AmosG commented on issue #51861:
URL: https://github.com/apache/airflow/issues/51861#issuecomment-3591637288
I've successfully reproduced and fixed this issue!
I do think this is high priority - writing and debugging code is a critical
task
## Root Cause
The problem occurs because **debuggers try to introspect the context
dictionary** to display variables. In Airflow 3.x, the context contains
`VariableAccessor`, `ConnectionAccessor`, and `MacrosAccessor` objects that use
`__getattr__` for dynamic access.
When the debugger calls `hasattr(obj, "__iter__")` to check if these objects
are iterable, it triggers `__getattr__("__iter__")`, which attempts to fetch a
variable named `"__iter__"` from the Airflow variable store, causing the
infinite loop.
### Stack Trace Evidence
```python
File "debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_safe_repr.py", line
128, in _is_long_iter
if not hasattr(obj, "__iter__"):
File "airflow/sdk/execution_time/context.py", line 390, in __getattr__
return _get_variable(key, self._deserialize_json)
```
## The Solution
Add explicit `__iter__` methods to the Accessor classes in
`airflow/sdk/execution_time/context.py`:
### Changes Required
**1. VariableAccessor** (after `__repr__` method, around line 393):
```python
def __iter__(self):
raise TypeError(f"'{self.__class__.__name__}' object is not iterable")
```
**2. ConnectionAccessor** (after `__repr__` method, around line 355):
```python
def __iter__(self):
raise TypeError(f"'{self.__class__.__name__}' object is not iterable")
```
**3. MacrosAccessor** (after `__repr__` method, around line 439):
```python
def __iter__(self):
raise TypeError(f"'{self.__class__.__name__}' object is not iterable")
```
**Optional Enhancement** - Add dunder method protection in `__getattr__`
methods:
```python
def __getattr__(self, key: str) -> Any:
# Don't treat special methods (dunder methods) as variable/connection
names
if key.startswith('__') and key.endswith('__'):
raise AttributeError(f"'{self.__class__.__name__}' object has no
attribute '{key}'")
# ... rest of existing code
```
## Why This Works
- **Before**: `hasattr(obj, "__iter__")` → calls `__getattr__("__iter__")` →
tries to fetch variable → hang
- **After**: `hasattr(obj, "__iter__")` → returns `True` → calls
`obj.__iter__()` → raises `TypeError` → debugger handles gracefully
This follows Python's standard pattern for non-iterable objects.
## Testing Results
After applying this fix:
✅ Debugger works perfectly with `**context` parameters
✅ Variable access preserved: `context['var']['value'].my_var`
✅ Connection access preserved: `context['conn'].my_conn`
✅ Macro access preserved: `context['macros'].ds_add()`
✅ Works with VSCode, Zed debuggers (Problem did not seem to show on Pycharm)
✅ Tested on Airflow 3.0.2 and 3.1.3
## Temporary Workaround
Until this is fixed, users can:
1. Use named parameters: `def my_task(ti=None, ds=None):` instead of
`**context`
2. Disable variable inspection in debugger settings
3. Avoid breakpoints in functions with `**context`
## I'm Ready to Submit a PR
This is a minimal, non-breaking fix that only adds ~15 lines of code. Would
the maintainers like me to submit a PR with these changes?
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