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Drop replaced tracing callbacks outside locks #9612

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Merged
youknowone merged 2 commits into from
Nov 6, 2026
Merged

Drop replaced tracing callbacks outside locks #9612

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eeef862
Drop replaced tracing callbacks outside locks
youknowdot Nov 3, 2026
53da77d
Document fallible tracing signatures on non-threaded targets
youknowdot Nov 4, 2026
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92 changes: 76 additions & 16 deletions crates/vm/src/stdlib/sys.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1474,11 +1474,13 @@ pub mod sys {
#[pyfunction]
fn setprofile(function: PyObjectRef, vm: &VirtualMachine) {
#[cfg(feature = "threading")]
if let Some(slot) = crate::vm::thread::current_thread_slot() {
*slot.profile_func.lock() = function.clone();
}
vm.profile_func.replace(function);
let old_slot = crate::vm::thread::current_thread_slot()
.map(|slot| core::mem::replace(&mut *slot.profile_func.lock(), function.clone()));
let old_vm = vm.profile_func.replace(function);
update_use_tracing(vm);
#[cfg(feature = "threading")]
drop(old_slot);
drop(old_vm);
}

#[pyfunction]
Expand All @@ -1501,55 +1503,113 @@ pub mod sys {
#[pyfunction]
fn settrace(function: PyObjectRef, vm: &VirtualMachine) {
#[cfg(feature = "threading")]
if let Some(slot) = crate::vm::thread::current_thread_slot() {
*slot.trace_func.lock() = function.clone();
}
vm.trace_func.replace(function);
let old_slot = crate::vm::thread::current_thread_slot()
.map(|slot| core::mem::replace(&mut *slot.trace_func.lock(), function.clone()));
let old_vm = vm.trace_func.replace(function);
update_use_tracing(vm);
// The rest of the current line already started before tracing was
// enabled; sync prev_line so leftover opcodes on this line do not
// emit a spurious 'line' event.
if let Some(frame) = vm.current_frame() {
frame.iframe().sync_prev_line_from_lasti();
}
#[cfg(feature = "threading")]
drop(old_slot);
drop(old_vm);
}

#[pyfunction]
fn _settraceallthreads(function: PyObjectRef, vm: &VirtualMachine) {
#[cfg_attr(
not(feature = "threading"),
expect(
clippy::unnecessary_wraps,
reason = "threading builds can fail to reserve callback storage"
)
)]
fn _settraceallthreads(function: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
let func = (!vm.is_none(&function)).then(|| function.clone());
*vm.state.global_trace_func.lock() = func;
// Retain replaced callbacks until every registry and slot lock has
// been released: their finalizers can reenter these APIs.
let old_global;
#[cfg(feature = "threading")]
let mut old_slots = Vec::new();
#[cfg(feature = "threading")]
{
let registry = vm.state.thread_frames.lock();
if old_slots.try_reserve(registry.len()).is_err() {
drop(registry);
return Err(vm.no_memory_error());
}
old_global = core::mem::replace(&mut *vm.state.global_trace_func.lock(), func);
#[expect(
clippy::iter_over_hash_type,
reason = "every thread slot, order is irrelevant"
)]
for slot in registry.values() {
*slot.trace_func.lock() = function.clone();
old_slots.push(core::mem::replace(
&mut *slot.trace_func.lock(),
function.clone(),
));
}
}
vm.trace_func.replace(function);
#[cfg(not(feature = "threading"))]
{
old_global = core::mem::replace(&mut *vm.state.global_trace_func.lock(), func);
}
let old_vm = vm.trace_func.replace(function);
update_use_tracing(vm);
drop(old_global);
#[cfg(feature = "threading")]
drop(old_slots);
drop(old_vm);
Ok(())
}

#[pyfunction]
fn _setprofileallthreads(function: PyObjectRef, vm: &VirtualMachine) {
#[cfg_attr(
not(feature = "threading"),
expect(
clippy::unnecessary_wraps,
reason = "threading builds can fail to reserve callback storage"
)
)]
fn _setprofileallthreads(function: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
let func = (!vm.is_none(&function)).then(|| function.clone());
*vm.state.global_profile_func.lock() = func;
// Retain replaced callbacks until every registry and slot lock has
// been released: their finalizers can reenter these APIs.
let old_global;
#[cfg(feature = "threading")]
let mut old_slots = Vec::new();
#[cfg(feature = "threading")]
{
let registry = vm.state.thread_frames.lock();
if old_slots.try_reserve(registry.len()).is_err() {
drop(registry);
return Err(vm.no_memory_error());
}
old_global = core::mem::replace(&mut *vm.state.global_profile_func.lock(), func);
#[expect(
clippy::iter_over_hash_type,
reason = "every thread slot, order is irrelevant"
)]
for slot in registry.values() {
*slot.profile_func.lock() = function.clone();
old_slots.push(core::mem::replace(
&mut *slot.profile_func.lock(),
function.clone(),
));
}
}
vm.profile_func.replace(function);
#[cfg(not(feature = "threading"))]
{
old_global = core::mem::replace(&mut *vm.state.global_profile_func.lock(), func);
}
let old_vm = vm.profile_func.replace(function);
update_use_tracing(vm);
drop(old_global);
#[cfg(feature = "threading")]
drop(old_slots);
drop(old_vm);
Ok(())
}

#[cfg(feature = "threading")]
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