Federico Mariani created CAMEL-24137:
----------------------------------------
Summary: Circuit Breaker EIP - modernization umbrella (drop vavr,
async completion, virtual threads, duration units, breaker events)
Key: CAMEL-24137
URL: https://issues.apache.org/jira/browse/CAMEL-24137
Project: Camel
Issue Type: Improvement
Components: eip
Affects Versions: 4.21.0
Reporter: Federico Mariani
Attachments: camel-circuitbreaker-eip-review-2026-07.md
Umbrella for modernization suggestions from a review of the Circuit Breaker EIP
(core model, camel-resilience4j, camel-microprofile-fault-tolerance). Full
review document attached.
h3. Z1. Drop Vavr from camel-resilience4j
resilience4j 2.x removed its Vavr dependency, but camel-resilience4j re-adds
{{vavr}} + {{vavr-match}} 1.0.0 solely for one
{{Try.ofCallable(...).andThen(...).recover(...).get()}} chain in
{{ResilienceProcessor.process()}}. A plain try/catch removes two runtime jars.
h3. Z2. True async processing
Both processors implement the async contract but are fully blocking: they
always {{callback.done(true); return true}}, and the timeout path parks the
calling thread on {{future.get()}} while a second thread runs the work (two
threads per in-flight message). Resilience4j has CompletableFuture-based
decorators and SmallRye supports async guard calls; completing the
{{AsyncCallback}} from the worker would free consumer threads exactly when the
breaker is protecting a slow downstream - the scenario the EIP exists for.
h3. Z3. Virtual threads
The timeout executor (resilience4j) and thread-offload executor (FT) are
natural fits for virtual threads on JDK 21+ (Camel already has {{ThreadType}}
support in the ExecutorServiceManager); this would make the thread-per-call
model cheap even without Z2.
h3. Z4. Unit/type consistency in the resilience4j configuration model
{{waitDurationInOpenState}} and {{slowCallDurationThreshold}} are integer
*seconds*, while {{timeoutDuration}} and {{bulkheadMaxWaitDuration}} are
integer *millis*. The FT model already uses {{javaType=java.time.Duration}}
with {{parseDuration}} (accepts {{5s}}, {{500ms}}). Migrating the resilience4j
options to duration strings (with an upgrade-guide note) removes a recurring
user trap.
h3. Z5. Expose missing resilience4j 2.x features
* {{maxWaitDurationInHalfOpenState}};
* custom record/ignore predicate beans (currently only class-name lists);
* referencing existing {{TimeLimiter}} / {{Bulkhead}} beans (only
{{CircuitBreaker}} is referenceable today);
* optional ThreadPoolBulkhead;
* biggest observability win: bridge the resilience4j {{EventPublisher}} (state
transitions, not-permitted calls) to Camel events / a RoutePolicy hook, so
users do not have to poll JMX to learn the breaker opened.
h3. Z6. Deprecate {{onFallbackViaNetwork}}
Hystrix-era leftover; both remaining implementations throw
{{UnsupportedOperationException}} at route init. The DSL method and model
option exist only to fail.
h3. Z7. Clarify {{micrometerEnabled}} scope
It is only acted upon by camel-main's global {{detectResilience4jMicrometer}}
(reading the *default* configuration); set inline on a route's
{{resilience4jConfiguration}} it does nothing per-EIP. Document as global-only
or wire it per-processor.
h3. Z8. Test gaps
No test asserts {{RESPONSE_TIMED_OUT}} in either module; no pooled-mode test
with a consumer-created exchange (see CAMEL-24133); no test for fallback
visibility of guard-level exception causes.
_Filed by Claude Code on behalf of Federico Mariani (fmariani)_
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
