gemini-code-assist[bot] commented on code in PR #327:
URL: https://github.com/apache/tvm-ffi/pull/327#discussion_r2610816937
##########
python/tvm_ffi/error.py:
##########
@@ -121,19 +121,29 @@ def append_traceback(
The new traceback with the appended frame.
"""
- frame = self._create_frame(filename, lineno, func)
- return types.TracebackType(tb, frame, frame.f_lasti, lineno)
+
+ # Magic hack to prevent a circular reference
Review Comment:
While "Magic hack" is evocative, a more descriptive comment would improve
long-term maintainability by explaining the mechanism. This pattern prevents a
reference cycle between the newly created frame object and the current
function's frame.
```python
# Using a nested function to construct the traceback object avoids a
# reference cycle between the new frame and this function's frame.
```
##########
python/tvm_ffi/error.py:
##########
@@ -121,19 +121,29 @@ def append_traceback(
The new traceback with the appended frame.
"""
- frame = self._create_frame(filename, lineno, func)
- return types.TracebackType(tb, frame, frame.f_lasti, lineno)
+
+ # Magic hack to prevent a circular reference
+ def create(
+ tb: types.TracebackType | None, frame: types.FrameType, lineno: int
+ ) -> types.TracebackType:
+ return types.TracebackType(tb, frame, frame.f_lasti, lineno)
+
+ return create(tb, self._create_frame(filename, lineno, func), lineno)
_TRACEBACK_MANAGER = TracebackManager()
def _with_append_backtrace(py_error: BaseException, backtrace: str) ->
BaseException:
"""Append the backtrace to the py_error and return it."""
- tb = py_error.__traceback__
- for filename, lineno, func in _parse_backtrace(backtrace):
- tb = _TRACEBACK_MANAGER.append_traceback(tb, filename, lineno, func)
- return py_error.with_traceback(tb)
+ # we manually delete py_error and tb to avoid reference cycle, making it
faster to gc the locals inside the frame
+ try:
+ tb = py_error.__traceback__
+ for filename, lineno, func in _parse_backtrace(backtrace):
+ tb = _TRACEBACK_MANAGER.append_traceback(tb, filename, lineno,
func)
+ return py_error.with_traceback(tb)
+ finally:
+ del py_error, tb
Review Comment:
This `del` statement could raise a `NameError` if an exception occurs within
the `try` block before `tb` is assigned (e.g., if `py_error.__traceback__`
raises an exception on line 141). This `NameError` would then mask the
original, more informative exception. To make this more robust, it's safer to
delete `py_error` and `tb` separately and wrap the deletion of `tb` in a
`try...except NameError` block to handle cases where it's not defined.
```python
del py_error
try:
del tb
except NameError:
pass
```
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