fix/concurrency-thundering-herd - Branch - PrefectHQ/prefect

Use acquisition service pattern for lease-based concurrency slots

#19451

Comparing

fix/concurrency-thundering-herd

(

58b58a8

) with

main

(

6e30579

)

Untouched: 2

Ignored: 6

Benchmarks

Passed

bench_task_decorator

benches/bench_tasks.py

460.8 µs460.2 µs

bench_import_prefect_flow

benches/bench_import.py

1.4 s1.4 s

Ignored

bench_flow_call[options0]

benches/bench_flows.py

Ignored

+49%

165.2 ms110.9 ms

bench_task_submit

benches/bench_tasks.py

Ignored

-18%

5.7 ms6.9 ms

bench_flow_call[options1]

benches/bench_flows.py

Ignored

107.6 ms107.4 ms

bench_flow_decorator

benches/bench_flows.py

Ignored

+11%

6.3 ms5.7 ms

bench_import_prefect

benches/bench_import.py

Ignored

1.1 s1.1 s

bench_task_call

benches/bench_tasks.py

Ignored

-5%

158.1 ms166.9 ms

Commits

Click on a commit to change the comparison range

Base

main

6e30579

+0.03%

fix: serialize concurrency acquisition requests when requesting lease-based concurrency Adds ConcurrencySlotAcquisitionWithLeaseService to serialize acquisition attempts for lease-based concurrency limits. This prevents concurrent retry attempts when multiple tasks wait for available slots. The service uses a singleton pattern (one instance per unique set of limit names) with a single-threaded queue to process acquisition requests serially. This matches the pattern used by ConcurrencySlotAcquisitionService for non-lease-based concurrency. Benefits: - Prevents thundering herd when many tasks retry simultaneously - Reduces unnecessary API load - Improves slot acquisition efficiency - Adds limit names to debug logging for easier troubleshooting Related to ENGPAR-11 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>

58b58a8

2 days ago

by bunchesofdonald

Home Terms Privacy Docs