UT RE - enable for timer util (#506)

Summary:
Pull Request resolved: #506

# Context
[Describe motivations and existing situation that led to creating this diff. Don't be cheap with context, it is the basis for a good code review.]

# This diff
[List all the changes that this diff introduces and explain the ones that are not trivial. Give directions for the reviewer if needed.]

# What’s next
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Differential Revision: D48475432

fbshipit-source-id: 110a21e6dc08eaadb7ddd5055385193d9ea9ef1b

dev-requirements.txt

@@ -4,3 +4,4 @@ pytest-cov
 torchsnapshot-nightly
 pyre-check
 torchvision
+expecttest

tests/utils/test_timer.py

@@ -11,11 +11,11 @@
 from datetime import timedelta
 from random import random
 from unittest import mock
+from unittest.mock import patch
 
 import torch
 import torch.distributed as dist
-import torch.distributed.launcher as launcher
-from torchtnt.utils.test_utils import get_pet_launch_config
+from torch.testing._internal.common_distributed import spawn_threads_and_init_comms
 from torchtnt.utils.timer import (
     FullSyncPeriodicTimer,
     get_durations_histogram,
@@ -44,7 +44,8 @@ def test_timer_verbose(self) -> None:
             mock_info.assert_called_once()
             self.assertTrue("Testing timer took" in mock_info.call_args.args[0])
 
-    def test_timer_context_manager(self) -> None:
+    @patch("torch.cuda.synchronize")
+    def test_timer_context_manager(self, _) -> None:
         """Test the context manager in the timer class"""
 
         # Generate 3 intervals between 0.5 and 2 seconds
@@ -81,7 +82,8 @@ def test_timer_context_manager(self) -> None:
     @unittest.skipUnless(
         condition=torch.cuda.is_available(), reason="This test needs a GPU host to run."
     )
-    def test_timer_synchronize(self) -> None:
+    @patch("torch.cuda.synchronize")
+    def test_timer_synchronize(self, mock_synchornize) -> None:
         """Make sure that torch.cuda.synchronize() is called when GPU is present."""
 
         start_event = torch.cuda.Event(enable_timing=True)
@@ -97,11 +99,7 @@ def test_timer_synchronize(self) -> None:
 
         # torch.cuda.synchronize() has to be called to compute the elapsed time.
         # Otherwise, there will be runtime error.
-        elapsed_time_ms = start_event.elapsed_time(end_event)
-        self.assert_within_tolerance(timer.recorded_durations["action_1"][0], 0.5)
-        self.assert_within_tolerance(
-            timer.recorded_durations["action_1"][0], elapsed_time_ms / 1000
-        )
+        self.assertEqual(mock_synchornize.call_count, 2)
 
     def test_get_timer_summary(self) -> None:
         """Test the get_timer_summary function"""
@@ -166,7 +164,6 @@ def test_get_synced_durations_histogram(self) -> None:
 
     @staticmethod
     def _get_synced_durations_histogram_multi_process() -> None:
-        dist.init_process_group("gloo")
         rank = dist.get_rank()
         if rank == 0:
             recorded_durations = {
@@ -218,11 +215,9 @@ def _get_synced_durations_histogram_multi_process() -> None:
         condition=dist.is_available(),
         reason="This test should only run if torch.distributed is available.",
     )
+    @spawn_threads_and_init_comms(world_size=2)
     def test_get_synced_durations_histogram_multi_process(self) -> None:
-        config = get_pet_launch_config(2)
-        launcher.elastic_launch(
-            config, entrypoint=self._get_synced_durations_histogram_multi_process
-        )()
+        self._get_synced_durations_histogram_multi_process()
 
     def test_timer_fn(self) -> None:
         with log_elapsed_time("test"):
@@ -232,58 +227,38 @@ def test_timer_fn(self) -> None:
 class FullSyncPeriodicTimerTest(unittest.TestCase):
     @classmethod
     def _full_sync_worker_without_timeout(cls) -> bool:
-        dist.init_process_group("gloo")
         process_group = dist.group.WORLD
         interval_threshold = timedelta(seconds=5)
         fsp_timer = FullSyncPeriodicTimer(interval_threshold, process_group)
         return fsp_timer.check()
 
     @classmethod
     def _full_sync_worker_with_timeout(cls, timeout: int) -> bool:
-        dist.init_process_group("gloo")
         process_group = dist.group.WORLD
         interval_threshold = timedelta(seconds=5)
         fsp_timer = FullSyncPeriodicTimer(interval_threshold, process_group)
         time.sleep(timeout)
         fsp_timer.check()  # self._prev_work is assigned, next time the check is called, it will be executed
         return fsp_timer.check()  # Since 8>5, we will see flag set to True
 
+    @spawn_threads_and_init_comms(world_size=2)
     def test_full_sync_pt_multi_process_check_false(self) -> None:
-        config = get_pet_launch_config(2)
-        # Launch 2 worker processes. Each will check if time diff > interval threshold
-        result = launcher.elastic_launch(
-            config, entrypoint=self._full_sync_worker_without_timeout
-        )()
+        result = self._full_sync_worker_without_timeout()
         # Both processes should return False
-        self.assertFalse(result[0])
-        self.assertFalse(result[1])
+        self.assertFalse(result)
 
+    @spawn_threads_and_init_comms(world_size=2)
     def test_full_sync_pt_multi_process_check_true(self) -> None:
-        config = get_pet_launch_config(2)
-        # Launch 2 worker processes. Each will check time diff > interval threshold
-        result = launcher.elastic_launch(
-            config, entrypoint=self._full_sync_worker_with_timeout
-        )(8)
+        result = self._full_sync_worker_with_timeout(8)
         # Both processes should return True
-        self.assertTrue(result[0])
-        self.assertTrue(result[1])
+        self.assertTrue(result)
 
+    @spawn_threads_and_init_comms(world_size=2)
     def test_full_sync_pt_multi_process_edgecase(self) -> None:
-        config = get_pet_launch_config(2)
-        # Launch 2 worker processes. Each will check time diff >= interval threshold
-        result = launcher.elastic_launch(
-            config, entrypoint=self._full_sync_worker_with_timeout
-        )(5)
-
+        result = self._full_sync_worker_with_timeout(5)
         # Both processes should return True
-        self.assertTrue(result[0])
-        self.assertTrue(result[1])
-
-        # Launch 2 worker processes. Each will check time diff >= interval threshold
-        result = launcher.elastic_launch(
-            config, entrypoint=self._full_sync_worker_with_timeout
-        )(4)
+        self.assertTrue(result)
 
+        result = self._full_sync_worker_with_timeout(4)
         # Both processes should return False
-        self.assertFalse(result[0])
-        self.assertFalse(result[1])
+        self.assertFalse(result)