Unexpected behavior when fallback methods are called

Resilience4j version: 1.7.1 (resilience4j-spring-boot2)

Java version: 11 Spring Boot Version: 2.5.4

I tried combining @TimeLimiter and @CircuitBreaker with different fallback methods, like this:

   @Bulkhead(name = "getSearchResult", type = Type.THREADPOOL)
   @CircuitBreaker(name = "getSearchResult", fallbackMethod = "searchFailed")
   @TimeLimiter(name = "getSearchResult", fallbackMethod = "searchTimeout")
   public CompletableFuture<SearchResultData> getSearchResult(...) {...}

The two fallback methods have the same method signature as getSearchResult(...), plus a Throwable parameter.

Now, what happens is the following: In case of a timeout, searchTimeout(...) is called as expected, using a TimeoutException in the Throwable parameter. However, when no timeout occurs, but the method throws an exception, also searchTimeout(...) is called instead of searchFailed(...). The Throwable is then something else, as generated by getSearchResult(...).

Why is that? I would expect that timeouts lead to a call to searchTimeout(...) and other exceptions lead to a call to searchFailed(...).

[thomasschuerger]

When using TimeoutException in the searchTimeout(…) method signature, it works as expected. Thrown exceptions will lead to the exceptions being caught in searchFailed(…); if often enough, searchFailed() is called with a CallNotPermittedException and the protected method is not called, as expected.

In case of a timeout, searchTimeout(…) is called. If that happens often enough, searchFailed() is called with a CallNotPermittedException and the protected method is not called, as expected.

So no bug after all.

[thomasschuerger]

OK, good point. Both methods use Throwable. I’ll try using TimeoutException for searchTimeout(…).