Settle WSGI producer exceptions truthfully - #28
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kentbull merged 1 commit intoAug 29, 2026
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Catch failures while invoking the application, constructing its iterator, and advancing response production so each path reaches an explicit terminal outcome. Render HTTPError only before response commitment, close the application-returned iterable before replacement output, and abort without rewriting queued bytes after commitment.
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Summary
Why
WSGI response production crosses three executable boundaries: calling the application, constructing the returned iterable iterator, and advancing that iterator. If an exception escapes or is only logged at any boundary, HIO cannot truthfully distinguish an active response from a failed one and may retain application resources. The HTTP commitment boundary also changes the only safe outcome: before headers, an
HTTPErrorcan become the response; after headers, replacing the response would corrupt the wire stream, so production must abort without rewriting queued bytes.Tracks ioflo#193. The upstream port is deferred behind ioflo#179, ioflo#181, ioflo#191, and ioflo#192. Body and terminal-frame enqueue failures remain isolated for the next unit.