fix: prevent head-of-line blocking in RedisWorker fetch_task() - #7977
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dkliban wants to merge 3 commits into
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fix: prevent head-of-line blocking in RedisWorker fetch_task()#7977dkliban wants to merge 3 commits into
dkliban wants to merge 3 commits into
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Track blocked resources across fetch_task() iterations and exclude them at the DB level using reserved_resources_record__overlap, leveraging the existing partial GIN index. This prevents workers from re-scanning thousands of blocked tasks when free resources exist further in the queue. Closes: pulp#7900 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
Fixes head-of-line blocking in RedisWorker.fetch_task() when thousands of
tasks need the same blocked resource (#7900).
After acquire_locks reports a resource as blocked, tasks needing that resource
are excluded from subsequent DB queries using reserved_resources_record overlap,
leveraging the existing partial GIN index. Both raw and shared: prefixed
variants are excluded.
Tests
Two test files:
Reproduction test (test_fetch_task_hol_blocking.py): 200 blocked tasks + 1 free task, asserts acquire_locks called <= 3 times. Fails on buggy code (6 calls), passes on fix (2 calls).
Scale test (test_fetch_task_scale.py): 2000 tasks across 50 resources with DB query assertions:
Fixes #7900
Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com