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Merged
youknowone merged 3 commits into from
Jan 14, 2026
Merged

thread.setname and context #6726

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6ff5979
iterable context
youknowone Jan 14, 2026
890b018
thread setname
youknowone Jan 14, 2026
d22c48b
Update crates/vm/src/stdlib/thread.rs
youknowone Jan 14, 2026
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45 changes: 37 additions & 8 deletions crates/stdlib/src/contextvars.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,12 +24,12 @@ thread_local! {
mod _contextvars {
use crate::vm::{
AsObject, Py, PyObjectRef, PyPayload, PyRef, PyResult, VirtualMachine, atomic_func,
builtins::{PyGenericAlias, PyStrRef, PyType, PyTypeRef},
builtins::{PyGenericAlias, PyList, PyStrRef, PyType, PyTypeRef},
class::StaticType,
common::hash::PyHash,
function::{ArgCallable, FuncArgs, OptionalArg},
protocol::{PyMappingMethods, PySequenceMethods},
types::{AsMapping, AsSequence, Constructor, Hashable, Representable},
types::{AsMapping, AsSequence, Constructor, Hashable, Iterable, Representable},
};
use core::{
cell::{Cell, RefCell, UnsafeCell},
Expand Down Expand Up @@ -163,7 +163,7 @@ mod _contextvars {
}
}

#[pyclass(with(Constructor, AsMapping, AsSequence))]
#[pyclass(with(Constructor, AsMapping, AsSequence, Iterable))]
impl PyContext {
#[pymethod]
fn run(
Expand Down Expand Up @@ -205,11 +205,6 @@ mod _contextvars {
self.borrow_vars().len()
}

#[pymethod]
fn __iter__(&self) -> PyResult {
unimplemented!("Context.__iter__ is currently under construction")
}

#[pymethod]
fn get(
&self,
Expand Down Expand Up @@ -238,6 +233,15 @@ mod _contextvars {
let vars = zelf.borrow_vars();
vars.values().map(|value| value.to_owned()).collect()
}

// TODO: wrong return type
#[pymethod]
fn items(zelf: PyRef<Self>, vm: &VirtualMachine) -> Vec<PyObjectRef> {
let vars = zelf.borrow_vars();
vars.iter()
.map(|(k, v)| vm.ctx.new_tuple(vec![k.clone().into(), v.clone()]).into())
.collect()
}
}

impl Constructor for PyContext {
Expand Down Expand Up @@ -281,6 +285,15 @@ mod _contextvars {
}
}

impl Iterable for PyContext {
fn iter(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult {
let vars = zelf.borrow_vars();
let keys: Vec<PyObjectRef> = vars.keys().map(|k| k.clone().into()).collect();
let list = vm.ctx.new_list(keys);
<PyList as Iterable>::iter(list, vm)
}
}

#[pyattr]
#[pyclass(name, traverse)]
#[derive(PyPayload)]
Expand Down Expand Up @@ -574,6 +587,22 @@ mod _contextvars {
) -> PyGenericAlias {
PyGenericAlias::from_args(cls, args, vm)
}

#[pymethod]
fn __enter__(zelf: PyRef<Self>) -> PyRef<Self> {
zelf
}

#[pymethod]
fn __exit__(
zelf: &Py<Self>,
_ty: PyObjectRef,
_val: PyObjectRef,
_tb: PyObjectRef,
vm: &VirtualMachine,
) -> PyResult<()> {
ContextVar::reset(&zelf.var, zelf.to_owned(), vm)
}
}

impl Constructor for ContextToken {
Expand Down
48 changes: 47 additions & 1 deletion crates/vm/src/stdlib/thread.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ pub(crate) use _thread::{
pub(crate) mod _thread {
use crate::{
AsObject, Py, PyPayload, PyRef, PyResult, VirtualMachine,
builtins::{PyDictRef, PyStr, PyTupleRef, PyType, PyTypeRef},
builtins::{PyDictRef, PyStr, PyStrRef, PyTupleRef, PyType, PyTypeRef},
frame::FrameRef,
function::{ArgCallable, Either, FuncArgs, KwArgs, OptionalArg, PySetterValue},
types::{Constructor, GetAttr, Representable, SetAttr},
Expand Down Expand Up @@ -260,6 +260,11 @@ pub(crate) mod _thread {
Ok(())
}

#[pymethod]
fn locked(&self) -> bool {
self.mu.is_locked()
}

#[pymethod]
fn _is_owned(&self) -> bool {
self.mu.is_owned_by_current_thread()
Expand Down Expand Up @@ -293,6 +298,47 @@ pub(crate) mod _thread {
current_thread_id()
}

/// Set the name of the current thread
#[pyfunction]
fn set_name(name: PyStrRef) {
#[cfg(target_os = "linux")]
{
use std::ffi::CString;
if let Ok(c_name) = CString::new(name.as_str()) {
// pthread_setname_np on Linux has a 16-byte limit including null terminator
// TODO: Potential UTF-8 boundary issue when truncating thread name on Linux.
// https://github.com/RustPython/RustPython/pull/6726/changes#r2689379171
let truncated = if c_name.as_bytes().len() > 15 {
CString::new(&c_name.as_bytes()[..15]).unwrap_or(c_name)
} else {
c_name
};
unsafe {
libc::pthread_setname_np(libc::pthread_self(), truncated.as_ptr());
}
}
Comment on lines 304 to 319
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@coderabbitai coderabbitai bot Jan 14, 2026

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⚠️ Potential issue | 🟡 Minor

Potential UTF-8 boundary issue when truncating thread name on Linux.

The truncation at byte 15 may split a multi-byte UTF-8 character, producing an invalid UTF-8 sequence. While CString::new won't fail (it only checks for interior nulls), passing invalid UTF-8 to the OS could cause unexpected behavior.

Consider truncating at a valid UTF-8 character boundary:

Proposed fix 
         #[cfg(target_os = "linux")]
         {
             use std::ffi::CString;
             if let Ok(c_name) = CString::new(name.as_str()) {
                 // pthread_setname_np on Linux has a 16-byte limit including null terminator
-                let truncated = if c_name.as_bytes().len() > 15 {
-                    CString::new(&c_name.as_bytes()[..15]).unwrap_or(c_name)
+                let truncated = if name.as_str().len() > 15 {
+                    // Find a valid UTF-8 boundary at or before byte 15
+                    let s = name.as_str();
+                    let mut end = 15;
+                    while end > 0 && !s.is_char_boundary(end) {
+                        end -= 1;
+                    }
+                    CString::new(&s[..end]).unwrap_or(c_name)
                 } else {
                     c_name
                 };
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
#[cfg(target_os = "linux")]
{
use std::ffi::CString;
if let Ok(c_name) = CString::new(name.as_str()) {
// pthread_setname_np on Linux has a 16-byte limit including null terminator
let truncated = if c_name.as_bytes().len() > 15 {
CString::new(&c_name.as_bytes()[..15]).unwrap_or(c_name)
} else {
c_name
};
unsafe {
libc::pthread_setname_np(libc::pthread_self(), truncated.as_ptr());
}
}
#[cfg(target_os = "linux")]
{
use std::ffi::CString;
if let Ok(c_name) = CString::new(name.as_str()) {
// pthread_setname_np on Linux has a 16-byte limit including null terminator
let truncated = if name.as_str().len() > 15 {
// Find a valid UTF-8 boundary at or before byte 15
let s = name.as_str();
let mut end = 15;
while end > 0 && !s.is_char_boundary(end) {
end -= 1;
}
CString::new(&s[..end]).unwrap_or(c_name)
} else {
c_name
};
unsafe {
libc::pthread_setname_np(libc::pthread_self(), truncated.as_ptr());
}
}
}

}
#[cfg(target_os = "macos")]
{
use std::ffi::CString;
if let Ok(c_name) = CString::new(name.as_str()) {
unsafe {
libc::pthread_setname_np(c_name.as_ptr());
}
}
}
#[cfg(windows)]
{
// Windows doesn't have a simple pthread_setname_np equivalent
// SetThreadDescription requires Windows 10+
let _ = name;
}
#[cfg(not(any(target_os = "linux", target_os = "macos", windows)))]
{
let _ = name;
}
}

/// Get OS-level thread ID (pthread_self on Unix)
/// This is important for fork compatibility - the ID must remain stable after fork
#[cfg(unix)]
Expand Down
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