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expand dynamic mapped tasks in batches #29959

Description

@mksafavi

Description

expanding tasks in batches to allow mapped tasks spawn more than 1024 processes.

Use case/motivation

Maximum length of a list is limited to 1024 by max_map_length (AIRFLOW__CORE__MAX_MAP_LENGTH).
during scheduling of the new tasks, an UPDATE query is ran that tries to set all the new tasks at once. Increasing max_map_length more than 4K makes airflow scheduler completely unresponsive.

Also, Postgres throws stack depth limit exceeded error which can be fixed by updating to a newer version and setting max_stack_depth higher. But it doesn't really matter because airflow scheduler freezes up.

As a workaround, I split the dag runs into subdag runs which works but it would be much nicer if we didn't have to worry about exceeding max_map_length.

Related issues

It was discussed here:
Increasing 'max_map_length' leads to SQL 'max_stack_depth' error with 5000 dags to be spawned #28478

Are you willing to submit a PR?

  • Yes I am willing to submit a PR!

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