Fix race condition in task replacement where duplicate executions occur#151
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chrisguidry merged 1 commit intomainfrom Aug 14, 2025
Merged
Fix race condition in task replacement where duplicate executions occur#151chrisguidry merged 1 commit intomainfrom
chrisguidry merged 1 commit intomainfrom
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Previously, `docket.replace()` could not cancel tasks that had already been moved from the queue to the stream by the scheduler, causing duplicate execution when the old task ran alongside the replacement. This happened because: 1. Scheduler moves due tasks from queue → stream, assigning Redis message IDs 2. `replace()` only checked the queue, missing tasks already in the stream 3. Both old and new tasks would execute This implements atomic task scheduling and cancellation using Lua scripts that track stream message IDs. The solution: - **Atomic scheduling**: New Lua script handles task existence checks, replacement cancellation, and scheduling in a single operation - **Stream message ID tracking**: When tasks move to stream, their message IDs are stored in the known task metadata - **Atomic cancellation**: Can delete tasks from stream using stored message IDs or from queue for scheduled tasks - **Race-free replacement**: Uses Redis locks per task key and atomic operations Comprehensive test coverage includes race condition scenarios and idempotent operations. Closes #149 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
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## main #151 +/- ##
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Files 31 31
Lines 4382 4411 +29
Branches 246 244 -2
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abrookins
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Aug 14, 2025
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| class _schedule_task(Protocol): | ||
| async def __call__( | ||
| self, keys: list[str], args: list[str | float | bytes] |
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This ... is a cool idea
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chrisguidry
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Aug 18, 2025
These fixes seem to get at least one of my systems into a state where it's infinitely looping on perpetual tasks. This may have been due to some of the intermediate problems in 0.9.0 and 0.9.1, but I don't want to take that chance. We'll come back and revisit this. This reverts commit 85f293c. Revert "Fix WRONGTYPE error and add memory leak detection tests (#153)" This reverts commit c2b8187. Revert "Fix race condition in task replacement where duplicate executions occur (#151)" This reverts commit 9dc405c.
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Fix race condition in task replacement where duplicate executions occur
Previously,
docket.replace()could not cancel tasks that had already been moved from the queue to the stream by the scheduler, causing duplicate execution when the old task ran alongside the replacement. This happened because:replace()only checked the queue, missing tasks already in the streamThis implements atomic task scheduling and cancellation using Lua scripts that track stream message IDs. The solution:
Comprehensive test coverage includes race condition scenarios and idempotent operations.
Closes #149
🤖 Generated with Claude Code