Question 1

How do I handle long-running computations in Sento actors?

Accepted Answer

Avoid blocking in the receive function; use separate threads, third-party pools like lparallel, or the Tasks API with a custom dispatcher. Capture *sender* lexically for replies to ensure thread-safe responses, as explained in the README's section on asynchronous operations.

Question 2

What's the difference between ask and tell in Sento?

Accepted Answer

Tell is fire-and-forget with no response, while ask can be asynchronous (returns a future) or synchronous (blocks for a reply). Use tell for one-way messages and ask for request-response patterns, with timeout support for both.

Question 3

How does Sento compare to Akka or Erlang OTP?

Accepted Answer

Sento brings actor model concepts to Common Lisp with similar features like actors and FSMs, but has a smaller ecosystem and relies on OS threads rather than lightweight processes, making it less scalable for millions of actors compared to Erlang.

Question 4

Can I use Sento for distributed systems?

Accepted Answer

Yes, the remoting feature enables network communication between actor systems over TLS-secured connections, with remote actor references using sento:// URIs, allowing transparent message passing across machines.

Question 5

How to create a finite-state machine in Sento?

Accepted Answer

Use the make-fsm function with an event-handling lambda that defines states using macros like when-state and on-event. Specify start state, timeouts, and transitions, as shown in the traffic light controller example in the README.

Question 6

What are the performance benchmarks for Sento on SBCL?

Accepted Answer

Benchmarks in the README show high throughput for tell operations, but SBCL has issues with synchronous ask using shared dispatchers. Performance varies by operation type and Lisp implementation, with detailed charts for comparison.

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