anil.recoil.org
A batteries included HTTP/1.1 client in OCaml
Close HTTP/2 connections after use to prevent Conpool reuse
When Conpool reuses a TCP connection for a second HTTP/2 request, the
code was attempting to send the HTTP/2 connection preface again, which
is invalid - you can only send the preface once per TCP connection.
This caused requests to hang.
The fix explicitly closes the flow after HTTP/2 request completion,
preventing Conpool from returning it to the idle pool. This is less
efficient than proper HTTP/2 multiplexing but ensures correctness.
Proper HTTP/2 connection reuse would require architectural changes to
tie H2_client state to TCP connections at the Conpool level.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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lib/requests.ml
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lib/requests.ml
···
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if is_h2 then begin
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(* Use HTTP/2 client via H2_adapter (handles caching and decompression) *)
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Log.debug (fun m -> m "Using HTTP/2 for %s (ALPN negotiated)" url_to_fetch);
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match H2_adapter.request
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let result = H2_adapter.request
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~flow:conn_info.flow
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~uri:uri_to_fetch
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~headers:headers_with_cookies
···
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~method_
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~auto_decompress:t.auto_decompress
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()
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-
with
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in
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(* Close the connection after HTTP/2 use to prevent Conpool from reusing it.
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HTTP/2 connection state (HPACK tables, flow control windows, stream IDs)
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is tied to the TCP connection, and we're not maintaining it across requests.
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Proper HTTP/2 multiplexing would require architectural changes to Conpool. *)
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Eio.Flow.close conn_info.flow;
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match result with
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| Ok resp -> (resp.H2_adapter.status, resp.H2_adapter.headers, resp.H2_adapter.body)
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| Error msg -> raise (Error.err (Error.Invalid_request { reason = "HTTP/2 error: " ^ msg }))
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end else begin