thread_inherit_context, upgrade threading & contextvar by youknowone · Pull Request #6727 · RustPython/RustPython

youknowone · 2026-01-14T08:21:57Z

~~TODO: update tests~~

Summary by CodeRabbit

New Features
- Added a new configuration flag to control whether new threads inherit parent context. Defaults to disabled.
- Exposed the option via command-line X-option and an environment variable, with validation and consistent error messaging.

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coderabbitai · 2026-01-14T08:22:04Z

📝 Walkthrough

Walkthrough

Adds a new boolean setting thread_inherit_context to runtime configuration, propagates it from Settings into FlagsData, and wires parsing/validation for the X-option and environment variable (PYTHON_THREAD_INHERIT_CONTEXT) to control the flag.

Changes

Cohort / File(s)	Summary
Settings structure expansion `crates/vm/src/vm/setting.rs`	Added public boolean field `thread_inherit_context` with doc comment and set default to `false` in `Default` implementation.
FlagsData structure expansion `crates/vm/src/stdlib/sys.rs`	Added boolean field `thread_inherit_context` to `FlagsData` and wired `from_settings` to initialize it from `settings.thread_inherit_context`.
X-option / env parsing `src/settings.rs`	Added parsing and validation for `thread_inherit_context` in X-options and `PYTHON_THREAD_INHERIT_CONTEXT` env var; accepts `1`/`0`, errors on invalid values and sets `settings.thread_inherit_context` accordingly.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A tiny flag hops into place,
From env and X it finds its space,
Parent context may or may not be shared,
Two structs now carry what was declared,
A rabbit nods—configuration prepared. ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'thread_inherit_context, upgrade threading & contextvar' directly reflects the main changes: it adds thread_inherit_context configuration and upgrades threading and contextvar modules.

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✨ Finishing touches

📝 Generate docstrings

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coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@crates/vm/src/vm/setting.rs`:
- Around line 91-92: The CLI parser never wires the
Settings.thread_inherit_context flag into the -X option match, so -X
thread_inherit_context has no effect; update the match in the -X parsing logic
(the code handling dev, faulthandler, warn_default_encoding, etc.) to handle the
"thread_inherit_context" token and set sys.flags.thread_inherit_context (or
Settings.thread_inherit_context) to true when seen (and handle disabling if
parser supports "no_thread_inherit_context" or "thread_inherit_context=0");
ensure you reference the same flag name (thread_inherit_context) and the
Settings/sys.flags field so the value flows from CLI into Settings.

🧹 Nitpick comments (1)

crates/vm/src/stdlib/sys.rs (1)

1329-1329: Consider adding sys.flags coverage for the new flag.

Given the PR note about pending tests, please add/extend tests to assert sys.flags.thread_inherit_context for both default and enabled configurations.

If you want, I can draft the test updates.

crates/vm/src/vm/setting.rs

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/settings.rs`:
- Around line 314-327: The PYTHON_THREAD_INHERIT_CONTEXT env handling currently
runs after the -X thread_inherit_context option and thus overrides the X-option;
move the shown get_env("PYTHON_THREAD_INHERIT_CONTEXT") block so it executes
before the code that parses/handles the -X thread_inherit_context option (the
block that sets settings.thread_inherit_context from the -X flag), ensuring the
command-line -X thread_inherit_context takes precedence (consistent with
int_max_str_digits behavior).

coderabbitai · 2026-01-17T15:43:14Z

src/settings.rs

+    if let Some(val) = get_env("PYTHON_THREAD_INHERIT_CONTEXT") {
+        settings.thread_inherit_context = match val.to_str() {
+            Some("1") => true,
+            Some("0") => false,
+            _ => {
+                error!(
+                    "Fatal Python error: config_init_thread_inherit_context: \
+                     PYTHON_THREAD_INHERIT_CONTEXT=N: N is missing or invalid\n\
+                     Python runtime state: preinitialized"
+                );
+                std::process::exit(1);
+            }
+        };
+    }


⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash # Check PYTHONINTMAXSTRDIGITS and int_max_str_digits handling to compare precedence # Look for PYTHONINTMAXSTRDIGITS handling rg -n -B5 -A10 "PYTHONINTMAXSTRDIGITS" src/settings.rs # Check int_max_str_digits processing order echo "---" rg -n "int_max_str_digits" src/settings.rs

Repository: RustPython/RustPython

Length of output: 1647

🏁 Script executed:

#!/bin/bash # Get detailed view of lines 288-327 to see the exact order of processing sed -n '280,330p' src/settings.rs | cat -n

Repository: RustPython/RustPython

Length of output: 2419

Fix precedence: X-option should override environment variable, not vice versa.

The environment variable PYTHON_THREAD_INHERIT_CONTEXT (lines 315-328) is processed after the -X thread_inherit_context option (lines 289-301), causing it to override the X-option. This is inconsistent with the handling of int_max_str_digits, where the X-option is processed last and takes precedence. Reorder to process the environment variable before the X-option block to ensure command-line options take precedence, or document this as intentional behavior if it differs from Python's design.

🤖 Prompt for AI Agents

In `@src/settings.rs` around lines 314 - 327, The PYTHON_THREAD_INHERIT_CONTEXT env handling currently runs after the -X thread_inherit_context option and thus overrides the X-option; move the shown get_env("PYTHON_THREAD_INHERIT_CONTEXT") block so it executes before the code that parses/handles the -X thread_inherit_context option (the block that sets settings.thread_inherit_context from the -X flag), ensuring the command-line -X thread_inherit_context takes precedence (consistent with int_max_str_digits behavior).

youknowone changed the title ~~thread_inherit_context, upgrade threading & contextvar (3.14)~~ thread_inherit_context, upgrade threading & contextvar Jan 17, 2026

youknowone force-pushed the thread_inherit_context branch from 63912db to b85ba35 Compare January 17, 2026 14:28

youknowone marked this pull request as ready for review January 17, 2026 14:28

coderabbitai bot reviewed Jan 17, 2026

View reviewed changes

crates/vm/src/vm/setting.rs Show resolved Hide resolved

youknowone and others added 3 commits January 18, 2026 00:39

thread_inherit_context

5508c44

Update contextvar, threading from CPython 3.14.2

53eedab

partially patch test_sys to 3.14.2

a674563

youknowone force-pushed the thread_inherit_context branch from b85ba35 to a674563 Compare January 17, 2026 15:40

coderabbitai bot reviewed Jan 17, 2026

View reviewed changes

youknowone merged commit ca76cb7 into RustPython:main Jan 17, 2026
23 of 24 checks passed

youknowone deleted the thread_inherit_context branch January 17, 2026 23:53

coderabbitai bot mentioned this pull request Jan 18, 2026

Update Lib/warnings to CPython 3.14 #6762

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thread_inherit_context, upgrade threading & contextvar #6727

thread_inherit_context, upgrade threading & contextvar #6727
youknowone merged 3 commits intoRustPython:mainfrom
youknowone:thread_inherit_context

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youknowone commented Jan 14, 2026 •

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