Drop cached values in type_cache_clear_version to prevent refcount leaks

youknowone · youknowone · commit 3ccbe5187196 · 2026-03-03T20:55:06.000+09:00
Restore value dropping when invalidating cache entries for a specific
version tag. Without this, cached PyObjectRef values were leaked until
entry reuse, causing inflated sys.getrefcount() in test_memoryview.
diff --git a/crates/vm/src/builtins/type.rs b/crates/vm/src/builtins/type.rs
@@ -132,16 +132,19 @@ fn type_cache_hash(version: u32, name: &'static PyStrInterned) -> usize {
     ((version ^ name_hash) as usize) & TYPE_CACHE_MASK
 }
 
-/// Invalidate cache entries for a specific version tag.
-/// Called from modified() when a type is changed. Only sets version to 0;
-/// value pointers are left in place and cleaned up when entries are reused
-/// (populate) or during type_cache_clear (GC).
+/// Invalidate cache entries for a specific version tag and release values.
+/// Called from modified() when a type is changed.
 fn type_cache_clear_version(version: u32) {
+    let mut to_drop = Vec::new();
     for entry in TYPE_CACHE.iter() {
         if entry.version.load(Ordering::Relaxed) == version {
             entry.version.store(0, Ordering::Release);
+            if let Some(v) = entry.take_value() {
+                to_drop.push(v);
+            }
         }
     }
+    drop(to_drop);
 }
 
 /// Clear all type cache entries.

Original file line number	Diff line number	Diff line change
`@@ -132,16 +132,19 @@ fn type_cache_hash(version: u32, name: &'static PyStrInterned) -> usize {`
`132`	`132`	`((version ^ name_hash) as usize) & TYPE_CACHE_MASK`
`133`	`133`	`}`
`134`	`134`
`135`		`-/// Invalidate cache entries for a specific version tag.`
`136`		`-/// Called from modified() when a type is changed. Only sets version to 0;`
`137`		`-/// value pointers are left in place and cleaned up when entries are reused`
`138`		`-/// (populate) or during type_cache_clear (GC).`
	`135`	`+/// Invalidate cache entries for a specific version tag and release values.`
	`136`	`+/// Called from modified() when a type is changed.`
`139`	`137`	`fn type_cache_clear_version(version: u32) {`
	`138`	`+ let mut to_drop = Vec::new();`
`140`	`139`	`for entry in TYPE_CACHE.iter() {`
`141`	`140`	`if entry.version.load(Ordering::Relaxed) == version {`
`142`	`141`	`entry.version.store(0, Ordering::Release);`
	`142`	`+ if let Some(v) = entry.take_value() {`
	`143`	`+ to_drop.push(v);`
	`144`	`+ }`
`143`	`145`	`}`
`144`	`146`	`}`
	`147`	`+ drop(to_drop);`
`145`	`148`	`}`
`146`	`149`
`147`	`150`	`/// Clear all type cache entries.`