Why use IHttpClientFactory, and what problems can still occur with handler lifetime, DNS changes, and outbound concurrency?

IHttpClientFactory, handler lifetime, DNS, and socket reuse

Explains how IHttpClientFactory separates short-lived clients from pooled handlers and how concurrency, DNS, resilience, and DI lifetimes still require judgment.

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IHttpClientFactory centralizes outbound client configuration and pools underlying message handlers, so creating a factory client for an operation does not create a fresh TCP connection each time. Reusing handlers avoids socket exhaustion, while handler rotation lets new clients eventually observe DNS changes. Named or typed clients also keep base addresses, headers, logging, and resilience policies in one place. The factory does not make unlimited parallel requests safe or decide the correct timeout and retry policy for the dependency.

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IHttpClientFactory, HttpClient, SocketsHttpHandler, connection pooling, DNS refresh, handler lifetime, typed clients, resilience, and concurrency limits.

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Why this question matters
HttpClient lifetime advice sounds contradictory until the client object is separated from the underlying handler and connection pool. That distinction determines whether an API reuses sockets, observes DNS changes, and survives downstream load.
IHttpClientFactory centralizes outbound client configuration and pools underlying message handlers, so creating a factory client for an operation does not create a fresh TCP connection each time. Reusing handlers avoids socket exhaustion, while handler rotation lets new clients eventually observe DNS changes. Named or typed clients also keep base addresses, headers, logging, and resilience policies in one place. The factory does not make unlimited parallel requests safe or decide the correct timeout and retry policy for the dependency.
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I request the factory client when the operation needs it and avoid capturing a typed client inside a singleton longer than its handler lifetime. For very long-lived clients, a deliberately configured can recycle connections for DNS changes instead. I set an overall deadline, propagate cancellation, bound or upstream concurrency where needed, and retry only transient, replay-safe operations. Per-request headers and tokens stay on the request message rather than mutating shared default headers.

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Creating and disposing a raw handler for every request.
Capturing a typed client in a singleton indefinitely.
Assuming the factory limits outbound concurrency automatically.
Adding retries to non-idempotent writes without an operation design.

Why use IHttpClientFactory, and what problems can still occur with handler lifetime, DNS changes, and outbound concurrency?

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