Rosetta: fix some uncaught async exceptions causing 502s#18720
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glyh wants to merge 2 commits intocompatiblefrom
Open
Rosetta: fix some uncaught async exceptions causing 502s#18720glyh wants to merge 2 commits intocompatiblefrom
glyh wants to merge 2 commits intocompatiblefrom
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…uter The previous try...with only caught synchronous exceptions during deferred construction, missing exceptions raised inside async callbacks (e.g. Yojson.Basic.from_string in graphql.ml when the daemon returns a 200 with non-JSON body). Those escaped to on_handler_error and could crash the process. Monitor.try_with catches exceptions across the full async deferred chain. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
dkijania
approved these changes
Apr 3, 2026
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It would be nice to have some tests if current behavior is not covered |
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Problem
The Rosetta
/network/statusendpoint (and all other routes) was producing 502 errors under daemon stress. Two bugs combined to cause this:Bug 1 —
Yojson.Basic.from_stringcould throw an uncaught exception (graphql.ml)When the Mina daemon returns a HTTP 200 with a non-JSON body (e.g. during restart or under load),
Yojson.Basic.from_stringthrowsYojson.Json_error. This call lived inside an Async deferred callback, so it was never caught by the synchronoustry...withinrosetta.ml. The exception escaped toon_handler_error, leaving the HTTP connection in a broken state (or killing the process ifMINA_ROSETTA_TERMINATE_ON_SERVER_ERRORwas set) — both visible as 502s from any reverse proxy.Bug 2 —
try...withinrouterdoes not cover async exceptions (rosetta.ml)The top-level exception handler in
routerwas a plain OCamltry...with. In Async, this only catches exceptions raised synchronously during deferred construction. Any exception raised inside alet%bind/let%mapcallback fires later in the event loop, outside thetry...withscope, and propagates unhandled toon_handler_error.