Fix HttpClientResponse body()/end() race (5.0 backport)#6071
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vietj merged 1 commit intoeclipse-vertx:5.0from Apr 17, 2026
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Fix HttpClientResponse body()/end() race (5.0 backport)#6071vietj merged 1 commit intoeclipse-vertx:5.0from
vietj merged 1 commit intoeclipse-vertx:5.0from
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This change fixes the race in `HttpClientResponseImpl` described in eclipse-vertx#6038: `handleTrailers()`/`handleException()` can run before `body()`/`end()` creates the promise. If that happens, the completion signal is dropped and the future can hang. This is observed from the call site as a HTTP request timeout. This fix is only applied to `HttpClientResponseImpl`: - keep ended/failure state on `HttpClientResponseImpl` - in `body()`/`end()`, create the `HttpEventHandler` promise while holding `synchronized(conn)` - after unlock, replay completion/failure via `handleEnd()`/`handleException()` when needed Although `HttpEventHandler` looks very similar (like it _could_ be affected by the same/similar race condition), it is not affected. I intentionally did not change `HttpEventHandler`, because it is also used in server request processing. The only case when server request processing could be affected , is when `body()` is called from a _different_ thread while `end()` is being processed - that is very unlikely (feels like a misuse). Also added two new tests to `Http1xTest` that reliably fail without the change to `HttpClientResponseImpl` and reliably pass with that change. The added regression tests are `testResponseBodyAfterResponseEnd` and `testResponseEndAfterResponseEnd`. Fixes eclipse-vertx#6038
vietj
approved these changes
Apr 16, 2026
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This change fixes the race in
HttpClientResponseImpldescribed in #6038:handleTrailers()/handleException()can run beforebody()/end()creates the promise. If that happens, the completion signal is dropped and the future can hang. This is observed from the call site as a HTTP request timeout.This fix is only applied to
HttpClientResponseImpl:HttpClientResponseImplbody()/end(), create theHttpEventHandlerpromise while holdingsynchronized(conn)handleEnd()/handleException()when neededAlthough
HttpEventHandlerlooks very similar (like it could be affected by the same/similar race condition), it is not affected. I intentionally did not changeHttpEventHandler, because it is also used in server request processing. The only case when server request processing could be affected , is whenbody()is called from a different thread whileend()is being processed - that is very unlikely (feels like a misuse).Also added two new tests to
Http1xTestthat reliably fail without the change toHttpClientResponseImpland reliably pass with that change. The added regression tests aretestResponseBodyAfterResponseEndandtestResponseEndAfterResponseEnd.Contributes to #6038