Classic concurrency problem but the two-thread constraint is what makes it interesting.
Start by clarifying requirements (e.g., task priorities, cancellation, thread safety) and then propose a design using a thread-safe priority queue protected by a mutex, with condition variables for signaling between the scheduler and executor threads. Discuss trade-offs such as lock contention, fairness, and alternative approaches like lock-free queues or actor models.
Pro tip: Mention that descheduling requires a way to identify tasks (e.g., unique IDs) and that cancellation should be cooperative to avoid race conditions; also highlight the importance of graceful shutdown and handling exceptions in the executor thread.
Ask about task priorities, scheduling policies (FIFO, priority, deadline), descheduling semantics (cancel if not started, interrupt if running), and thread safety expectations.
Propose a thread-safe priority queue (e.g., heap) to store tasks, with each task having an ID, priority, and execution function. Use a mutex and condition variable to synchronize access.
The scheduler thread handles enqueue (schedule) and dequeue (deschedule) operations, while the executor thread waits for tasks and runs them. Use condition variables to signal when tasks are available or when the queue is empty.
Explain how to safely cancel tasks: if not started, remove from queue; if running, set a cancellation flag and let the task check it. Discuss locking granularity and potential deadlocks.
Compare mutex-based approach with lock-free queues, actor model, or thread pools. Mention scalability, latency, and complexity trade-offs.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.