Not expecting multiple simultaneous reads for a given frame

vm/src/frame.rs

@@ -1,6 +1,6 @@
 use std::fmt;
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::{Mutex, RwLock};
+use std::sync::Mutex;
 
 use indexmap::IndexMap;
 use itertools::Itertools;
@@ -93,7 +93,7 @@ pub struct Frame {
     /// index of last instruction ran
     pub lasti: AtomicUsize,
     /// marker to know if this frame is being traced
-    pub trace: RwLock<PyObjectRef>,
+    pub trace: Mutex<PyObjectRef>,
     state: Mutex<FrameState>,
 }
 
@@ -169,7 +169,7 @@ impl Frame {
                 stack: Vec::new(),
                 blocks: Vec::new(),
             }),
-            trace: RwLock::new(vm.get_none()),
+            trace: Mutex::new(vm.get_none()),
         }
     }
 }

vm/src/obj/objframe.rs

@@ -71,13 +71,13 @@ impl FrameRef {
 
     #[pyproperty]
     fn f_trace(self) -> PyObjectRef {
-        let boxed = self.trace.read();
+        let boxed = self.trace.lock();
         boxed.unwrap().clone()
     }
 
     #[pyproperty(setter)]
     fn set_f_trace(self, value: PyObjectRef) {
-        let mut storage = self.trace.write().unwrap();
+        let mut storage = self.trace.lock().unwrap();
         *storage = value;
     }
 }