How is the flow's thread pool described for a Synchronous flow?

• A. Fixed-size pool equal to one
• B. Elastic with one idle thread; tuning done at connector receiver level
• C. Shared with other flows
• D. Non-existent; runs on app thread

Answer: (B)

When a flow runs in a synchronous mode, it uses a thread pool that is elastic rather than fixed to a single thread. This means the pool can grow to handle multiple concurrent requests, improving throughput under load. The idea of having one idle thread ensures there’s always a thread ready to pick up a new incoming message without delay, helping reduce startup latency for requests.

Tuning is done at the receiver/connector level (for example, the HTTP listener or other inbound adapters) because those components control how many threads can poll for new messages and dispatch them to flows. The flow itself doesn’t decide its own thread count; it relies on the connector’s thread-pool settings to manage concurrency.

The other options don’t fit because a fixed-size pool of one would serialize processing and hurt performance, running on the app thread would imply no separate thread management, and sharing a pool with other flows isn’t the described behavior for synchronous flow threading in this context.