Enable Torch Elastic Launch on Mast in D2go

Summary: Pull Request resolved: https://github.com/facebookresearch/d2go/pull/566

Reviewed By: wat3rBro

Differential Revision: D45829249

fbshipit-source-id: 4e70bed0e85179b49b4e2358be3d937cfbf474d4

d2go/distributed.py

@@ -73,6 +73,19 @@ def distributed_worker(
             shared_context
         )  # set the global shared context from the args passed in by mp spawn
     dist_params = dist_params or DistributedParams.from_environ()
+
+    if get_launch_environment() == "local" and not torch.cuda.is_available():
+        assert len(args) > 0, args
+        cfg = args[0]
+        if isinstance(cfg, CfgNode) and cfg.MODEL.DEVICE == "cuda":
+            logger.warning(
+                "Detected that CUDA is not available on this machine, set MODEL.DEVICE"
+                " to cpu and backend to GLOO"
+            )
+            with temp_defrost(cfg):
+                cfg.MODEL.DEVICE = "cpu"
+                args.backend = "GLOO"
+
     with enable_dist_process_groups(backend, init_method, dist_params, timeout):
         d2_comm._LOCAL_PROCESS_GROUP = mcv_comm._LOCAL_PROCESS_GROUP
         # Now the D2's comm module should be fully functional
@@ -106,19 +119,6 @@ def launch(
         - Automatically convert GPU to CPU if CUDA is not available.
         - Add D2Go-specific initialziation in the _distributed_worker.
     """
-
-    if get_launch_environment() == "local" and not torch.cuda.is_available():
-        assert len(args) > 0, args
-        cfg = args[0]
-        if isinstance(cfg, CfgNode) and cfg.MODEL.DEVICE == "cuda":
-            logger.warning(
-                "Detected that CUDA is not available on this machine, set MODEL.DEVICE"
-                " to cpu and backend to GLOO"
-            )
-            with temp_defrost(cfg):
-                cfg.MODEL.DEVICE = "cpu"
-        backend = "GLOO"
-
     return _launch(
         main_func=main_func,
         num_processes_per_machine=num_processes_per_machine,

d2go/setup.py

@@ -104,6 +104,7 @@ def basic_argument_parser(
             "--num-processes", type=int, default=1, help="number of gpus per machine"
         )
         parser.add_argument("--num-machines", type=int, default=1)
+        parser.add_argument("--run-as-worker", type=bool, default=False)
         parser.add_argument(
             "--machine-rank",
             type=int,
@@ -129,6 +130,7 @@ def build_basic_cli_args(
     dist_url: Optional[str] = None,
     dist_backend: Optional[str] = None,
     disable_post_mortem: bool = False,
+    run_as_worker: bool = False,
 ) -> List[str]:
     """
     Returns parameters in the form of CLI arguments for the binary using
@@ -147,6 +149,8 @@ def build_basic_cli_args(
         args += ["--save-return-file", str(save_return_file)]
     if disable_post_mortem:
         args += ["--disable-post-mortem"]
+    if run_as_worker:
+        args += ["--run-as-worker", str(run_as_worker)]
     if num_processes is not None:
         args += ["--num-processes", str(num_processes)]
     if num_machines is not None:

tools/train_net.py

@@ -11,7 +11,7 @@ from typing import List, Type, Union
 
 import detectron2.utils.comm as comm
 from d2go.config import CfgNode
-from d2go.distributed import launch
+from d2go.distributed import distributed_worker, launch
 from d2go.runner import BaseRunner
 from d2go.setup import (
     basic_argument_parser,
@@ -141,6 +141,23 @@ def run_with_cmdline_args(args):
     shared_context = setup_before_launch(cfg, output_dir, runner_name)
 
     main_func = main if args.disable_post_mortem else post_mortem_if_fail_for_main(main)
+
+    if args.run_as_worker:
+        logger.info("Running as worker")
+        result = distributed_worker(
+            main_func,
+            args=(cfg, output_dir, runner_name),
+            kwargs={
+                "eval_only": args.eval_only,
+                "resume": args.resume,
+            },
+            backend=args.dist_backend,
+            init_method=None,  # init_method is env by default
+            dist_params=None,
+            return_save_file=None,
+            shared_context=shared_context,
+        )
+    else:
         outputs = launch(
             main_func,
             num_processes_per_machine=args.num_processes,
@@ -155,10 +172,11 @@ def run_with_cmdline_args(args):
                 "resume": args.resume,
             },
         )
+        result = outputs[0]
 
     # Only save results from global rank 0 for consistency.
     if args.save_return_file is not None and args.machine_rank == 0:
-        save_binary_outputs(args.save_return_file, outputs[0])
+        save_binary_outputs(args.save_return_file, result)
 
 
 def cli(args=None):