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Fix thread-safety in GC, type cache, and instruction cache #7355

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Merged
youknowone merged 6 commits into from
Mar 5, 2026
Merged

Fix thread-safety in GC, type cache, and instruction cache #7355

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70169e8
Fix thread-safety in GC, type cache, and instruction cache
youknowone Mar 5, 2026
b0ad917
Fix RLock _acquire_restore tuple handling and unxfail threading test
youknowone Mar 5, 2026
de01099
Align type cache seqlock writer protocol with CPython
youknowone Mar 5, 2026
8683977
RLock: use single parking_lot level, track recursion manually
youknowone Mar 5, 2026
3e31d22
Add try_to_owned_from_ptr to avoid &PyObject on stale ptrs
youknowone Mar 5, 2026
b3de227
Fix CI: spelling typo and xfail flaky test_thread_safety
youknowone Mar 5, 2026
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Align type cache seqlock writer protocol with CPython
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@youknowone
youknowone committed Mar 5, 2026
commit de010994143681b51d739e7dacad70c352ff2490
4 changes: 4 additions & 0 deletions crates/compiler-core/src/bytecode.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -623,6 +623,10 @@ impl CodeUnits {
///
/// # Safety
/// - `index` must be in bounds.
/// - `value` must be `0` or a valid `*const PyObject` encoded as `usize`.
/// - Callers must follow the cache invalidation/upgrade protocol:
/// invalidate the version guard before writing and publish the new
/// version after writing.
pub unsafe fn write_cache_ptr(&self, index: usize, value: usize) {
self.pointer_cache[index].store(value, Ordering::Relaxed);
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}
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23 changes: 22 additions & 1 deletion crates/vm/src/builtins/type.rs
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Expand Up @@ -104,7 +104,28 @@ impl TypeCacheEntry {

#[inline]
fn begin_write(&self) {
self.sequence.fetch_add(1, Ordering::AcqRel);
let mut seq = self.sequence.load(Ordering::Acquire);
loop {
while (seq & 1) != 0 {
core::hint::spin_loop();
seq = self.sequence.load(Ordering::Acquire);
}
match self.sequence.compare_exchange_weak(
seq,
seq.wrapping_add(1),
Ordering::AcqRel,
Ordering::Acquire,
) {
Ok(_) => {
core::sync::atomic::fence(Ordering::Release);
break;
}
Err(observed) => {
core::hint::spin_loop();
seq = observed;
}
}
}
}

#[inline]
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