ActorContextAfterAwaitTests asserted that a ConfigureAwait(false)
continuation on the shared thread pool always throws NotSupportedException
when reading Self/Context. That property is a timing accident, not an Akka
guarantee: pool threads are exactly where Akka and the TestKit legitimately
install the [ThreadStatic] actor cell during mailbox runs and async
continuations, and Akka 1.5.62 has two non-throwing states besides — a
cleared cell makes ActorBase.Context return null (NullReferenceException on
.Self, not NotSupportedException) and ActorBase.Self return _clearedSelf
without any throw. Under parallel suite load the assertion failed once at
exactly that seam (2026-07-18); ironically the test's own doc comment said
the behaviour "does not reliably throw" and then asserted reliability.
The illegal reads now run on a dedicated new thread (LongRunning), the one
place the no-context state is guaranteed, while the realistic
ConfigureAwait(false) escape from the mailbox is kept. If the reads ever
unexpectedly succeed again, the failure message reports whose context the
thread was carrying. Verified 3 consecutive full-project runs green (38/38)
after 8 instrumented runs hunting the original repro.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
I dismissed this finding from the code review as a false positive, reasoning
that Akka's ActorBase caches Self in a field and that three passing
anti-entropy tests traverse the path. Both premises were wrong. Self resolves
through Context, which is [ThreadStatic], and throws NotSupportedException once
a continuation resumes on a thread-pool thread.
The tests passed because a local SQLite store usually completes await
SYNCHRONOUSLY, so the continuation stayed on the mailbox thread and the context
was still intact. Correctness therefore depended on store latency and
thread-pool timing: green here, broken under a slower or contended store, with
the only symptom a per-peer warning every announce interval while nodes
silently stopped converging. The live-broadcast fast path masked it further —
only the anti-entropy repair path was dead.
Captures self on the actor thread and passes it in. Adds
GenuinelyAsyncSecretStore to force the async path, a regression test that fails
on the unfixed code (20s timeout) and passes in 3s after, and
ActorContextAfterAwaitTests pinning the underlying Akka behaviour so the wrong
assumption cannot be made again. Audited every remaining Self/Sender access in
the actor.
170 pass offline / 184 with the live SQL suite / 1 skip / 0 warnings.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
Joseph Doherty