Sync vs Async Inference - Interactive Visualization

Synchronous inference blocks the client thread until the model returns a prediction - simple, but every worker slot is occupied for the full inference duration. Asynchronous inference decouples request submission from result retrieval: the client receives a job_id immediately, then either polls or receives a webhook when the result is ready. The tradeoff is latency vs throughput under load. For inference times above ~500ms or concurrency above a few dozen requests per second, async patterns dramatically reduce tail latency and improve hardware utilization.

• Sync: one thread blocked per in-flight request - throughput limited to workers * (1000 / inference_ms)
• Async with polling: client repeatedly queries a job endpoint - adds round-trip overhead but frees the client thread immediately
• Async with webhooks: server pushes result when ready - lower overhead than polling, requires a publicly reachable callback URL
• Queue depth is the key warning signal: when events arrive faster than they are processed, latency grows unboundedly

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