Fix when_all hang when some children complete before construction#1150
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sicoyle merged 1 commit intoJul 14, 2026
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WhenAllTask.__init__ was resetting _completed_tasks after CompositeTask had already counted pre-completed children, so deferred when_all hung forever in the partial-completion case. Signed-off-by: Patrick Assuied <patrick.assuied@elationhealth.com> Co-authored-by: Cursor <cursoragent@cursor.com>
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Pull request overview
This PR fixes a durabletask when_all(children) hang that occurs when some (but not all) child tasks complete before the WhenAllTask is constructed (deferred fan-in). It aligns WhenAllTask’s construction behavior with CompositeTask’s existing “count pre-completed children” initialization logic and adds regression coverage to prevent reintroduction.
Changes:
- Stop resetting
WhenAllTask’s_completed_tasks/_failed_tasksafterCompositeTask.__init__has already accounted for pre-completed children. - Add unit tests covering partial pre-completion, full pre-completion, and
when_any([when_all(children), timeout])interaction.
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Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
dapr/ext/workflow/_durabletask/task.py |
Removes the counter reset in WhenAllTask.__init__ so pre-completed children are retained and when_all can complete correctly. |
tests/ext/workflow/durabletask/test_task.py |
Adds regression tests for deferred when_all with pre-completed children and composition with when_any. |
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #1150 +/- ##
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+ Coverage 82.76% 82.84% +0.08%
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Files 123 123
Lines 10123 10121 -2
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+ Hits 8378 8385 +7
+ Misses 1745 1736 -9 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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JoshVanL
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Jul 14, 2026
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Jul 14, 2026
…1150) (#1151) WhenAllTask.__init__ was resetting _completed_tasks after CompositeTask had already counted pre-completed children, so deferred when_all hung forever in the partial-completion case. (cherry picked from commit 49eeda9) Signed-off-by: Patrick Assuied <patrick.assuied@elationhealth.com> Signed-off-by: dapr-bot <dapr-bot@users.noreply.github.com> Co-authored-by: Patrick Assuied <patrick.assuied@elationhealth.com> Co-authored-by: Cursor <cursoragent@cursor.com>
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Fixes #1149
Description
WhenAllTask.__init__was resetting_completed_tasks/_failed_tasksafterCompositeTask.__init__had already counted children that were complete at construction time. That drops early completions, so deferredwhen_all(children)hangs forever when some but not all children finished beforewhen_allwas built.Changes
WhenAllTask.__init__(keep empty-list fast path)when_any([when_all, timeout])Test plan
uv run pytest tests/ext/workflow/durabletask/test_task.pyRELEASE NOTE: FIX Bug causing
when_allto hang when some child tasks complete beforewhen_allis constructedMade with Cursor