Preserving Order in Concurrent Go Apps: Three Approaches Compared
9 days ago
- #Concurrency
- #Performance
- #Go
- Go's concurrency strength comes with a trade-off: unordered processing by default.
- Three scenarios where order matters: real-time log enrichment, finding the first match in a file list, and time series data processing.
- Three approaches to preserve order in concurrent processing: ReplyTo channels, sync.Cond for turn-taking, and permission passing chain.
- ReplyTo channels introduce up to 410ns overhead per item but perform well at higher concurrency levels.
- sync.Cond approach suffers from the 'thundering herd' problem, leading to significant performance degradation with more goroutines.
- Permission passing chain offers good performance (~500ns overhead), zero allocations, and clean abstractions for building ordered operations.
- Permission passing with channel pooling (Approach 3a) eliminates allocations while maintaining performance.
- Key takeaway: Permission passing is the best approach for ordered concurrency in Go, balancing performance, memory efficiency, and maintainability.