Reduce API server memory usage by eliminating SerializedDAG loads on task start
#60803
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SerializedDAG loads on task start
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…n task start Remove server-side computation of upstream_map_indexes from the Execution API. The Task SDK now computes these values locally when resolving XCom arguments for mapped task groups. This eliminates the need to load SerializedDAG on the API server for the /run endpoint, reducing memory usage and improving performance. Changes: - Add task_mapping.py with SDK-side computation logic - Remove upstream_map_indexes field from TIRunContext - Add Cadwyn migration for backward compatibility with older SDKs - Update xcom_arg.py and expandinput.py for lazy computation
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amoghrajesh
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Jan 20, 2026
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Makes sense. Didn't realise we had a todo in there
airflow-core/src/airflow/api_fastapi/execution_api/versions/v2026_03_31.py
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Remove server-side computation of upstream_map_indexes from the Execution API. The Task SDK now computes these values locally when resolving XCom arguments for mapped task groups.
Previously, every
/runrequest loaded the fullSerializedDAG(5-50MB) just to computeupstream_map_indexesfor XCom resolution in mapped task groups. This contributed to memory pressure on the API server.Now the Task SDK computes these values lazily when resolving XCom arguments, using the existing
GetTICountAPI to query task instance counts.Screenshots from tests:
Was generative AI tooling used to co-author this PR?
{pr_number}.significant.rstor{issue_number}.significant.rst, in airflow-core/newsfragments.