[legacy] clean up legacy code (#4743)

* [legacy] remove outdated codes of pipeline (#4692)

* [legacy] remove cli of benchmark and update optim (#4690)

* [legacy] remove cli of benchmark and update optim

* [doc] fix cli doc test

* [legacy] fix engine clip grad norm

* [legacy] remove outdated colo tensor (#4694)

* [legacy] remove outdated colo tensor

* [test] fix test import

* [legacy] move outdated zero to legacy (#4696)

* [legacy] clean up utils (#4700)

* [legacy] clean up utils

* [example] update examples

* [legacy] clean up amp

* [legacy] fix amp module

* [legacy] clean up gpc (#4742)

* [legacy] clean up context

* [legacy] clean core, constants and global vars

* [legacy] refactor initialize

* [example] fix examples ci

* [example] fix examples ci

* [legacy] fix tests

* [example] fix gpt example

* [example] fix examples ci

* [devops] fix ci installation

* [example] fix examples ci

colossalai/legacy/context/process_group_initializer/process_group_initializer.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+# -*- encoding: utf-8 -*-
+
+from abc import ABC, abstractmethod
+
+from colossalai.context import Config
+
+
+class ProcessGroupInitializer(ABC):
+    """An object, knowing the parallelism configuration, that initializes parallel groups.
+
+    Args:
+        rank (int): The rank of current process.
+        world_size (int): Size of whole communication world.
+        config (Config): Running configuration.
+        data_parallel_size (int): Size of data parallel.
+        pipeline_parallel_size (int): Size of pipeline parallel.
+        tensor_parallel_size (int): Size of tensor parallel.
+    """
+
+    def __init__(self, rank: int, world_size: int, config: Config, data_parallel_size: int, pipeline_parallel_size: int,
+                 tensor_parallel_size: int):
+        self.rank = rank
+        self.world_size = world_size
+        self.data_parallel_size = data_parallel_size
+        self.config = config
+        self.pipeline_parallel_size = pipeline_parallel_size
+        self.tensor_parallel_size = tensor_parallel_size
+        super().__init__()
+
+    @abstractmethod
+    def init_dist_group(self):
+        pass