Atomic PythonActor spawn + init message #2426
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Differential Revision: D91829469
Summary: Pull Request resolved: meta-pytorch#2414 Add an optional `ndslice::Point` as an argument to `RemoteSpawn::new`. When an actor is spawned remotely as part of a proc mesh, the proc mesh agent will plumb the cast point through `RemoteSpawn::gspawn` so that the actor being spawned has access to its cast rank and coordinates when it is created. This will improve the experience for actors (like PythonActor) that need to know their position in an actor mesh before their full capabilities are available; previously, we would need to first spawn the actor, and then separately send a message with its cast point, which can cause race conditions. Differential Revision: D91663308
Summary: Pull Request resolved: meta-pytorch#2426 Currently, spawning a `PythonActor` happens in two stages -- first, we spawn the actors in the actor mesh; then, in a second, separate message, we construct the instance of the user's `Actor` implementation in python. This opens the door for a race condition where: 1. Actor A spawns a python actor mesh and passes a mesh ref to Actor B. 2. Actor B calls an endpoint on the mesh ref. 3. Actor B's message arrives in between actor spawn and the `Init` message from Actor A. 4. Actor B's call fails because the python actor thinks it hasn't been properly initialized yet. This PR solves the problem by processing the `Init` message as part of `PythonActor::init`, which is guaranteed to run before any other message is processed. This wasn't possible before meta-pytorch#2414 because we didn't have access to the point/rank of the actor until after `PythonActor::init`. Differential Revision: D91739758
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Summary:
Currently, spawning a
PythonActorhappens in two stages -- first, we spawn the actors in the actor mesh; then, in a second, separate message, we construct the instance of the user'sActorimplementation in python. This opens the door for a race condition where:Initmessage from Actor A.This PR solves the problem by processing the
Initmessage as part ofPythonActor::init, which is guaranteed to run before any other message is processed. This wasn't possible before #2414 because we didn't have access to the point/rank of the actor until afterPythonActor::init.Differential Revision: D91739758