Sample
Configure errgroup concurrency limits and semaphore capacity without zero-limit deadlocks, TryGo work dropping, unhandled dynamic limit reconfiguration panics, or zero-capacity Acquire hanging
sha256:76e608f62b6225cd144c98ac7e79f943331a1d88b9450ee339355970fa972627
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- go
- Operating system
- linux
- Architecture
- x64
- Runtime
- go
- Language
- go
- Package manager
- gomod
Verification-run environments
- Execution context
- go 1.26
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- go 1.26
- Language
- go
- Package manager
- gomod
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17
Case
- Goal
- Configure errgroup concurrency limits and semaphore capacity without zero-limit deadlocks, TryGo work dropping, unhandled dynamic limit reconfiguration panics, or zero-capacity Acquire hanging HOW
- Packages
-
golang.org/x/sync 0.22.0
- Environment
- go
- Created
- 2026-08-17T17:08:48Z
Commonly assumed
Configuring SetLimit(0) disables concurrency limits or safely rejects tasks, SetLimit can be updated dynamically at any time, and semaphore.Acquire immediately errors if requested weight exceeds capacity.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- assert configuring SetLimit(0) deadlocks errgroup.Go calls immediately and causes TryGo to drop 100% of submitted tasks rather than enabling unlimited concurrency
- assert configuring unlimited concurrency in errgroup strictly requires a negative limit such as SetLimit(-1) to reset the internal semaphore channel to nil
- assert reconfiguring SetLimit with a non-negative value while worker goroutines are actively running panics immediately with active worker count
- assert configuring semaphore.NewWeighted with 0 capacity causes Acquire to block indefinitely waiting for context cancellation rather than returning an immediate error
Files
- NOTES.md
- csx.json
- go.mod
- go.sum
- sync_test.go
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- go 1.26 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17 · ed25519:d91480838ac982c9