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fix: handle unmapped task deadlock when upstream tasks are removed#62034

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kevinhongzl wants to merge 6 commits intoapache:mainfrom
kevinhongzl:fix-reducing-mapped-task-deadlock
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fix: handle unmapped task deadlock when upstream tasks are removed#62034
kevinhongzl wants to merge 6 commits intoapache:mainfrom
kevinhongzl:fix-reducing-mapped-task-deadlock

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@kevinhongzl
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@kevinhongzl kevinhongzl commented Feb 16, 2026


closes: #48816
related: #26518

(The previous fix went stale. Therefore, I open a new PR with tests completed.)

While the issue of deadlock caused by removing upstream mapped tasks has been addressed in #26518, that PR only handled cases where the downstream tasks were also mapped. This PR addresses the task deadlock occurring on downstream unmapped tasks.

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@kevinhongzl kevinhongzl force-pushed the fix-reducing-mapped-task-deadlock branch from 034b0e6 to e80b6b3 Compare February 16, 2026 17:03
@kevinhongzl kevinhongzl force-pushed the fix-reducing-mapped-task-deadlock branch from e80b6b3 to bd38d91 Compare February 21, 2026 14:30
@eladkal eladkal requested review from ephraimbuddy, kaxil and uranusjr and removed request for kaxil February 22, 2026 07:12
@eladkal eladkal added this to the Airflow 3.1.8 milestone Feb 22, 2026
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uranusjr commented Mar 3, 2026

Do we currently also have a test where neither the upstream nor the downstream is mapped? This would change the behaviour in that case, but the newly added test does not cover it.

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Reducing the number of mapped tasks causes a deadlock when executing the following normal tasks.

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