Sample
anyio 4.13.0: Configuring abandon_on_cancel=False on anyio.to_thread.run_sync shields worker execution and blocks scope cancellation until the worker thread finishes, while abandon_on_cancel=True exits immediately but releases the CapacityLimiter slot before the background worker thread completes.
Verified sample for pypi anyio 4.13.0: Configuring abandon_on_cancel=False on anyio.to_thread.run_sync shields worker execution and blocks scope cancellation…
sha256:a14bcf1e15305a5701519193880ecabc0aab24fe04d053c597a482f66f869313
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
python linux x64 python python pip
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| python 3.12 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · python@1 |
2026-08-17 |
| python 3.12 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · python@1 |
2026-08-18 |
Case
HOW- Goal
- Configuring abandon_on_cancel=False on anyio.to_thread.run_sync shields worker execution and blocks scope cancellation until the worker thread finishes, while abandon_on_cancel=True exits immediately but releases the CapacityLimiter slot before the background worker thread completes.
- Packages
- Symbols
-
- anyio.to_thread.run_sync
- anyio.CapacityLimiter
- anyio.move_on_after
- Environment
- python
- Created
- 2026-08-17T11:44:01Z
Contract
- With abandon_on_cancel=False, cancelling the calling scope blocks until the worker thread finishes running, whereas abandon_on_cancel=True exits the scope immediately while releasing the CapacityLimiter before the synchronous thread finishes.
- assert cancel_scope.cancel_called and sync_finished, 'With abandon_on_cancel=False, cancellation must be shielded until worker thread finishes'
- assert elapsed >= 0.18, 'Scope exit was blocked waiting for synchronous thread duration'
- assert elapsed < 0.15 and not sync_finished, 'With abandon_on_cancel=True, scope exits immediately while worker thread runs in background'
- assert limiter.available_tokens == 1 and limiter.borrowed_tokens == 0, 'CapacityLimiter token is immediately released upon cancellation despite worker thread running'
- assert acquired_concurrently, 'Second task acquires limiter token concurrently with abandoned background thread'
- assert collision_caught, 'Calling run_sync while holding default limiter raises RuntimeError'
Files
- NOTES.md
- csx.json
- requirements.txt
- test/contract.py