Remove `_fork_processes` from common_distributed.py (#63711)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63711

This removes `_fork_process` from common_distributed.py and fixes all
other callpoints to use `spawn_process` instead.
ghstack-source-id: 136395719

Test Plan: waitforbuildbot

Reviewed By: xush6528

Differential Revision: D30463834

fbshipit-source-id: 0c09e8a996d0e5b912c8cdd45488a39951bac4db

diff --git a/torch/testing/_internal/common_distributed.py b/torch/testing/_internal/common_distributed.py
index fb505d1..01e167f 100644 (file)
--- a/torch/testing/_internal/common_distributed.py
+++ b/torch/testing/_internal/common_distributed.py
@@ -9,7 +9,6 @@ import time
 import traceback
 import types
 import unittest
-import warnings
 from contextlib import contextmanager
 from datetime import timedelta
 from enum import Enum
@@ -468,14 +467,6 @@ class MultiProcessTestCase(TestCase):
             self.pid_to_pipe[process.pid] = parent_conn
             self.processes.append(process)
 
-    def _fork_processes(self) -> None:
-        warnings.warn(
-            "Fork based multiprocessing is dangerous and should not"
-            " be used, for tests with ASAN consider using opt-asan",
-            DeprecationWarning)
-        proc = torch.multiprocessing.get_context("fork").Process
-        self._start_processes(proc)
-
     def _spawn_processes(self) -> None:
         proc = torch.multiprocessing.get_context("spawn").Process
         self._start_processes(proc)