[Beta] RPC - Asynchronous User Functions
RPC Asynchronous User Functions supports the ability to yield and resume on the server side when executing a user-defined function. Prior to this feature, when a callee processes a request, one RPC thread waits until the user function returns. If the user function contains IO (e.g., nested RPC) or signaling (e.g., waiting for another request to unblock), the corresponding RPC thread would sit idle waiting for these events. As a result, some applications have to use a very large number of threads and send additional RPC requests, which can potentially lead to performance degradation. To make a user function yield on such events, applications need to: 1) Decorate the function with the @rpc.functions.async_execution decorator; and 2) Let the function return a torch.futures.Future and install the resume logic as callbacks on the Future object. See below for an example:
```python
@rpc.functions.async_execution
def async_add_chained(to, x, y, z):