refactor diloco test

Summary:
- move the training loop to a separate file
- convert it into a class so that methods can be overridden without having to duplicate code

Author: tushar00jain

torchft/diloco_trainer.py

@@ -0,0 +1,310 @@
+import copy
+import logging
+import os
+from contextlib import ExitStack
+from datetime import timedelta
+from typing import Any, Dict, List, cast
+
+import torch
+from torch import nn
+from torch.distributed.tensor import DTensor
+
+from torchft.device_mesh import ManagedDeviceMesh, ft_init_device_mesh
+from torchft.local_sgd import DiLoCo
+from torchft.manager import Manager
+from torchft.manager_integ_test import MyModel, Runner
+from torchft.process_group import (
+    FakeProcessGroupWrapper,
+    ProcessGroupBabyNCCL,
+    ProcessGroupGloo,
+)
+
+logger: logging.Logger = logging.getLogger(__name__)
+
+
+class MultiModel(torch.nn.Module):
+    def __init__(self, in_dim: int = 3, out_dim: int = 4, n_layers: int = 1) -> None:
+        super().__init__()
+        self.layers = torch.nn.ModuleList()
+
+    def get_rand_inputs(
+        self, batch_size: int, device: torch.device = torch.device("cpu")
+    ) -> torch.Tensor:
+        raise
+
+    def get_rand_labels(
+        self, batch_size: int, device: torch.device = torch.device("cpu")
+    ) -> torch.Tensor:
+        raise
+
+
+class MultiMyModel(MultiModel):
+    def __init__(self, in_dim: int = 3, out_dim: int = 4, n_layers: int = 1) -> None:
+        super().__init__()
+        self.in_dim = in_dim
+
+        for _ in range(n_layers):
+            self.layers.append(MyModel(in_dim, out_dim))
+            in_dim, out_dim = out_dim, in_dim
+
+        self.out_dim = in_dim
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        for layer in self.layers:
+            x = layer(x)
+        return x
+
+    def get_rand_inputs(
+        self, batch_size: int, device: torch.device = torch.device("cpu")
+    ) -> torch.Tensor:
+        return torch.rand(batch_size, self.in_dim, device=device)
+
+    def get_rand_labels(
+        self, batch_size: int, device: torch.device = torch.device("cpu")
+    ) -> torch.Tensor:
+        return torch.randint(self.out_dim, (batch_size,), device=device)
+
+
+class DiLoCoTrainer:
+    """
+    A class that encapsulates the DiLoCo training process.
+    """
+
+    def __init__(
+        self,
+        rank: int,
+        store_port: int,
+        device: torch.device,
+        runner: Runner,
+        model_state_dict: dict[str, Any],
+        n_fragments: int,
+        diloco_args: dict[str, Any],
+    ) -> None:
+        """
+        Initialize the DiLoCoTrainer.
+
+        Args:
+            rank: The rank of the current process.
+            store_port: The port for the store.
+            device: The device to use for training.
+            runner: The runner instance.
+            train_loop_args: Additional arguments for the training loop.
+        """
+        self.rank: int = rank
+        self.store_port: int = store_port
+        self.device: torch.device = device
+        self.runner: Runner = runner
+
+        # Extract arguments from train_loop_args
+        self.model_state_dict: Dict[str, Any] = model_state_dict
+        self.n_fragments: int = n_fragments
+        self.diloco_args: dict[str, Any] = diloco_args
+
+        # Initialize components
+        self.model: MultiModel = self.setup_model()
+        self.inner_optimizer: torch.optim.Optimizer = self.setup_inner_optimizer()
+        self.outer_optimizers: list[torch.optim.Optimizer] = (
+            self.setup_outer_optimizers()
+        )
+
+        self.pg: FakeProcessGroupWrapper = self.setup_pg()
+        # Set up the process group for the event injector
+        self.runner.event_injector.set_pg(self.pg)
+
+        self.manager: Manager = self.setup_manager()
+
+        self.ft_device_mesh: None | ManagedDeviceMesh = None
+        self.setup_distributed()
+
+        self.criterion: nn.CrossEntropyLoss = nn.CrossEntropyLoss()
+
+        self.diloco: DiLoCo | None = None
+
+    def setup_model(self) -> MultiModel:
+        """Set up the model and move it to the device."""
+        model = MultiMyModel(2, 3, self.n_fragments)
+        model.load_state_dict(self.model_state_dict)
+        model.to(self.device)
+        return model
+
+    def setup_inner_optimizer(self) -> torch.optim.Optimizer:
+        """Set up the inner optimizer."""
+        return torch.optim.AdamW(
+            self.model.parameters(), lr=4e-4, weight_decay=0.1, betas=(0.9, 0.95)
+        )
+
+    def setup_outer_optimizers(self) -> list[torch.optim.Optimizer]:
+        """Set up outer optimizers."""
+        # Setup inner optimizer
+        # Create one outer optimizer per fragment
+        outer_optimizers = []
+        for _, layers in enumerate(self.model.layers):
+            outer_optimizers.append(
+                torch.optim.SGD(
+                    layers.parameters(), lr=0.7, momentum=0.9, nesterov=True
+                )
+            )
+        return outer_optimizers
+
+    def setup_pg(self) -> FakeProcessGroupWrapper:
+        if self.device.type == "cuda":
+            return FakeProcessGroupWrapper(ProcessGroupBabyNCCL())
+        else:
+            return FakeProcessGroupWrapper(
+                ProcessGroupGloo(timeout=timedelta(seconds=10))
+            )
+
+    def setup_manager(self) -> Manager:
+        """Set up the process group and manager."""
+        print(
+            f"worker {self.runner.replica_id=} {self.rank=} {self.runner.world_size=} starting"
+        )
+
+        # Create manager with all arguments passed directly
+        return Manager(
+            pg=self.pg,
+            min_replica_size=2,
+            use_async_quorum=False,
+            load_state_dict=self.load_state_dict,
+            state_dict=self.state_dict,
+            replica_id=str(self.runner.replica_id),
+            store_addr="localhost",
+            store_port=self.store_port,
+            rank=self.rank,
+            world_size=self.runner.world_size,
+            lighthouse_addr=self.runner.lighthouse_address,
+            port=19530 + self.runner.replica_id,
+            connect_timeout=timedelta(seconds=10),
+            quorum_timeout=timedelta(seconds=10),
+            timeout=timedelta(seconds=10),
+            **self.runner.manager_args,  # type: ignore
+        )
+
+    def setup_distributed(self) -> None:
+        """Set up distributed training."""
+        # Initialize default group for device mesh to work
+        if not torch.distributed.is_initialized():
+            # TODO: remove this try-except once pytorch is updated to 2.8.0 and can use localhost:0
+            try:
+                torch.distributed.init_process_group(
+                    init_method="tcp://localhost:0",
+                    rank=self.rank,
+                    world_size=self.runner.world_size,
+                )
+            except ValueError:
+                os.environ["MASTER_ADDR"] = "localhost"
+                os.environ["MASTER_PORT"] = "0"
+                os.environ["WORLD_SIZE"] = str(self.runner.world_size)
+                os.environ["RANK"] = str(self.rank)
+
+        self.ft_device_mesh = ft_init_device_mesh(
+            device_type=self.device.type,
+            mesh_shape=(self.runner.world_size, 1),
+            mesh_dim_names=("replicate", "none"),
+            replicate_dim=0,
+            manager=self.manager,
+        )
+
+        # Convert model parameters to DTensor
+        for layer in self.model.layers:
+            if isinstance(layer, nn.Linear):
+                for param in layer.parameters():
+                    param = DTensor.from_local(
+                        param,
+                        device_mesh=self.ft_device_mesh,
+                    )
+
+    def load_state_dict(self, state_dict: Dict[str, Dict[str, object]]) -> None:
+        """
+        Load the state dictionary.
+
+        Args:
+            state_dict: The state dictionary to load.
+        """
+        assert self.diloco is not None
+
+        self.model.load_state_dict(state_dict["model"])
+        self.model.to(self.device)
+
+        # Load original parameters for each fragment
+        for i, fragment in enumerate(cast(DiLoCo, self.diloco)._fragments):
+            fragment.original_parameters = cast(
+                Dict[str, torch.Tensor], state_dict["original_params"][f"{i}"]
+            )
+
+        for fragment in cast(DiLoCo, self.diloco)._fragments:
+            for name in fragment.original_parameters.keys():
+                fragment.original_parameters[name] = fragment.original_parameters[
+                    name
+                ].to(self.device)
+
+        self.inner_optimizer.load_state_dict(state_dict["inner_optim"])
+        for i, optimizer in enumerate(self.outer_optimizers):
+            optimizer.load_state_dict(
+                cast(dict[str, torch.Tensor], state_dict[f"outer_optim"][f"{i}"])
+            )
+
+    def state_dict(self) -> Dict[str, Dict[str, object]]:
+        """
+        Get the state dictionary.
+
+        Returns:
+            The state dictionary.
+        """
+        assert self.diloco is not None
+
+        return {
+            "model": self.model.state_dict(),
+            "original_params": {
+                f"{i}": fragment.original_parameters
+                for i, fragment in enumerate(cast(DiLoCo, self.diloco)._fragments)
+            },
+            "inner_optim": self.inner_optimizer.state_dict(),
+            "outer_optim": {
+                f"{i}": optimizer.state_dict()
+                for i, optimizer in enumerate(self.outer_optimizers)
+            },
+        }
+
+    def train_loop(self) -> dict[str, Any]:
+        """Run the training loop."""
+        # Ensure sync_every is set in diloco_args
+        all_state_dicts = {}
+
+        if "sync_every" not in self.diloco_args:
+            self.diloco_args["sync_every"] = 2
+
+        with DiLoCo(
+            self.manager,
+            [layer for layer in self.model.layers],
+            self.inner_optimizer,
+            self.outer_optimizers,
+            backup_device=self.device,
+            **self.diloco_args,
+        ) as self.diloco:
+            while True:
+                self.runner.event_injector.check(self.rank, self.manager.current_step())
+
+                manager_curr_step = self.manager.current_step()
+                if manager_curr_step not in all_state_dicts:
+                    # Store the manager state dict, converting to the right type
+                    all_state_dicts[manager_curr_step] = copy.deepcopy(
+                        self.manager._manager_state_dict()
+                    )
+
+                batch_size = 1
+                inputs = self.model.get_rand_inputs(batch_size, device=self.device)
+                labels = self.model.get_rand_labels(batch_size, device=self.device)
+
+                out = self.model(inputs)
+                loss = self.criterion(out, labels)
+
+                self.inner_optimizer.zero_grad()
+                loss.backward()
+                self.inner_optimizer.step()
+
+                # after 4 model updates then break
+                if self.manager.current_step() >= 4:
+                    break
+
+        return all_state_dicts