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Handle EINTR retry in os.write() (PEP 475) #7482

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Merged
youknowone merged 2 commits into from
Mar 25, 2026
Merged

Handle EINTR retry in os.write() (PEP 475) #7482

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5b77f1d
Handle EINTR retry in os.write() (PEP 475)
youknowone Mar 23, 2026
b2aef25
Add atomic snapshot for dict/dict_keys in extract_elements
youknowone Mar 23, 2026
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1 change: 0 additions & 1 deletion Lib/test/_test_eintr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -163,7 +163,6 @@ def test_readinto(self):
self.assertEqual(os.readinto(fd, buffer), len(expected))
self.assertEqual(buffer, expected)

@unittest.expectedFailure # TODO: RUSTPYTHON; InterruptedError: [Errno 4] Interrupted system call
def test_write(self):
rd, wr = os.pipe()
self.addCleanup(os.close, wr)
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2 changes: 0 additions & 2 deletions Lib/test/_test_multiprocessing.py
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Expand Up @@ -4814,8 +4814,6 @@ def test_finalize(self):
self.assertEqual(result, ['a', 'b', 'd10', 'd03', 'd02', 'd01', 'e'])

@support.requires_resource('cpu')
# TODO: RUSTPYTHON; dict iteration races with concurrent GC mutations
@unittest.expectedFailure
def test_thread_safety(self):
# bpo-24484: _run_finalizers() should be thread-safe
def cb():
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19 changes: 13 additions & 6 deletions crates/vm/src/stdlib/os.rs
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Expand Up @@ -321,12 +321,19 @@ pub(super) mod _os {
}

#[pyfunction]
fn write(
fd: crt_fd::Borrowed<'_>,
data: ArgBytesLike,
vm: &VirtualMachine,
) -> io::Result<usize> {
data.with_ref(|b| vm.allow_threads(|| crt_fd::write(fd, b)))
fn write(fd: crt_fd::Borrowed<'_>, data: ArgBytesLike, vm: &VirtualMachine) -> PyResult<usize> {
data.with_ref(|b| {
loop {
match vm.allow_threads(|| crt_fd::write(fd, b)) {
Ok(n) => return Ok(n),
Err(e) if e.raw_os_error() == Some(libc::EINTR) => {
vm.check_signals()?;
continue;
}
Err(e) => return Err(e.into_pyexception(vm)),
}
}
})
}

#[cfg(not(windows))]
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14 changes: 10 additions & 4 deletions crates/vm/src/vm/mod.rs
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Expand Up @@ -22,7 +22,7 @@ use crate::{
self, PyBaseExceptionRef, PyDict, PyDictRef, PyInt, PyList, PyModule, PyStr, PyStrInterned,
PyStrRef, PyTypeRef, PyUtf8Str, PyUtf8StrInterned, PyWeak,
code::PyCode,
dict::{PyDictItems, PyDictValues},
dict::{PyDictItems, PyDictKeys, PyDictValues},
pystr::AsPyStr,
tuple::PyTuple,
},
Expand Down Expand Up @@ -1822,24 +1822,30 @@ impl VirtualMachine {
where
F: Fn(PyObjectRef) -> PyResult<T>,
{
// Extract elements from item, if possible:
// Type-specific fast paths corresponding to _list_extend() in CPython
// Objects/listobject.c. Each branch takes an atomic snapshot to avoid
// race conditions from concurrent mutation (no GIL).
let cls = value.class();
let list_borrow;
let slice = if cls.is(self.ctx.types.tuple_type) {
value.downcast_ref::<PyTuple>().unwrap().as_slice()
} else if cls.is(self.ctx.types.list_type) {
list_borrow = value.downcast_ref::<PyList>().unwrap().borrow_vec();
&list_borrow
} else if cls.is(self.ctx.types.dict_type) {
let keys = value.downcast_ref::<PyDict>().unwrap().keys_vec();
return keys.into_iter().map(func).collect();
} else if cls.is(self.ctx.types.dict_keys_type) {
let keys = value.downcast_ref::<PyDictKeys>().unwrap().dict.keys_vec();
return keys.into_iter().map(func).collect();
} else if cls.is(self.ctx.types.dict_values_type) {
// Atomic snapshot of dict values - prevents race condition during iteration
let values = value
.downcast_ref::<PyDictValues>()
.unwrap()
.dict
.values_vec();
return values.into_iter().map(func).collect();
} else if cls.is(self.ctx.types.dict_items_type) {
// Atomic snapshot of dict items - prevents race condition during iteration
let items = value
.downcast_ref::<PyDictItems>()
.unwrap()
Expand Down
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