Principle:Microsoft Autogen Round Robin Orchestration
| Knowledge Sources | |
|---|---|
| Domains | Multi-Agent Systems, Orchestration, Turn-Taking, AI Agents |
| Last Updated | 2026-02-11 00:00 GMT |
Overview
Round-robin orchestration is a deterministic turn-taking strategy in which multiple agents participate in a conversation by speaking in a fixed circular order, cycling through the participant list repeatedly until a termination condition is met.
Description
In multi-agent systems, an orchestrator (also called a group chat manager) controls which agent speaks next. Round-robin orchestration is the simplest orchestration strategy: it assigns turns to agents in the exact order they appear in the participant list, wrapping around to the first agent after the last one has spoken.
This approach provides several advantages:
- Determinism: The speaking order is entirely predictable. Given the same participant list, the same agent will always speak at the same position in the cycle. This makes debugging and testing straightforward.
- Fairness: Every agent gets an equal number of turns. No agent is starved of speaking opportunities and no agent dominates the conversation.
- Simplicity: No additional LLM calls or heuristics are needed to decide who speaks next. The overhead of orchestration is effectively zero.
- Composability: Round-robin teams can themselves be participants in higher-level teams, enabling hierarchical multi-agent architectures.
The trade-off is rigidity. The speaking order does not adapt to conversation context. If agent B's expertise is urgently needed but agent A is next in the rotation, agent A will still speak first. For context-sensitive turn selection, selector-based orchestration is more appropriate.
Round-robin orchestration is well-suited for:
- Pipeline workflows: Where each agent performs a distinct stage of processing (e.g., draft -> review -> edit -> finalize).
- Debate or discussion: Where agents take turns presenting arguments or perspectives.
- Iterative refinement: Where agents repeatedly improve upon each other's outputs.
- Simple two-agent conversations: Where two agents alternate turns, such as a user proxy and an assistant.
Usage
Use round-robin orchestration when you have a well-defined sequence of agent roles and want predictable, deterministic turn ordering. Prefer it over selector-based orchestration when the conversation flow is structured and does not require dynamic speaker selection.
Theoretical Basis
Round-robin orchestration implements a cyclic scheduler from operating systems theory, adapted for agent turn-taking. The algorithm is:
FUNCTION round_robin_select(participants, current_index):
1. next_index = (current_index + 1) MOD length(participants)
2. Return participants[next_index]
FUNCTION run_round_robin_conversation(participants, task, termination):
1. Initialize current_index = -1 (so first call yields index 0)
2. Send task to the group
3. LOOP:
a. Select next agent using round_robin_select
b. Agent processes conversation history and produces response
c. Broadcast response to all participants
d. Check termination condition against new messages
e. If termination triggered OR max_turns reached, STOP
f. Otherwise, continue to next iteration
4. Return conversation history and stop reason
The key property of this scheduler is O(1) selection cost -- determining the next speaker requires only a single modular arithmetic operation, regardless of the number of participants or the length of the conversation history.
The round-robin pattern also satisfies the fairness property: over any window of N consecutive turns (where N is the number of participants), each participant gets exactly one turn. This property holds regardless of termination timing or conversation length.
In a hierarchical architecture, a round-robin team can act as a single participant in a parent team. From the parent's perspective, the nested team is opaque -- it receives a task, runs its internal round-robin cycle, and returns a result. This enables building complex workflows from simple building blocks.