[API] implement device mesh manager (#3221)

* [API] implement  device mesh manager

* polish

colossalai/cluster/device_mesh_manager.py

@@ -1,36 +1,117 @@
+from dataclasses import dataclass
+from typing import Dict, List, Tuple, Union
+
+import torch
+import torch.distributed as dist
+
+from colossalai.device.alpha_beta_profiler import AlphaBetaProfiler
 from colossalai.device.device_mesh import DeviceMesh
 
 
+@dataclass
+class DeviceMeshInfo:
+    '''
+    This class is used to store the information used to initialize the device mesh.
+
+    Args:
+        physical_ids (List[int]): The physical ids of the current booster. For example, if we have the last 4 GPUs on a 8-devices cluster, then the physical ids should be [4, 5, 6, 7].
+        mesh_shapes (List[Union[torch.Size, List[int], Tuple[int]]]): The shape of the mesh. For example, if we have 4 GPUs and we want to use 2D mesh with mesh shape [2, 2], then the mesh shape should be [2, 2].
+    '''
+    physical_ids: List[int]
+    mesh_shape: Union[torch.Size, List[int], Tuple[int]] = None
+
+    def __post_init__(self):
+        if self.mesh_shape is not None:
+            world_size = len(self.physical_ids)
+            mesh_shape_numel = torch.Size(self.mesh_shape).numel()
+            assert world_size == mesh_shape_numel, f'the numel of mesh_shape should be equal to world size, but got {world_size} != {mesh_shape_numel}'
+
+
+def initialize_device_mesh(device_mesh_info: DeviceMeshInfo):
+    '''
+    This method is used to initialize the device mesh.
+
+    Args:
+        device_mesh_info (DeviceMeshInfo): The information used to initialize device mesh.
+    '''
+    # parse the device mesh info
+    physical_devices = device_mesh_info.physical_ids
+    physical_mesh = torch.tensor(physical_devices)
+    logical_mesh_shape = device_mesh_info.mesh_shape
+
+    if logical_mesh_shape is None:
+        ab_profiler = AlphaBetaProfiler(physical_devices)
+        # search for the best logical mesh shape
+        logical_mesh_id = ab_profiler.search_best_logical_mesh()
+        logical_mesh_id = torch.Tensor(logical_mesh_id).to(torch.int)
+
+    else:
+        logical_mesh_id = physical_mesh.reshape(logical_mesh_shape)
+
+    device_mesh = DeviceMesh(physical_mesh_id=physical_mesh, logical_mesh_id=logical_mesh_id, init_process_group=True)
+    return device_mesh
+
+
 class DeviceMeshManager:
     """
     Device mesh manager is responsible for creating and managing device meshes.
     """
 
     def __init__(self):
-        self.device_mesh_store = dict()
+        self.device_mesh_store: Dict[str, DeviceMesh] = dict()
 
-    def create_device_mesh(self, name, *args, **kwargs) -> DeviceMesh:
+    def create_device_mesh(self, name, device_mesh_info: DeviceMeshInfo) -> DeviceMesh:
         """
         Create a device mesh and store it in the manager.
 
         Args:
             name (str): name of the device mesh
-            *args: args for DeviceMesh
-            **kwargs: kwargs for DeviceMesh
-        """
-        # TODO(Yuliang): replace *args, **kwargs with explicit arguments
+            device_mesh_info (DeviceMeshInfo): the information used to initialize the device mesh
+       """
         if name not in self.device_mesh_store:
-            device_mesh = DeviceMesh(*args, **kwargs)
+            device_mesh = initialize_device_mesh(device_mesh_info)
             self.device_mesh_store[name] = device_mesh
             return device_mesh
         else:
             raise ValueError(f'Device mesh {name} already exists.')
 
     def get(self, name: str) -> DeviceMesh:
-        pass
+        """
+        Get a device mesh by name.
 
-    def destroy(self):
-        pass
+        Args:
+            name (str): name of the device mesh
+
+        Returns:
+            DeviceMesh: the device mesh
+        """
+        if name in self.device_mesh_store:
+            return self.device_mesh_store[name]
+        else:
+            raise ValueError(f'Device mesh {name} does not exist.')
+
+    def destroy(self, name: str) -> None:
+        """
+        Destroy a device mesh by name.
+
+        Args:
+            name (str): name of the device mesh
+        """
+        if name in self.device_mesh_store:
+            for pgs in self.device_mesh_store[name].process_groups_dict.values():
+                for pg in pgs:
+                    dist.destroy_process_group(pg)
+            del self.device_mesh_store[name]
+        else:
+            raise ValueError(f'Device mesh {name} does not exist.')
 
     def destroy_all(self):
-        pass
+        """
+        Destroy all device meshes.
+        """
+        for name in self.device_mesh_store:
+            for pgs in self.device_mesh_store[name].process_groups_dict.values():
+                for pg in pgs:
+                    dist.destroy_process_group(pg)
+
+        self.device_mesh_store.clear()

tests/test_cluster/test_device_mesh_manager.py

@@ -0,0 +1,40 @@
+from functools import partial
+
+import torch
+import torch.multiprocessing as mp
+
+from colossalai.cluster.device_mesh_manager import DeviceMeshInfo, DeviceMeshManager
+from colossalai.device.device_mesh import DeviceMesh
+from colossalai.fx.tracer import ColoTracer
+from colossalai.initialize import launch
+from colossalai.logging import disable_existing_loggers
+from colossalai.utils import free_port
+
+
+def check_device_mesh_manager(rank, world_size, port):
+    disable_existing_loggers()
+    launch(config={}, rank=rank, world_size=world_size, host='localhost', port=port, backend='nccl')
+    device_mesh_manager = DeviceMeshManager()
+    device_mesh_info_auto = DeviceMeshInfo(physical_ids=[0, 1, 2, 3],)
+    device_mesh_auto = device_mesh_manager.create_device_mesh('0', device_mesh_info_auto)
+    assert device_mesh_auto.shape == (2, 2)
+    assert device_mesh_auto._logical_mesh_id.tolist() == [[0, 1], [2, 3]]
+
+    device_mesh_info_with_shape = DeviceMeshInfo(
+        physical_ids=[0, 1, 2, 3],
+        mesh_shape=(2, 2),
+    )
+    device_mesh_with_shape = device_mesh_manager.create_device_mesh('1', device_mesh_info_with_shape)
+
+    assert device_mesh_with_shape.shape == (2, 2)
+    assert device_mesh_with_shape._logical_mesh_id.tolist() == [[0, 1], [2, 3]]
+
+
+def test_device_mesh_manager():
+    world_size = 4
+    run_func = partial(check_device_mesh_manager, world_size=world_size, port=free_port())
+    mp.spawn(run_func, nprocs=world_size)
+
+
+if __name__ == '__main__':
+    test_device_mesh_manager()