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FastAPI Production
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Module 5 · Production Deployment & Observability
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SSE and streaming responses
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📝 **Question:** Why send keepalive lines on an SSE stream? 📋 Pick the right answer. 💡 **Hint:** Re-read the theory above if unsure.
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📝 **Question:** Why send keepalive lines on an SSE stream? 📋 Pick the right answer. 💡 **Hint:** Re-read the theory above if unsure.
A
Browsers require a comment line at least every 30 seconds or they will close the EventSource connection with a network error, so the comment is purely a client-side compatibility requirement
B
Proxies (nginx, ALB, Cloudflare) close idle HTTP connections after 30-60s of silence
C
The SSE specification mandates a colon-prefixed line as the wire-level heartbeat — without it, conforming clients refuse to dispatch any events at all to the application layer above the parser
D
It exists only to make traffic visible during debugging — without periodic comments you can't tell whether the stream is healthy or just quiet, but production code can safely omit it entirely
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