@@ -5,6 +5,7 @@
 import logging
 import select
 import socket
+import sys
 import tempfile
 import threading
 import time
@@ -20,6 +21,10 @@
 from test.test_asyncio import utils as test_utils
 
 
+MACOS = (sys.platform == 'darwin')
+BUF_MULTIPLIER = 1024 if not MACOS else 64
+
+
 def tearDownModule():
     asyncio.set_event_loop_policy(None)
 
@@ -191,8 +196,8 @@ def test_create_server_ssl_1(self):
         TOTAL_CNT = 25    # total number of clients that test will create
         TIMEOUT = support.LONG_TIMEOUT  # timeout for this test
 
-        A_DATA = b'A' * 1024 * 1024
-        B_DATA = b'B' * 1024 * 1024
+        A_DATA = b'A' * 1024 * BUF_MULTIPLIER
+        B_DATA = b'B' * 1024 * BUF_MULTIPLIER
 
         sslctx = self._create_server_ssl_context(
             test_utils.ONLYCERT, test_utils.ONLYKEY
@@ -287,8 +292,8 @@ def test_create_connection_ssl_1(self):
         CNT = 0
         TOTAL_CNT = 25
 
-        A_DATA = b'A' * 1024 * 1024
-        B_DATA = b'B' * 1024 * 1024
+        A_DATA = b'A' * 1024 * BUF_MULTIPLIER
+        B_DATA = b'B' * 1024 * BUF_MULTIPLIER
 
         sslctx = self._create_server_ssl_context(
             test_utils.ONLYCERT,
@@ -1034,8 +1039,8 @@ def test_create_server_ssl_over_ssl(self):
         TOTAL_CNT = 25    # total number of clients that test will create
         TIMEOUT = support.LONG_TIMEOUT  # timeout for this test
 
-        A_DATA = b'A' * 1024 * 1024
-        B_DATA = b'B' * 1024 * 1024
+        A_DATA = b'A' * 1024 * BUF_MULTIPLIER
+        B_DATA = b'B' * 1024 * BUF_MULTIPLIER
 
         sslctx_1 = self._create_server_ssl_context(
             test_utils.ONLYCERT, test_utils.ONLYKEY)
@@ -1178,7 +1183,7 @@ def test_shutdown_cleanly(self):
         CNT = 0
         TOTAL_CNT = 25
 
-        A_DATA = b'A' * 1024 * 1024
+        A_DATA = b'A' * 1024 * BUF_MULTIPLIER
 
         sslctx = self._create_server_ssl_context(
             test_utils.ONLYCERT, test_utils.ONLYKEY)
 
@@ -0,0 +1,6 @@
+:source:`Lib/test/test_asyncio/test_ssl.py` exposed a bug in the macOS
+kernel where intense concurrent load on non-blocking sockets occasionally
+causes :const:`errno.ENOBUFS` ("No buffer space available") to be emitted.
+FB11063974 filed with Apple, in the mean time as a workaround buffer size
+used in tests on macOS is decreased to avoid intermittent failures.  Patch
+by Fantix King.