pythongh-110666: Fix multiprocessing test_terminate() elapsed (python…

…GH-110667)

multiprocessing test_terminate() and test_wait_socket_slow() no
longer test the CI performance: no longer check maximum elapsed time.

Add CLOCK_RES constant: tolerate a difference of 100 ms.
(cherry picked from commit 1556f42)

Co-authored-by: Victor Stinner <vstinner@python.org>

Lib/test/_test_multiprocessing.py

@@ -84,6 +84,11 @@
     raise unittest.SkipTest("libasan has a pthread_create() dead lock related to thread+fork")
 
 
+# gh-110666: Tolerate a difference of 100 ms when comparing timings
+# (clock resolution)
+CLOCK_RES = 0.100
+
+
 def latin(s):
     return s.encode('latin')
 
@@ -1655,8 +1660,7 @@ def _test_waitfor_timeout_f(cls, cond, state, success, sem):
             dt = time.monotonic()
             result = cond.wait_for(lambda : state.value==4, timeout=expected)
             dt = time.monotonic() - dt
-            # borrow logic in assertTimeout() from test/lock_tests.py
-            if not result and expected * 0.6 <= dt:
+            if not result and (expected - CLOCK_RES) <= dt:
                 success.value = True
 
     @unittest.skipUnless(HAS_SHAREDCTYPES, 'needs sharedctypes')
@@ -2678,14 +2682,11 @@ def test_make_pool(self):
                 p.join()
 
     def test_terminate(self):
-        result = self.pool.map_async(
-            time.sleep, [0.1 for i in range(10000)], chunksize=1
-            )
+        # Simulate slow tasks which take "forever" to complete
+        args = [support.LONG_TIMEOUT for i in range(10_000)]
+        result = self.pool.map_async(time.sleep, args, chunksize=1)
         self.pool.terminate()
-        join = TimingWrapper(self.pool.join)
-        join()
-        # Sanity check the pool didn't wait for all tasks to finish
-        self.assertLess(join.elapsed, 2.0)
+        self.pool.join()
 
     def test_empty_iterable(self):
         # See Issue 12157
@@ -4870,7 +4871,7 @@ class TestWait(unittest.TestCase):
     def _child_test_wait(cls, w, slow):
         for i in range(10):
             if slow:
-                time.sleep(random.random()*0.1)
+                time.sleep(random.random() * 0.100)
             w.send((i, os.getpid()))
         w.close()
 
@@ -4910,7 +4911,7 @@ def _child_test_wait_socket(cls, address, slow):
         s.connect(address)
         for i in range(10):
             if slow:
-                time.sleep(random.random()*0.1)
+                time.sleep(random.random() * 0.100)
             s.sendall(('%s\n' % i).encode('ascii'))
         s.close()
 
@@ -4959,25 +4960,19 @@ def test_wait_socket_slow(self):
     def test_wait_timeout(self):
         from multiprocessing.connection import wait
 
-        expected = 5
+        timeout = 5.0  # seconds
         a, b = multiprocessing.Pipe()
 
         start = time.monotonic()
-        res = wait([a, b], expected)
+        res = wait([a, b], timeout)
         delta = time.monotonic() - start
 
         self.assertEqual(res, [])
-        self.assertLess(delta, expected * 2)
-        self.assertGreater(delta, expected * 0.5)
+        self.assertGreater(delta, timeout - CLOCK_RES)
 
         b.send(None)
-
-        start = time.monotonic()
         res = wait([a, b], 20)
-        delta = time.monotonic() - start
-
         self.assertEqual(res, [a])
-        self.assertLess(delta, 0.4)
 
     @classmethod
     def signal_and_sleep(cls, sem, period):