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new a96c3273868 Warn agents against loading the serialized Dag on hot
paths (#75932)
a96c3273868 is described below
commit a96c327386812589643b544a861f2fec79ee237f
Author: Jason(Zhe-You) Liu <[email protected]>
AuthorDate: Sun Nov 1 17:29:15 2026 +0800
Warn agents against loading the serialized Dag on hot paths (#75932)
* Warn agents against loading the serialized Dag on hot paths
A performance regression reached 3.4.0 because ti_run deserialized the whole
serialized Dag on every task start to read two fields only a stub task
needs.
#75795 gated that load on ti.is_stub, but nothing recorded the rule, so the
next route to want a task attribute can reintroduce it just as easily.
* Clarify when to gate the serialized Dag load vs add a column
---------
---
airflow-core/src/airflow/api_fastapi/execution_api/AGENTS.md | 1 +
1 file changed, 1 insertion(+)
diff --git a/airflow-core/src/airflow/api_fastapi/execution_api/AGENTS.md
b/airflow-core/src/airflow/api_fastapi/execution_api/AGENTS.md
index 7e0cfecc7e3..146f8171022 100644
--- a/airflow-core/src/airflow/api_fastapi/execution_api/AGENTS.md
+++ b/airflow-core/src/airflow/api_fastapi/execution_api/AGENTS.md
@@ -32,6 +32,7 @@ uv run --active --group codegen --project
apache-airflow-task-sdk --directory ta
- Don't use keyword arguments with `endpoint()` — use positional:
`endpoint("/path", ["GET"])`.
- Don't add changes to already-released version files.
- Don't forget response converters for new fields in nested objects.
+- Don't load the serialized Dag unconditionally on a per-task hot path such as
`ti_run`. Gate the load so only the tasks that need it pay the cost (as
`ti.is_stub` does), and add a `task_instance` column only when every task needs
the value.
- Don't branch business logic by comparing the negotiated API version to a
date/version string. For this case, subclass `VersionChangeWithSideEffects` for
the version change and check its `is_applied` flag instead:
```python
