don't store exceptionfor identity check

Author: maxbachmann

src/debugpy/_vendored/pydevd/_pydevd_sys_monitoring/_pydevd_sys_monitoring.py

@@ -178,11 +178,11 @@ def _get_unhandled_exception_frame(exc, depth: int) -> Optional[FrameType]:
 # fmt: on
     try:
         # Unhandled frame has to be from the same exception.
-        if _thread_local_info.f_unhandled_exc is exc:
+        if _thread_local_info.f_unhandled_exc_id is id(exc):
             return _thread_local_info.f_unhandled_frame
         else:
             del _thread_local_info.f_unhandled_frame
-            del _thread_local_info.f_unhandled_exc
+            del _thread_local_info.f_unhandled_exc_id
             raise AttributeError('Not the same exception')
     except:
         f_unhandled = _getframe(depth)
@@ -222,7 +222,7 @@ def _get_unhandled_exception_frame(exc, depth: int) -> Optional[FrameType]:
 
         if f_unhandled is not None:
             _thread_local_info.f_unhandled_frame = f_unhandled
-            _thread_local_info.f_unhandled_exc = exc
+            _thread_local_info.f_unhandled_exc_id = id(exc)
             return _thread_local_info.f_unhandled_frame
 
         return f_unhandled
@@ -966,6 +966,20 @@ def _raise_event(code, instruction, exc):
     if func_code_info.always_skip_code:
         return
 
+    # A new exception is starting. Invalidate the cache to prevent ABA bugs.
+    try:
+        del _thread_local_info.f_unhandled_frame
+        del _thread_local_info.f_unhandled_exc_id
+    except AttributeError:
+        pass
+
+    has_caught_exception_breakpoint_in_pydb = (
+        py_db.break_on_caught_exceptions or py_db.break_on_user_uncaught_exceptions or py_db.has_plugin_exception_breaks
+    )
+    if has_caught_exception_breakpoint_in_pydb:
+        return
+
+
     frame = _getframe(1)
     arg = (type(exc), exc, exc.__traceback__)
 
@@ -1864,18 +1878,13 @@ def update_monitor_events(suspend_requested: Optional[bool]=None) -> None:
 
     break_on_uncaught_exceptions = py_db.break_on_uncaught_exceptions
 
-    if has_caught_exception_breakpoint_in_pydb:
+    if has_caught_exception_breakpoint_in_pydb or break_on_uncaught_exceptions:
         required_events |= monitor.events.RAISE | monitor.events.PY_UNWIND
-        # print('track RAISE')
         monitor.register_callback(DEBUGGER_ID, monitor.events.RAISE, _raise_event)
         monitor.register_callback(DEBUGGER_ID, monitor.events.PY_UNWIND, _unwind_event)
     else:
-        if break_on_uncaught_exceptions:
-            required_events |= monitor.events.PY_UNWIND
-            monitor.register_callback(DEBUGGER_ID, monitor.events.PY_UNWIND, _unwind_event)
-        else:
-            monitor.register_callback(DEBUGGER_ID, monitor.events.RAISE, None)
-            monitor.register_callback(DEBUGGER_ID, monitor.events.PY_UNWIND, None)
+        monitor.register_callback(DEBUGGER_ID, monitor.events.RAISE, None)
+        monitor.register_callback(DEBUGGER_ID, monitor.events.PY_UNWIND, None)
 
     has_breaks = py_db.has_plugin_line_breaks
     if not has_breaks: