You are given a simplified distributed-computing setup that simulates communication between devices using Python threads and message queues. A helper class `Communicator` is available with the following behavior: - `send(src, dst, data)`: send a NumPy array from one device to another. - `recv(dst)`: block until device `dst` receives a message, then return `(src, data)`. Implement two functions for matrix multiplication `C = A @ B` using `num_devices` simulated devices. ## Part 1: Data Parallel multiplication Implement a per-device worker and the driver function for a data-parallel strategy: - Split matrix `A` row-wise into `num_devices` chunks. - Replicate the full matrix `B` to every device. - Each device computes its local output `A_chunk @ B`. - Gather all partial outputs to device `0` and concatenate them in the correct row order. - Return the full result matrix. Function signatures: - `compute_fn(comm, rank, a_chunk, b, result)` - `dp_mat_mul(a, b, num_devices)` ## Part 2: Fully Sharded multiplication Implement `fsdp_mat_mul(a, b, num_devices)` from scratch using a sharded strategy: - Split `A` row-wise across devices. - Split `B` column-wise across devices. - Each device initially owns one row shard of `A` and one column shard of `B`. - Use an all-gather style rotation of `B` shards: during each round, devices exchange `B` shards so that after all rounds, every device has multiplied its local `A` shard against every column shard of `B`. - Each device should accumulate the correct local output rows for its shard of `A`. - Finally, gather the row shards and return the full matrix `C`. ## Requirements - Use NumPy for matrix operations. - Use Python threads to simulate devices. - Use the provided `Communicator` for cross-device communication. - The final output must match `A @ B`. You may assume: - `A` has shape `(M, K)`. - `B` has shape `(K, N)`. - `num_devices >= 1`. - The row split of `A` and column split of `B` follow `numpy.array_split` semantics. Your implementation should correctly handle uneven splits as long as the shapes remain compatible.