[rpc] split with dag (#2028)

* add DAG to split_module

* add comment

* add test case for DAG

* remove print

* add DAG middleware in scheduler

* add test case for scheduler

* remove break

* recover old lifecycle

Co-authored-by: Ziyue Jiang <ziyue.jiang@gmail.com>

colossalai/fx/passes/adding_split_node_pass.py

@@ -117,7 +117,7 @@ def uniform_split_pass(gm: torch.fx.GraphModule, pp_size: int):
     return gm
 
 
-def split_with_split_nodes_pass(annotated_gm: torch.fx.GraphModule):
+def split_with_split_nodes_pass(annotated_gm: torch.fx.GraphModule, merge_output=False):
     # TODO(lyl): use partition IR to assign partition ID to each node.
     # Currently: analyzing graph -> annotate graph by inserting split node -> use split module pass to split graph
     # In future: graph to partitions -> analyzing partition IR -> recombining partitions to get best performance -> assign partition ID to each node
@@ -129,7 +129,7 @@ def split_with_split_nodes_pass(annotated_gm: torch.fx.GraphModule):
             part_idx += 1
         return part_idx
 
-    split_mod = split_module(annotated_gm, None, split_callback)
+    split_mod = split_module(annotated_gm, None, split_callback, merge_output)
     split_submodules = []
     for name, submodule in split_mod.named_modules():
         if isinstance(submodule, torch.fx.GraphModule):

colossalai/fx/passes/utils.py

@@ -199,24 +199,17 @@ def find_user_in_partition(node, partitions, output_partitions=None, direct=Fals
         for partition in partitions:
             if node == partition:
                 user_partition_names.append(partition.name)
+                
     # find user with getitem call
     else:
         for partition in partitions:
             if node in partition.args:
                 user_partition_names.append(partition.name)
-    
-    is_output = False
-    def find_output(def_node, output_node):
-        nonlocal is_output
-        if def_node == output_node:
-            is_output = True
-        
+          
     if output_partitions is not None:
         output_node = output_partitions[0]
-        torch.fx.graph.map_arg(output_node.args[0], lambda n: find_output(node, n))
-    
-    if is_output:
-        user_partition_names.append('MODEL_OUTPUT')
+        if node.op == output_node.op:
+            user_partition_names.append('MODEL_OUTPUT')
     
     if len(user_partition_names) > 0:
         return user_partition_names

colossalai/pipeline/rpc/_pipeline_base.py

@@ -9,7 +9,7 @@ from typing import Any, Callable, Dict, List, Tuple
 import torch
 import torch.distributed.rpc as rpc
 from colossalai.pipeline.pipeline_process_group import ppg
-from colossalai.pipeline.rpc.utils import (get_batch_lengths, get_real_args_kwargs, pytree_filter, pytree_map,
+from colossalai.pipeline.rpc.utils import (get_batch_lengths, pytree_filter, pytree_map,
                                            split_batch, tensor_shape_list, type_detail)
 from torch import autograd, nn, optim
 from torch._C._distributed_rpc import PyRRef
@@ -20,7 +20,7 @@ class Phase(Enum):
     FORWARD = 0
     BACKWARD = 1
     UPDATE = 2
-
+    INPUT = 3
 
 class UniqueKey:
     __slots__ = ('microbatch_id', 'phase')
@@ -128,6 +128,7 @@ class WorkerBase(ABC):
         # topology info
         self.producer_stage_ids: List[int] = None
         self.consumer_stage_ids: List[int] = None
+        self.input_consumer_stage_ids: List[int] = None
 
         # module partitions
         self.partition_fn = partition_fn
@@ -135,6 +136,11 @@ class WorkerBase(ABC):
         self.criterion = criterion
         self.metric = metric
 
+        # middleware info
+        self._is_input = False
+        self._is_output = False
+        self._producer_consumer_initialized = False
+
         # context to maintain loop
         self._initialize_context_container()
 
@@ -164,6 +170,7 @@ class WorkerBase(ABC):
         self.work_list_condition_lock = threading.Condition(threading.Lock())
         self.output_list_condition_lock = threading.Condition(threading.Lock())
         self.label_lock = threading.Condition(threading.Lock())
+        self.producer_consumer_init_lock = threading.Condition(threading.Lock())
 
     def _initialize_partition(self):
         partition_fn = self.partition_fn
@@ -182,7 +189,7 @@ class WorkerBase(ABC):
         # construction of partition is executed after the registion of pp_rank_to_worker_rref
         self._initialize_partition()
 
-    def get_output_by_key(self, key: UniqueKey) -> Any:
+    def get_output_by_key(self, key: UniqueKey, recv_rank=None) -> Any:
         with self.output_list_condition_lock:
             self.output_list_condition_lock.wait_for(lambda: key in self.output_list)
             output_work_item = self.output_list[key]
@@ -191,8 +198,9 @@ class WorkerBase(ABC):
         if isinstance(output, Future):
             output = output.wait()
 
-        output_work_item.refcount += 1
+        # output_work_item.refcount += 1
 
+        # TODO(jiangziyue) redesign lifecycle management for DAG scheduler
         # all consumers have been satisfied, the work_item can be released
         with self.output_list_condition_lock:
             if output_work_item.refcount >= len(self.consumer_stage_ids):
@@ -215,8 +223,10 @@ class WorkerBase(ABC):
             self.partition_condition_lock.wait_for(lambda: hasattr(self, 'module_partition'))
             return self.module_partition.state_dict()
 
-    def _make_args_kwargs(self, microbatch):
+    def _make_args_kwargs(self, microbatch, merge=False):
         if isinstance(microbatch, dict):
+            if merge:
+                return list(microbatch.values()), {}
             return [], microbatch
         elif isinstance(microbatch, torch.Tensor):
             return [microbatch], {}
@@ -228,24 +238,70 @@ class WorkerBase(ABC):
                     kwargs.update(arg)
                 else:
                     args.append(arg)
+            if merge:
+                arg_lst = args
+                for arg in kwargs.values():
+                    arg_lst.append(arg)
+                return arg_lst, {}
             return args, kwargs
         else:
             raise TypeError(f"Input batch can be only dict, list, tuple or tensor, but receive {type(microbatch)}")
 
     # just for first pp_rank
+    # TODO(jiangziyue) Consider whether this function should be protected by Lock in DAG env.
+    # TODO(jiangziyue) Define a Class for DAG.
     def set_input(self, microbatch_id: int, microbatch: Tuple[Any], forward_only: bool):
         assert self.consumer_stage_ids is not None
         key = UniqueKey(microbatch_id, Phase.FORWARD)
         output = self._get_future_by_device()
+        
+        if not self.use_middleware():
+            # make args and kwargs
+            args, kwargs = self._make_args_kwargs(microbatch)
 
-        # make args and kwargs
-        args, kwargs = self._make_args_kwargs(microbatch)
+            work_item = WorkItem(self.pp_rank, Phase.FORWARD, args, kwargs, output, microbatch_id, None,
+                                self.num_microbatches, forward_only)
+            with self.work_list_condition_lock:
+                self.work_list[key] = work_item
+                self.work_list_condition_lock.notify_all()
+        else:
+            # make args and kwargs
+            arg_lst, _ = self._make_args_kwargs(microbatch, merge=True)
 
-        work_item = WorkItem(self.pp_rank, Phase.FORWARD, args, kwargs, output, microbatch_id, None,
-                             self.num_microbatches, forward_only)
-        with self.work_list_condition_lock:
-            self.work_list[key] = work_item
-            self.work_list_condition_lock.notify_all()
+            # first stage assign correct input into other stages
+            DAG = self.get_DAG()
+            DAG_node = DAG['input_partition']
+            self_input_offsets = []
+            recv_input_key = UniqueKey(microbatch_id, Phase.INPUT)
+            # notify rank which should receive extra input
+            offset = 0
+            for details in DAG_node.values():
+                for partition_name in details['output'].keys():
+                    recv_rank = self.partition_name_to_pp_rank(partition_name)
+                    if recv_rank == self.pp_rank:
+                        self_input_offsets.append(offset)
+                    elif recv_rank not in self.input_consumer_stage_ids:
+                        self.input_consumer_stage_ids.append(recv_rank)
+                offset += 1
+
+            # set input for self rank
+            self_arg_lst = []
+            for off in self_input_offsets:
+                self_arg_lst.append(arg_lst[off])
+
+            work_item = WorkItem(self.pp_rank, Phase.FORWARD, self_arg_lst, {}, output, microbatch_id, None,
+                                self.num_microbatches, forward_only)
+            with self.work_list_condition_lock:
+                self.work_list[key] = work_item
+                self.work_list_condition_lock.notify_all()
+
+            # put input tensor which other nodes need into output_list
+            work_item_remote = WorkItem(self.pp_rank, Phase.INPUT, [], {}, arg_lst, microbatch_id, None,
+                                self.num_microbatches, forward_only)
+
+            with self.output_list_condition_lock:
+                self.output_list[recv_input_key] = work_item_remote
+                self.output_list_condition_lock.notify_all()
 
     # just for last pp_rank
     def set_labels(self, microbatch_id: int, microlabels: Any):
@@ -268,33 +324,68 @@ class WorkerBase(ABC):
             self.work_list[key] = work_item
             self.work_list_condition_lock.notify_all()
 
+    # TODO(jiangziyue) Consider whether this function should be protected by Lock in DAG env.
     def subscribe_producer(self, microbatch_id: int, forward_only: bool):
         """
         You should call this function asynchronously
         """
-        assert self.producer_stage_ids is not None
-        producer_num = len(self.producer_stage_ids)
-        assert producer_num > 0, "only stage that has producers can subscribe producers"
-
         stage_id = self.pp_rank
-        subscribe_forward_futures: List[Future] = [None] * producer_num
         output = self._get_future_by_device()
+        if not self.use_middleware():
+            producer_num = len(self.producer_stage_ids)
+            subscribe_forward_futures: List[Future] = [None] * producer_num
+            for i in range(producer_num):
+                producer_stage_id = self.producer_stage_ids[i]
+                producer_output_key = UniqueKey(microbatch_id, Phase.FORWARD)
+                producer_worker_rref = self.pp_rank_to_worker_rref[producer_stage_id]
+                subscribe_forward_futures[i] = producer_worker_rref.rpc_async().get_output_by_key(producer_output_key)
+        else:
+            with self.work_list_condition_lock:
+                key = UniqueKey(microbatch_id, Phase.FORWARD)
+                if key in self.work_list:
+                    return
 
-        for i in range(producer_num):
-            producer_stage_id = self.producer_stage_ids[i]
-            producer_output_key = UniqueKey(microbatch_id, Phase.FORWARD)
-            producer_worker_rref = self.pp_rank_to_worker_rref[producer_stage_id]
-            subscribe_forward_futures[i] = producer_worker_rref.rpc_async().get_output_by_key(producer_output_key)
+            producer_stage_ids = []
+            with self.producer_consumer_init_lock:
+                self.producer_consumer_init_lock.wait_for(lambda: self._producer_consumer_initialized)
+                producer_stage_ids = self.producer_stage_ids
+            producer_num = len(producer_stage_ids)
+            
+            # TODO(jiangziyue) get single value instead of the whole output
+            if self.need_model_input():
+                producer_num += 1 # extra one(the last one) for input_tensor
+            subscribe_forward_futures: List[Future] = [None] * producer_num
+
+            # TODO(jiangziyue) get single value instead of the whole output
+            if self.need_model_input():
+                producer_stage_id = 0
+                producer_output_key = UniqueKey(microbatch_id, Phase.INPUT)
+                producer_worker_rref = self.pp_rank_to_worker_rref[producer_stage_id]
+                subscribe_forward_futures[0] = producer_worker_rref.rpc_async().get_output_by_key(producer_output_key, self.pp_rank)
+
+                for i in range(0, producer_num-1):
+                    producer_stage_id = producer_stage_ids[i]
+                    producer_output_key = UniqueKey(microbatch_id, Phase.FORWARD)
+                    producer_worker_rref = self.pp_rank_to_worker_rref[producer_stage_id]
+                    subscribe_forward_futures[i+1] = producer_worker_rref.rpc_async().get_output_by_key(producer_output_key, self.pp_rank)
+
+            else:
+                for i in range(producer_num):
+                    producer_stage_id = producer_stage_ids[i]
+                    producer_output_key = UniqueKey(microbatch_id, Phase.FORWARD)
+                    producer_worker_rref = self.pp_rank_to_worker_rref[producer_stage_id]
+                    #producer_partition_name = self.pp_rank_to_partition_name[producer_stage_id]
+                    subscribe_forward_futures[i] = producer_worker_rref.rpc_async().get_output_by_key(producer_output_key, self.pp_rank)
 
         work_item_from_producer = WorkItem(stage_id, Phase.FORWARD, subscribe_forward_futures, {}, output,
-                                           microbatch_id, None, self.num_microbatches, forward_only)
+                                        microbatch_id, None, self.num_microbatches, forward_only)
 
         # add work_item to work_list
         with self.work_list_condition_lock:
             key = UniqueKey(microbatch_id, Phase.FORWARD)
-            assert key not in self.work_list
-            self.work_list[key] = work_item_from_producer
-            self.work_list_condition_lock.notify_all()
+            if key not in self.work_list:
+                self.work_list[key] = work_item_from_producer
+                self.work_list_condition_lock.notify_all()
 
     def subscribe_consumer(self, microbatch_id: int):
         """
@@ -334,13 +425,132 @@ class WorkerBase(ABC):
         self.producer_stage_ids = []
         self.consumer_stage_ids = []
 
-        # Just for demo
-        prev_rank = rank - 1
-        next_rank = rank + 1
-        if prev_rank >= 0:
-            self.producer_stage_ids.append(prev_rank)
-        if next_rank <= self.actual_stage_num - 1:
-            self.consumer_stage_ids.append(next_rank)
+        if not self.use_middleware():
+            # Just for demo
+            prev_rank = rank - 1
+            next_rank = rank + 1
+            if prev_rank >= 0:
+                self.producer_stage_ids.append(prev_rank)
+            if next_rank <= self.actual_stage_num - 1:
+                self.consumer_stage_ids.append(next_rank)
+        else:
+            self.input_consumer_stage_ids = []
+            DAG = self.get_DAG()
+            DAG_node_name = self.pp_rank_to_partition_name(rank)
+            DAG_node = DAG[DAG_node_name]
+            for partition_name in DAG_node['input'].keys():
+                if partition_name == 'MODEL_INPUT':
+                    self._is_input = True
+                else:
+                    prev_rank = self.partition_name_to_pp_rank(partition_name)
+                    self.producer_stage_ids.append(prev_rank)
+
+            for partition_name in DAG_node['output'].keys():
+                if partition_name == 'MODEL_OUTPUT':
+                    self._is_output = True
+                else:
+                    next_rank = self.partition_name_to_pp_rank(partition_name)
+                    self.consumer_stage_ids.append(next_rank)
+                    
+            # TODO(jiangziyue) Consider whether this function should be protected by Lock in DAG env.
+            with self.producer_consumer_init_lock:
+                self._producer_consumer_initialized = True
+                self.producer_consumer_init_lock.notify_all()
+
+    # TODO(jiangziyue) Define a Class for DAG.
+    def pp_rank_to_partition_name(self, pp_rank: int):
+        prefix = 'submod_'
+        partition_name = prefix + str(pp_rank)
+        return partition_name
+
+    # TODO(jiangziyue) Define a Class for DAG.
+    def partition_name_to_pp_rank(self, partition_name: str) -> int:
+        prefix = 'submod_'
+        pp_rank = int(partition_name.split(prefix)[-1])
+        return pp_rank
+    
+    def get_DAG(self):
+        with self.partition_condition_lock:
+            self.partition_condition_lock.wait_for(lambda: hasattr(self, 'module_partition'))
+            if hasattr(self.module_partition, '_DAG'):
+                return self.module_partition._DAG
+            else:
+                return None
+    
+    def use_middleware(self):
+        DAG = self.get_DAG()
+        return DAG is not None
+
+    # TODO(jiangziyue) get single value instead of the whole output
+    def _get_real_args_kwargs(self, args_or_kwargs):
+        if not self.use_middleware():
+            args_or_kwargs = pytree_map(args_or_kwargs, fn=lambda x: x.wait(), process_types=Future)
+            if args_or_kwargs is not None:
+                if isinstance(args_or_kwargs, dict):
+                    pass
+                else:
+                    flatten_args = []
+                    pytree_map(args_or_kwargs, fn=lambda x: flatten_args.append(x), map_all=True)
+                    args_or_kwargs = flatten_args
+        else:
+            args_or_kwargs = pytree_map(args_or_kwargs, fn=lambda x: x.wait(), process_types=Future)
+            if args_or_kwargs is not None:
+                if isinstance(args_or_kwargs, dict):
+                    pass
+                else:
+                    flatten_args = []     
+                    if self.is_first_stage():
+                        pytree_map(args_or_kwargs, fn=lambda x: flatten_args.append(x), map_all=True)
+                    # TODO get by offset
+                    else:
+                        DAG = self.get_DAG()
+                        producer_outputs = {}
+                        cur_DAG_node_name = self.pp_rank_to_partition_name(self.pp_rank)
+                        #cur_DAG_node = DAG[self.pp_rank_to_partition_name(self.pp_rank)]
+                        for i, args_from_one_mod in enumerate(args_or_kwargs):
+                            producer_output_offsets = []
+                            if self.need_model_input():
+                                if i == 0:
+                                    producer_DAG_node = DAG['input_partition']
+                                    producer_partition_name = 'MODEL_INPUT'
+                                    offset = 0
+                                    for arg_info in producer_DAG_node.values():
+                                        if cur_DAG_node_name in arg_info['output']:
+                                            producer_output_offsets.append(offset)
+                                        offset += 1
+                                else:
+                                    producer_rank = self.producer_stage_ids[i-1]
+                                    producer_partition_name = self.pp_rank_to_partition_name(producer_rank)
+                                    producer_DAG_node = DAG[producer_partition_name]
+                                    producer_output_offsets = producer_DAG_node['output'][cur_DAG_node_name]
+
+                            else:
+                                producer_rank = self.producer_stage_ids[i]
+                                producer_partition_name = self.pp_rank_to_partition_name(producer_rank)
+                                producer_DAG_node = DAG[producer_partition_name]
+                                producer_output_offsets = producer_DAG_node['output'][cur_DAG_node_name]
+
+                            if producer_partition_name != 'MODEL_INPUT' and DAG[producer_partition_name]['output_len'] == 1:
+                                producer_outputs[producer_partition_name] = [args_from_one_mod]
+                            else:
+                                producer_outputs[producer_partition_name] = [args_from_one_mod[offset] for offset in producer_output_offsets]
+
+                        cur_DAG_node_input = DAG[cur_DAG_node_name]['input']
+
+                        def get_input_len(DAG_node_input):
+                            res = 0
+                            for offsets in DAG_node_input.values():
+                                res += len(offsets)
+                            return res
+
+                        input_len = get_input_len(cur_DAG_node_input)
+                        flatten_args = [None] * input_len
+                        for producer_partition_name, args_input_offsets in cur_DAG_node_input.items():
+                            for i, args_input_offset in enumerate(args_input_offsets):
+                                flatten_args[args_input_offset] = producer_outputs[producer_partition_name][i]
+
+                    args_or_kwargs = flatten_args
+        return args_or_kwargs
 
     @abstractmethod
     def _get_work_item_key(self) -> UniqueKey:
@@ -353,6 +563,9 @@ class WorkerBase(ABC):
 
     def is_last_stage(self):
         return self.pp_rank == self.actual_stage_num - 1
+    
+    def need_model_input(self):
+        return not self.is_first_stage() and self._is_input
 
     def _default_data_process_func(self, args_kwargs):
         if self.is_first_stage():
@@ -390,11 +603,11 @@ class WorkerBase(ABC):
 
             # parse and integrate args and kwargs
             if is_first_stage:
-                args = get_real_args_kwargs(args)
-                kwargs = get_real_args_kwargs(kwargs)
+                args = self._get_real_args_kwargs(args)
+                kwargs = self._get_real_args_kwargs(kwargs)
                 args_kwargs = (args, kwargs)
             else:
-                args_kwargs = get_real_args_kwargs(args)
+                args_kwargs = self._get_real_args_kwargs(args)
 
             args, kwargs = data_process_func(args_kwargs)
 
@@ -486,7 +699,7 @@ class WorkerBase(ABC):
 
             # overlap recompute and future.wait
             if not is_last_stage:
-                grad_tensors = get_real_args_kwargs(args)
+                grad_tensors = self._get_real_args_kwargs(args)
             else:
                 grad_tensors = None
 
@@ -569,7 +782,10 @@ class WorkerBase(ABC):
                 self._reset_context()
 
     def initialize_optimizer(self, optimizer_class: type, **kwargs):
-        self.optimizer: optim.Optimizer = optimizer_class(self.module_partition.parameters(), **kwargs)
+        # TODO(jiangziyue) it's temporary code to deal with empty module partition.
+        # After tracer fixed, remove this part.
+        if len(list(self.module_partition.parameters())) > 0:
+            self.optimizer: optim.Optimizer = optimizer_class(self.module_partition.parameters(), **kwargs)
         self.step_lock = threading.Lock()
         self.step_lock.acquire()
 
@@ -577,8 +793,11 @@ class WorkerBase(ABC):
         self.step_lock.acquire()
 
     def step(self):
-        self.optimizer.step()
-        self.optimizer.zero_grad()
+        # TODO(jiangziyue) it's temporary code to deal with empty module partition.
+        # After tracer fixed, remove this part.
+        if len(list(self.module_partition.parameters())) > 0:
+            self.optimizer.step()
+            self.optimizer.zero_grad()
         self.step_lock.release()