CONC rules¶

The CONC domain addresses concurrency safety in async code: task and state ownership, proper lock usage, and race conditions.

These rules are planned. None of them is available in a release yet.

Background reading on the hazards these rules are meant to describe: Coroutines and Tasks and Developing with asyncio in the Python standard library documentation.

ID	Rule	Default	Concern
CONC001	Shared state across await	on	hazard
CONC002	Lock held across await	on	hazard
CONC003	Blocking call in async	on	hazard
CONC004	Concurrency primitive mismatch	on	hazard
CONC005	Detached task has no owner	on	hazard
CONC006	Inconsistent lock order	on	hazard
CONC007	Race or deadlock observed	observe	hazard
CONC008	Async shared scope mutation	on	hazard
CONC009	Async state has no task owner	on	hazard
CONC010	Async lifecycle is not awaited or closed	on	hazard
CONC011	External await has no timeout boundary	on	review
CONC012	Cancellation path can leave partial state	on	hazard

Rule details¶

Claim: risk
Detection/default: Shared state is read, an await occurs, then state is written from the stale read
Message template: counter is read before an await and written afterward, allowing another task to invalidate the update.

Claim: risk
Detection/default: Async code awaits while holding a lock or semaphore
Message template: {symbol} matches lock held across await: Async code awaits while holding a lock or semaphore.

Claim: risk
Detection/default: Async function reaches a known blocking primitive without delegation
Message template: {symbol} matches blocking call in async: Async function reaches a known blocking primitive without delegation.

Claim: risk
Detection/default: Coordination primitive is used outside the thread, task or process domain it protects
Message template: {symbol} matches concurrency primitive mismatch: Coordination primitive is used outside the thread, task or process domain it protects.

Claim: risk
Detection/default: Created task or submitted work has no retained, awaited or supervised handle
Message template: {symbol} matches detached task: Created task or submitted work has no retained, awaited or supervised handle.

Claim: risk
Detection/default: Different paths acquire the same locks in different orders
Message template: {symbol} matches inconsistent lock order: Different paths acquire the same locks in different orders.

Claim: defect
Detection/default: Instrumentation observes conflicting access, circular waiting or schedule-dependent failure
Message template: {symbol} matches race or deadlock observed: Instrumentation observes conflicting access, circular waiting or schedule-dependent failure.

Claim: risk
Detection/default: Async function writes a global or nonlocal binding
Message template: {symbol} matches async shared scope mutation: Async function writes a global or nonlocal binding.

Claim: risk
Detection/default: own + cf + (cg or run)
Message template: Three async functions mutate the same scope binding across suspension points without an identified task-local owner.

Claim: risk
Detection/default: An async iterator, context, stream, process, or client is created without an observed await/close/exit owner.
Message template: {resource} is created in {symbol} without an observed await, close, or async-context owner.

Claim: design
Detection/default: An external await is not dominated by a configured timeout or cancellation scope.
Message template: {symbol} awaits {effect} without an observed timeout or cancellation boundary.

Claim: risk
Detection/default: Owned state is mutated across a suspension point without rollback or cancellation-safe ordering.
Message template: {symbol} mutates {state} across an await, so cancellation can expose a partially completed transition.