Characterize fast under saturation and contention

Characterize the behavior of the fast synchronous delivery mechanism under saturation and contention, including throughput across contention levels, chain depths, and message sizes, and the distribution of synchronous completions versus asynchronous fallbacks for fast_send_void.

Background

The reported microbenchmarks use sequential, single-message-in-flight tests and therefore do not establish how synchronous delivery behaves under sustained load or multi-core contention. The paper identifies the missing evaluation as including saturation, contention, throughput, chain depth, message size, and fallback behavior for the nonblocking best-effort operation. These conditions are especially important because contention can make blocking synchronous delivery worse than asynchronous enqueueing.

References

What this study does not establish, and what remains for future work, is behavior under saturation and contention: the evaluation here is sequential, single-machine, and socket-timestamped, not a throughput or multi-core stress test.

— Adapting the Actor Model of Concurrency for High-Frequency Trading: Synchronous Message Delivery (fast_send) and a Tick-to-Book Latency Study  (2609.21173 - Maciejewski, 18 Sep 2026) in Conclusion, final paragraph