bpo-33532: Fix test_multiprocessing_forkserver.test_ignore() (GH-7323)

Use also support.SOCK_MAX_SIZE, not only support.PIPE_MAX_SIZE, to
get the size for a blocking send into a multiprocessing pipe.

Replace also test_support with support.

Lib/test/test_multiprocessing.py

@@ -16,16 +16,16 @@ import logging
 import errno
 import weakref
 import test.script_helper
-from test import test_support
+from test import support
 from StringIO import StringIO
-_multiprocessing = test_support.import_module('_multiprocessing')
+_multiprocessing = support.import_module('_multiprocessing')
 # import threading after _multiprocessing to raise a more relevant error
 # message: "No module named _multiprocessing". _multiprocessing is not compiled
 # without thread support.
 import threading
 
 # Work around broken sem_open implementations
-test_support.import_module('multiprocessing.synchronize')
+support.import_module('multiprocessing.synchronize')
 
 import multiprocessing.dummy
 import multiprocessing.connection
@@ -341,8 +341,8 @@ class _TestProcess(BaseTestCase):
         if self.TYPE == 'threads':
             self.skipTest('test not appropriate for {}'.format(self.TYPE))
 
-        testfn = test_support.TESTFN
-        self.addCleanup(test_support.unlink, testfn)
+        testfn = support.TESTFN
+        self.addCleanup(support.unlink, testfn)
 
         for reason, code in (([1, 2, 3], 1), ('ignore this', 1)):
             p = self.Process(target=self._test_sys_exit, args=(reason, testfn))
@@ -640,7 +640,7 @@ class _TestQueue(BaseTestCase):
             p.join()
 
     def test_no_import_lock_contention(self):
-        with test_support.temp_cwd():
+        with support.temp_cwd():
             module_name = 'imported_by_an_imported_module'
             with open(module_name + '.py', 'w') as f:
                 f.write("""if 1:
@@ -652,7 +652,7 @@ class _TestQueue(BaseTestCase):
                     q.close()
                 """)
 
-            with test_support.DirsOnSysPath(os.getcwd()):
+            with support.DirsOnSysPath(os.getcwd()):
                 try:
                     __import__(module_name)
                 except Queue.Empty:
@@ -1517,9 +1517,9 @@ class _TestRemoteManager(BaseTestCase):
               #'hall\xc3\xa5 v\xc3\xa4rlden'] # UTF-8
               ]
     result = values[:]
-    if test_support.have_unicode:
+    if support.have_unicode:
         #result[-1] = u'hall\xe5 v\xe4rlden'
-        uvalue = test_support.u(r'\u043f\u0440\u0438\u0432\u0456\u0442 '
+        uvalue = support.u(r'\u043f\u0440\u0438\u0432\u0456\u0442 '
                            r'\u0441\u0432\u0456\u0442')
         values.append(uvalue)
         result.append(uvalue)
@@ -1538,7 +1538,7 @@ class _TestRemoteManager(BaseTestCase):
         authkey = os.urandom(32)
 
         manager = QueueManager(
-            address=(test.test_support.HOST, 0), authkey=authkey, serializer=SERIALIZER
+            address=(test.support.HOST, 0), authkey=authkey, serializer=SERIALIZER
             )
         manager.start()
 
@@ -1575,7 +1575,7 @@ class _TestManagerRestart(BaseTestCase):
     def test_rapid_restart(self):
         authkey = os.urandom(32)
         manager = QueueManager(
-            address=(test.test_support.HOST, 0), authkey=authkey, serializer=SERIALIZER)
+            address=(test.support.HOST, 0), authkey=authkey, serializer=SERIALIZER)
         srvr = manager.get_server()
         addr = srvr.address
         # Close the connection.Listener socket which gets opened as a part
@@ -1786,13 +1786,13 @@ class _TestConnection(BaseTestCase):
         p = self.Process(target=self._writefd, args=(child_conn, b"foo"))
         p.daemon = True
         p.start()
-        with open(test_support.TESTFN, "wb") as f:
+        with open(support.TESTFN, "wb") as f:
             fd = f.fileno()
             if msvcrt:
                 fd = msvcrt.get_osfhandle(fd)
             reduction.send_handle(conn, fd, p.pid)
         p.join()
-        with open(test_support.TESTFN, "rb") as f:
+        with open(support.TESTFN, "rb") as f:
             self.assertEqual(f.read(), b"foo")
 
     @unittest.skipUnless(HAS_REDUCTION, "test needs multiprocessing.reduction")
@@ -1811,7 +1811,7 @@ class _TestConnection(BaseTestCase):
         p = self.Process(target=self._writefd, args=(child_conn, b"bar", True))
         p.daemon = True
         p.start()
-        with open(test_support.TESTFN, "wb") as f:
+        with open(support.TESTFN, "wb") as f:
             fd = f.fileno()
             for newfd in range(256, MAXFD):
                 if not self._is_fd_assigned(newfd):
@@ -1824,7 +1824,7 @@ class _TestConnection(BaseTestCase):
             finally:
                 os.close(newfd)
         p.join()
-        with open(test_support.TESTFN, "rb") as f:
+        with open(support.TESTFN, "rb") as f:
             self.assertEqual(f.read(), b"bar")
 
     @classmethod
@@ -2207,7 +2207,7 @@ class _TestFinalize(BaseTestCase):
             gc.set_threshold(5, 5, 5)
             threads = [threading.Thread(target=run_finalizers),
                        threading.Thread(target=make_finalizers)]
-            with test_support.start_threads(threads):
+            with support.start_threads(threads):
                 time.sleep(4.0)  # Wait a bit to trigger race condition
                 finish = True
             if exc:
@@ -2635,7 +2635,7 @@ class TestFlags(unittest.TestCase):
         flags = (tuple(sys.flags), grandchild_flags)
         print(json.dumps(flags))
 
-    @test_support.requires_unicode  # XXX json needs unicode support
+    @support.requires_unicode  # XXX json needs unicode support
     def test_flags(self):
         import json, subprocess
         # start child process using unusual flags
@@ -2681,6 +2681,9 @@ class TestForkAwareThreadLock(unittest.TestCase):
 
 class TestIgnoreEINTR(unittest.TestCase):
 
+    # Sending CONN_MAX_SIZE bytes into a multiprocessing pipe must block
+    CONN_MAX_SIZE = max(support.PIPE_MAX_SIZE, support.SOCK_MAX_SIZE)
+
     @classmethod
     def _test_ignore(cls, conn):
         def handler(signum, frame):
@@ -2689,7 +2692,7 @@ class TestIgnoreEINTR(unittest.TestCase):
         conn.send('ready')
         x = conn.recv()
         conn.send(x)
-        conn.send_bytes(b'x' * test_support.PIPE_MAX_SIZE)
+        conn.send_bytes(b'x' * cls.CONN_MAX_SIZE)
 
     @unittest.skipUnless(hasattr(signal, 'SIGUSR1'), 'requires SIGUSR1')
     def test_ignore(self):
@@ -2708,8 +2711,7 @@ class TestIgnoreEINTR(unittest.TestCase):
             self.assertEqual(conn.recv(), 1234)
             time.sleep(0.1)
             os.kill(p.pid, signal.SIGUSR1)
-            self.assertEqual(conn.recv_bytes(),
-                             b'x' * test_support.PIPE_MAX_SIZE)
+            self.assertEqual(conn.recv_bytes(), b'x' * self.CONN_MAX_SIZE)
             time.sleep(0.1)
             p.join()
         finally:
@@ -2766,7 +2768,7 @@ def test_main(run=None):
     check_enough_semaphores()
 
     if run is None:
-        from test.test_support import run_unittest as run
+        from test.support import run_unittest as run
 
     util.get_temp_dir()     # creates temp directory for use by all processes
 
@@ -2791,7 +2793,7 @@ def test_main(run=None):
     # module during these tests is at least platform dependent and possibly
     # non-deterministic on any given platform. So we don't mind if the listed
     # warnings aren't actually raised.
-    with test_support.check_py3k_warnings(
+    with support.check_py3k_warnings(
             (".+__(get|set)slice__ has been removed", DeprecationWarning),
             (r"sys.exc_clear\(\) not supported", DeprecationWarning),
             quiet=True):