instance …	chipx86	Aug. 16, 2026, 2:40 a.m.
I'd love to keep unit tests standardized across the codebase, but I know you already have a bunch that don't …	chipx86	Aug. 16, 2026, 2:40 a.m.

flake8 passed.

JSHint passed.

Fix it!

reviewboard/treesitter/core.py (Diff revision 1)

An issue was opened. Show all issues

While here, this should be "Return a ..." to better describe what this does. The method isn't getting an instance from somewhere, it's creating and returning one.

reviewboard/treesitter/tests/test_core.py (Diff revision 1)

An issue was opened. Show all issues

I'd love to keep unit tests standardized across the codebase, but I know you already have a bunch that don't use TestCase. But I'd still like to keep the docstring format the same so it's clear for us, for third-parties, and for AIs how unit tests are done across the codebase.