diff --git a/Lib/test/test__opcode.py b/Lib/test/test__opcode.py
--- a/Lib/test/test__opcode.py
+++ b/Lib/test/test__opcode.py
@@ -20,6 +20,8 @@ def test_stack_effect(self):
         # All defined opcodes
         has_arg = dis.hasarg
         for name, code in filter(lambda item: item[0] not in dis.deoptmap, dis.opmap.items()):
+            if code >= opcode.MIN_INSTRUMENTED_OPCODE:
+                continue
             with self.subTest(opname=name):
                 if code not in has_arg:
                     stack_effect(code)
@@ -47,6 +49,8 @@ def test_stack_effect_jump(self):
         has_exc = dis.hasexc
         has_jump = dis.hasjabs + dis.hasjrel
         for name, code in filter(lambda item: item[0] not in dis.deoptmap, dis.opmap.items()):
+            if code >= opcode.MIN_INSTRUMENTED_OPCODE:
+                continue
             with self.subTest(opname=name):
                 if code not in has_arg:
                     common = stack_effect(code)
diff --git a/Lib/test/test_bdb.py b/Lib/test/test_bdb.py
--- a/Lib/test/test_bdb.py
+++ b/Lib/test/test_bdb.py
@@ -433,8 +433,9 @@ def __exit__(self, type_=None, value=None, traceback=None):
         not_empty = ''
         if self.tracer.set_list:
             not_empty += 'All paired tuples have not been processed, '
-            not_empty += ('the last one was number %d' %
+            not_empty += ('the last one was number %d\n' %
                           self.tracer.expect_set_no)
+            not_empty += repr(self.tracer.set_list)
 
         # Make a BdbNotExpectedError a unittest failure.
         if type_ is not None and issubclass(BdbNotExpectedError, type_):
diff --git a/Lib/test/test_code.py b/Lib/test/test_code.py
--- a/Lib/test/test_code.py
+++ b/Lib/test/test_code.py
@@ -349,14 +349,14 @@ def test_invalid_bytecode(self):
         def foo():
             pass
 
-        # assert that opcode 238 is invalid
-        self.assertEqual(opname[238], '<238>')
+        # assert that opcode 229 is invalid
+        self.assertEqual(opname[229], '<229>')
 
-        # change first opcode to 0xee (=238)
+        # change first opcode to 0xeb (=229)
         foo.__code__ = foo.__code__.replace(
-            co_code=b'\xee' + foo.__code__.co_code[1:])
+            co_code=b'\xe5' + foo.__code__.co_code[1:])
 
-        msg = f"unknown opcode 238"
+        msg = f"unknown opcode 229"
         with self.assertRaisesRegex(SystemError, msg):
             foo()
 
diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -479,8 +479,7 @@ async def _asyncwith(c):
            YIELD_VALUE              2
            RESUME                   3
            JUMP_BACKWARD_NO_INTERRUPT     5 (to 14)
-        >> SWAP                     2
-           POP_TOP
+        >> END_SEND
            POP_TOP
 
 %3d        LOAD_CONST               1 (1)
@@ -492,33 +491,32 @@ async def _asyncwith(c):
            CALL                     2
            GET_AWAITABLE            2
            LOAD_CONST               0 (None)
-        >> SEND                     3 (to 62)
+        >> SEND                     3 (to 60)
            YIELD_VALUE              2
            RESUME                   3
-           JUMP_BACKWARD_NO_INTERRUPT     5 (to 52)
-        >> POP_TOP
+           JUMP_BACKWARD_NO_INTERRUPT     5 (to 50)
+        >> END_SEND
            POP_TOP
 
 %3d        LOAD_CONST               2 (2)
            STORE_FAST               2 (y)
            RETURN_CONST             0 (None)
 
 %3d     >> CLEANUP_THROW
-           JUMP_BACKWARD           26 (to 24)
+           JUMP_BACKWARD           25 (to 24)
         >> CLEANUP_THROW
-           JUMP_BACKWARD            9 (to 62)
+           JUMP_BACKWARD            9 (to 60)
         >> PUSH_EXC_INFO
            WITH_EXCEPT_START
            GET_AWAITABLE            2
            LOAD_CONST               0 (None)
-        >> SEND                     4 (to 100)
+        >> SEND                     4 (to 98)
            YIELD_VALUE              3
            RESUME                   3
-           JUMP_BACKWARD_NO_INTERRUPT     5 (to 88)
+           JUMP_BACKWARD_NO_INTERRUPT     5 (to 86)
         >> CLEANUP_THROW
-        >> SWAP                     2
-           POP_TOP
-           POP_JUMP_IF_TRUE         1 (to 108)
+        >> END_SEND
+           POP_JUMP_IF_TRUE         1 (to 104)
            RERAISE                  2
         >> POP_TOP
            POP_EXCEPT
@@ -878,9 +876,9 @@ def test_boundaries(self):
 
     def test_widths(self):
         long_opcodes = set(['JUMP_BACKWARD_NO_INTERRUPT',
-                           ])
+                            'INSTRUMENTED_CALL_FUNCTION_EX'])
         for opcode, opname in enumerate(dis.opname):
-            if opname in long_opcodes:
+            if opname in long_opcodes or opname.startswith("INSTRUMENTED"):
                 continue
             with self.subTest(opname=opname):
                 width = dis._OPNAME_WIDTH
diff --git a/Lib/test/test_monitoring.py b/Lib/test/test_monitoring.py
new file mode 100644
--- /dev/null
+++ b/Lib/test/test_monitoring.py
@@ -0,0 +1,1044 @@
+"""Test suite for the sys.monitoring."""
+
+import collections
+import functools
+import operator
+import sys
+import types
+import unittest
+
+
+PAIR = (0,1)
+
+def f1():
+    pass
+
+def f2():
+    len([])
+    sys.getsizeof(0)
+
+def floop():
+    for item in PAIR:
+        pass
+
+def gen():
+    yield
+    yield
+
+def g1():
+    for _ in gen():
+        pass
+
+TEST_TOOL = 2
+TEST_TOOL2 = 3
+TEST_TOOL3 = 4
+
+class MonitoringBasicTest(unittest.TestCase):
+
+    def test_has_objects(self):
+        m = sys.monitoring
+        m.events
+        m.use_tool_id
+        m.free_tool_id
+        m.get_tool
+        m.get_events
+        m.set_events
+        m.get_local_events
+        m.set_local_events
+        m.register_callback
+        m.restart_events
+        m.DISABLE
+        m.MISSING
+        m.events.NO_EVENTS
+
+    def test_tool(self):
+        sys.monitoring.use_tool_id(TEST_TOOL, "MonitoringTest.Tool")
+        self.assertEqual(sys.monitoring.get_tool(TEST_TOOL), "MonitoringTest.Tool")
+        sys.monitoring.set_events(TEST_TOOL, 15)
+        self.assertEqual(sys.monitoring.get_events(TEST_TOOL), 15)
+        sys.monitoring.set_events(TEST_TOOL, 0)
+        with self.assertRaises(ValueError):
+            sys.monitoring.set_events(TEST_TOOL, sys.monitoring.events.C_RETURN)
+        with self.assertRaises(ValueError):
+            sys.monitoring.set_events(TEST_TOOL, sys.monitoring.events.C_RAISE)
+        sys.monitoring.free_tool_id(TEST_TOOL)
+        self.assertEqual(sys.monitoring.get_tool(TEST_TOOL), None)
+        with self.assertRaises(ValueError):
+            sys.monitoring.set_events(TEST_TOOL, sys.monitoring.events.CALL)
+
+
+class MonitoringTestBase:
+
+    def setUp(self):
+        # Check that a previous test hasn't left monitoring on.
+        for tool in range(6):
+            self.assertEqual(sys.monitoring.get_events(tool), 0)
+        self.assertIs(sys.monitoring.get_tool(TEST_TOOL), None)
+        self.assertIs(sys.monitoring.get_tool(TEST_TOOL2), None)
+        self.assertIs(sys.monitoring.get_tool(TEST_TOOL3), None)
+        sys.monitoring.use_tool_id(TEST_TOOL, "test " + self.__class__.__name__)
+        sys.monitoring.use_tool_id(TEST_TOOL2, "test2 " + self.__class__.__name__)
+        sys.monitoring.use_tool_id(TEST_TOOL3, "test3 " + self.__class__.__name__)
+
+    def tearDown(self):
+        # Check that test hasn't left monitoring on.
+        for tool in range(6):
+            self.assertEqual(sys.monitoring.get_events(tool), 0)
+        sys.monitoring.free_tool_id(TEST_TOOL)
+        sys.monitoring.free_tool_id(TEST_TOOL2)
+        sys.monitoring.free_tool_id(TEST_TOOL3)
+
+
+class MonitoringCountTest(MonitoringTestBase, unittest.TestCase):
+
+    def check_event_count(self, func, event, expected):
+
+        class Counter:
+            def __init__(self):
+                self.count = 0
+            def __call__(self, *args):
+                self.count += 1
+
+        counter = Counter()
+        sys.monitoring.register_callback(TEST_TOOL, event, counter)
+        if event == E.C_RETURN or event == E.C_RAISE:
+            sys.monitoring.set_events(TEST_TOOL, E.CALL)
+        else:
+            sys.monitoring.set_events(TEST_TOOL, event)
+        self.assertEqual(counter.count, 0)
+        counter.count = 0
+        func()
+        self.assertEqual(counter.count, expected)
+        prev = sys.monitoring.register_callback(TEST_TOOL, event, None)
+        counter.count = 0
+        func()
+        self.assertEqual(counter.count, 0)
+        self.assertEqual(prev, counter)
+        sys.monitoring.set_events(TEST_TOOL, 0)
+
+    def test_start_count(self):
+        self.check_event_count(f1, E.PY_START, 1)
+
+    def test_resume_count(self):
+        self.check_event_count(g1, E.PY_RESUME, 2)
+
+    def test_return_count(self):
+        self.check_event_count(f1, E.PY_RETURN, 1)
+
+    def test_call_count(self):
+        self.check_event_count(f2, E.CALL, 3)
+
+    def test_c_return_count(self):
+        self.check_event_count(f2, E.C_RETURN, 2)
+
+
+E = sys.monitoring.events
+
+SIMPLE_EVENTS = [
+    (E.PY_START, "start"),
+    (E.PY_RESUME, "resume"),
+    (E.PY_RETURN, "return"),
+    (E.PY_YIELD, "yield"),
+    (E.JUMP, "jump"),
+    (E.BRANCH, "branch"),
+    (E.RAISE, "raise"),
+    (E.PY_UNWIND, "unwind"),
+    (E.EXCEPTION_HANDLED, "exception_handled"),
+    (E.C_RAISE, "c_raise"),
+    (E.C_RETURN, "c_return"),
+]
+
+SIMPLE_EVENT_SET = functools.reduce(operator.or_, [ev for (ev, _) in SIMPLE_EVENTS], 0) | E.CALL
+
+
+def just_pass():
+    pass
+
+just_pass.events = [
+    "py_call",
+    "start",
+    "return",
+]
+
+def just_raise():
+    raise Exception
+
+just_raise.events = [
+    'py_call',
+    "start",
+    "raise",
+    "unwind",
+]
+
+def just_call():
+    len([])
+
+just_call.events = [
+    'py_call',
+    "start",
+    "c_call",
+    "c_return",
+    "return",
+]
+
+def caught():
+    try:
+        1/0
+    except Exception:
+        pass
+
+caught.events = [
+    'py_call',
+    "start",
+    "raise",
+    "exception_handled",
+    "branch",
+    "return",
+]
+
+def nested_call():
+    just_pass()
+
+nested_call.events = [
+    "py_call",
+    "start",
+    "py_call",
+    "start",
+    "return",
+    "return",
+]
+
+PY_CALLABLES = (types.FunctionType, types.MethodType)
+
+class MonitoringEventsBase(MonitoringTestBase):
+
+    def gather_events(self, func):
+        events = []
+        for event, event_name in SIMPLE_EVENTS:
+            def record(*args, event_name=event_name):
+                events.append(event_name)
+            sys.monitoring.register_callback(TEST_TOOL, event, record)
+        def record_call(code, offset, obj, arg):
+            if isinstance(obj, PY_CALLABLES):
+                events.append("py_call")
+            else:
+                events.append("c_call")
+        sys.monitoring.register_callback(TEST_TOOL, E.CALL, record_call)
+        sys.monitoring.set_events(TEST_TOOL, SIMPLE_EVENT_SET)
+        events = []
+        try:
+            func()
+        except:
+            pass
+        sys.monitoring.set_events(TEST_TOOL, 0)
+        #Remove the final event, the call to `sys.monitoring.set_events`
+        events = events[:-1]
+        return events
+
+    def check_events(self, func, expected=None):
+        events = self.gather_events(func)
+        if expected is None:
+            expected = func.events
+        self.assertEqual(events, expected)
+
+
+class MonitoringEventsTest(MonitoringEventsBase, unittest.TestCase):
+
+    def test_just_pass(self):
+        self.check_events(just_pass)
+
+    def test_just_raise(self):
+        try:
+            self.check_events(just_raise)
+        except Exception:
+            pass
+        self.assertEqual(sys.monitoring.get_events(TEST_TOOL), 0)
+
+    def test_just_call(self):
+        self.check_events(just_call)
+
+    def test_caught(self):
+        self.check_events(caught)
+
+    def test_nested_call(self):
+        self.check_events(nested_call)
+
+UP_EVENTS = (E.C_RETURN, E.C_RAISE, E.PY_RETURN, E.PY_UNWIND, E.PY_YIELD)
+DOWN_EVENTS = (E.PY_START, E.PY_RESUME)
+
+from test.profilee import testfunc
+
+class SimulateProfileTest(MonitoringEventsBase, unittest.TestCase):
+
+    def test_balanced(self):
+        events = self.gather_events(testfunc)
+        c = collections.Counter(events)
+        self.assertEqual(c["c_call"], c["c_return"])
+        self.assertEqual(c["start"], c["return"] + c["unwind"])
+        self.assertEqual(c["raise"], c["exception_handled"] + c["unwind"])
+
+    def test_frame_stack(self):
+        self.maxDiff = None
+        stack = []
+        errors = []
+        seen = set()
+        def up(*args):
+            frame = sys._getframe(1)
+            if not stack:
+                errors.append("empty")
+            else:
+                expected = stack.pop()
+                if frame != expected:
+                    errors.append(f" Popping {frame} expected {expected}")
+        def down(*args):
+            frame = sys._getframe(1)
+            stack.append(frame)
+            seen.add(frame.f_code)
+        def call(code, offset, callable, arg):
+            if not isinstance(callable, PY_CALLABLES):
+                stack.append(sys._getframe(1))
+        for event in UP_EVENTS:
+            sys.monitoring.register_callback(TEST_TOOL, event, up)
+        for event in DOWN_EVENTS:
+            sys.monitoring.register_callback(TEST_TOOL, event, down)
+        sys.monitoring.register_callback(TEST_TOOL, E.CALL, call)
+        sys.monitoring.set_events(TEST_TOOL, SIMPLE_EVENT_SET)
+        testfunc()
+        sys.monitoring.set_events(TEST_TOOL, 0)
+        self.assertEqual(errors, [])
+        self.assertEqual(stack, [sys._getframe()])
+        self.assertEqual(len(seen), 9)
+
+
+class CounterWithDisable:
+
+    def __init__(self):
+        self.disable = False
+        self.count = 0
+
+    def __call__(self, *args):
+        self.count += 1
+        if self.disable:
+            return sys.monitoring.DISABLE
+
+
+class RecorderWithDisable:
+
+    def __init__(self, events):
+        self.disable = False
+        self.events = events
+
+    def __call__(self, code, event):
+        self.events.append(event)
+        if self.disable:
+            return sys.monitoring.DISABLE
+
+
+class MontoringDisableAndRestartTest(MonitoringTestBase, unittest.TestCase):
+
+    def test_disable(self):
+        try:
+            counter = CounterWithDisable()
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, counter)
+            sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+            self.assertEqual(counter.count, 0)
+            counter.count = 0
+            f1()
+            self.assertEqual(counter.count, 1)
+            counter.disable = True
+            counter.count = 0
+            f1()
+            self.assertEqual(counter.count, 1)
+            counter.count = 0
+            f1()
+            self.assertEqual(counter.count, 0)
+            sys.monitoring.set_events(TEST_TOOL, 0)
+        finally:
+            sys.monitoring.restart_events()
+
+    def test_restart(self):
+        try:
+            counter = CounterWithDisable()
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, counter)
+            sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+            counter.disable = True
+            f1()
+            counter.count = 0
+            f1()
+            self.assertEqual(counter.count, 0)
+            sys.monitoring.restart_events()
+            counter.count = 0
+            f1()
+            self.assertEqual(counter.count, 1)
+            sys.monitoring.set_events(TEST_TOOL, 0)
+        finally:
+            sys.monitoring.restart_events()
+
+
+class MultipleMonitorsTest(MonitoringTestBase, unittest.TestCase):
+
+    def test_two_same(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            counter1 = CounterWithDisable()
+            counter2 = CounterWithDisable()
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, counter1)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_START, counter2)
+            sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+            sys.monitoring.set_events(TEST_TOOL2, E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL), E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL2), E.PY_START)
+            self.assertEqual(sys.monitoring._all_events(), {'PY_START': (1 << TEST_TOOL) | (1 << TEST_TOOL2)})
+            counter1.count = 0
+            counter2.count = 0
+            f1()
+            count1 = counter1.count
+            count2 = counter2.count
+            self.assertEqual((count1, count2), (1, 1))
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.set_events(TEST_TOOL2, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, None)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_START, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+
+    def test_three_same(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            counter1 = CounterWithDisable()
+            counter2 = CounterWithDisable()
+            counter3 = CounterWithDisable()
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, counter1)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_START, counter2)
+            sys.monitoring.register_callback(TEST_TOOL3, E.PY_START, counter3)
+            sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+            sys.monitoring.set_events(TEST_TOOL2, E.PY_START)
+            sys.monitoring.set_events(TEST_TOOL3, E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL), E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL2), E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL3), E.PY_START)
+            self.assertEqual(sys.monitoring._all_events(), {'PY_START': (1 << TEST_TOOL) | (1 << TEST_TOOL2) | (1 << TEST_TOOL3)})
+            counter1.count = 0
+            counter2.count = 0
+            counter3.count = 0
+            f1()
+            count1 = counter1.count
+            count2 = counter2.count
+            count3 = counter3.count
+            self.assertEqual((count1, count2, count3), (1, 1, 1))
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.set_events(TEST_TOOL2, 0)
+            sys.monitoring.set_events(TEST_TOOL3, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, None)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_START, None)
+            sys.monitoring.register_callback(TEST_TOOL3, E.PY_START, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+
+    def test_two_different(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            counter1 = CounterWithDisable()
+            counter2 = CounterWithDisable()
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, counter1)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_RETURN, counter2)
+            sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+            sys.monitoring.set_events(TEST_TOOL2, E.PY_RETURN)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL), E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL2), E.PY_RETURN)
+            self.assertEqual(sys.monitoring._all_events(), {'PY_START': 1 << TEST_TOOL, 'PY_RETURN': 1 << TEST_TOOL2})
+            counter1.count = 0
+            counter2.count = 0
+            f1()
+            count1 = counter1.count
+            count2 = counter2.count
+            self.assertEqual((count1, count2), (1, 1))
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.set_events(TEST_TOOL2, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, None)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_RETURN, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+
+    def test_two_with_disable(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            counter1 = CounterWithDisable()
+            counter2 = CounterWithDisable()
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, counter1)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_START, counter2)
+            sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+            sys.monitoring.set_events(TEST_TOOL2, E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL), E.PY_START)
+            self.assertEqual(sys.monitoring.get_events(TEST_TOOL2), E.PY_START)
+            self.assertEqual(sys.monitoring._all_events(), {'PY_START': (1 << TEST_TOOL) | (1 << TEST_TOOL2)})
+            counter1.count = 0
+            counter2.count = 0
+            counter1.disable = True
+            f1()
+            count1 = counter1.count
+            count2 = counter2.count
+            self.assertEqual((count1, count2), (1, 1))
+            counter1.count = 0
+            counter2.count = 0
+            f1()
+            count1 = counter1.count
+            count2 = counter2.count
+            self.assertEqual((count1, count2), (0, 1))
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.set_events(TEST_TOOL2, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.PY_START, None)
+            sys.monitoring.register_callback(TEST_TOOL2, E.PY_START, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+            sys.monitoring.restart_events()
+
+class LineMonitoringTest(MonitoringTestBase, unittest.TestCase):
+
+    def test_lines_single(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            events = []
+            recorder = RecorderWithDisable(events)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, recorder)
+            sys.monitoring.set_events(TEST_TOOL, E.LINE)
+            f1()
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, None)
+            start = LineMonitoringTest.test_lines_single.__code__.co_firstlineno
+            self.assertEqual(events, [start+7, 14, start+8])
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+            sys.monitoring.restart_events()
+
+    def test_lines_loop(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            events = []
+            recorder = RecorderWithDisable(events)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, recorder)
+            sys.monitoring.set_events(TEST_TOOL, E.LINE)
+            floop()
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, None)
+            start = LineMonitoringTest.test_lines_loop.__code__.co_firstlineno
+            self.assertEqual(events, [start+7, 21, 22, 22, 21, start+8])
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+            sys.monitoring.restart_events()
+
+    def test_lines_two(self):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            events = []
+            recorder = RecorderWithDisable(events)
+            events2 = []
+            recorder2 = RecorderWithDisable(events2)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, recorder)
+            sys.monitoring.register_callback(TEST_TOOL2, E.LINE, recorder2)
+            sys.monitoring.set_events(TEST_TOOL, E.LINE); sys.monitoring.set_events(TEST_TOOL2, E.LINE)
+            f1()
+            sys.monitoring.set_events(TEST_TOOL, 0); sys.monitoring.set_events(TEST_TOOL2, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, None)
+            sys.monitoring.register_callback(TEST_TOOL2, E.LINE, None)
+            start = LineMonitoringTest.test_lines_two.__code__.co_firstlineno
+            expected = [start+10, 14, start+11]
+            self.assertEqual(events, expected)
+            self.assertEqual(events2, expected)
+        finally:
+            sys.monitoring.set_events(TEST_TOOL, 0)
+            sys.monitoring.set_events(TEST_TOOL2, 0)
+            sys.monitoring.register_callback(TEST_TOOL, E.LINE, None)
+            sys.monitoring.register_callback(TEST_TOOL2, E.LINE, None)
+            self.assertEqual(sys.monitoring._all_events(), {})
+            sys.monitoring.restart_events()
+
+    def check_lines(self, func, expected, tool=TEST_TOOL):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            events = []
+            recorder = RecorderWithDisable(events)
+            sys.monitoring.register_callback(tool, E.LINE, recorder)
+            sys.monitoring.set_events(tool, E.LINE)
+            func()
+            sys.monitoring.set_events(tool, 0)
+            sys.monitoring.register_callback(tool, E.LINE, None)
+            lines = [ line - func.__code__.co_firstlineno for line in events[1:-1] ]
+            self.assertEqual(lines, expected)
+        finally:
+            sys.monitoring.set_events(tool, 0)
+
+
+    def test_linear(self):
+
+        def func():
+            line = 1
+            line = 2
+            line = 3
+            line = 4
+            line = 5
+
+        self.check_lines(func, [1,2,3,4,5])
+
+    def test_branch(self):
+        def func():
+            if "true".startswith("t"):
+                line = 2
+                line = 3
+            else:
+                line = 5
+            line = 6
+
+        self.check_lines(func, [1,2,3,6])
+
+    def test_try_except(self):
+
+        def func1():
+            try:
+                line = 2
+                line = 3
+            except:
+                line = 5
+            line = 6
+
+        self.check_lines(func1, [1,2,3,6])
+
+        def func2():
+            try:
+                line = 2
+                raise 3
+            except:
+                line = 5
+            line = 6
+
+        self.check_lines(func2, [1,2,3,4,5,6])
+
+
+class ExceptionRecorder:
+
+    event_type = E.RAISE
+
+    def __init__(self, events):
+        self.events = events
+
+    def __call__(self, code, offset, exc):
+        self.events.append(("raise", type(exc)))
+
+class CheckEvents(MonitoringTestBase, unittest.TestCase):
+
+    def check_events(self, func, expected, tool=TEST_TOOL, recorders=(ExceptionRecorder,)):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            event_list = []
+            all_events = 0
+            for recorder in recorders:
+                ev = recorder.event_type
+                sys.monitoring.register_callback(tool, ev, recorder(event_list))
+                all_events |= ev
+            sys.monitoring.set_events(tool, all_events)
+            func()
+            sys.monitoring.set_events(tool, 0)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, None)
+            self.assertEqual(event_list, expected)
+        finally:
+            sys.monitoring.set_events(tool, 0)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, None)
+
+class StopiterationRecorder(ExceptionRecorder):
+
+    event_type = E.STOP_ITERATION
+
+class ExceptionMontoringTest(CheckEvents):
+
+    recorder = ExceptionRecorder
+
+    def test_simple_try_except(self):
+
+        def func1():
+            try:
+                line = 2
+                raise KeyError
+            except:
+                line = 5
+            line = 6
+
+        self.check_events(func1, [("raise", KeyError)])
+
+        def gen():
+            yield 1
+            return 2
+
+        def implicit_stop_iteration():
+            for _ in gen():
+                pass
+
+        self.check_events(implicit_stop_iteration, [("raise", StopIteration)], recorders=(StopiterationRecorder,))
+
+class LineRecorder:
+
+    event_type = E.LINE
+
+
+    def __init__(self, events):
+        self.events = events
+
+    def __call__(self, code, line):
+        self.events.append(("line", code.co_name, line - code.co_firstlineno))
+
+class CallRecorder:
+
+    event_type = E.CALL
+
+    def __init__(self, events):
+        self.events = events
+
+    def __call__(self, code, offset, func, arg):
+        self.events.append(("call", func.__name__, arg))
+
+class CEventRecorder:
+
+    def __init__(self, events):
+        self.events = events
+
+    def __call__(self, code, offset, func, arg):
+        self.events.append((self.event_name, func.__name__, arg))
+
+class CReturnRecorder(CEventRecorder):
+
+    event_type = E.C_RETURN
+    event_name = "C return"
+
+class CRaiseRecorder(CEventRecorder):
+
+    event_type = E.C_RAISE
+    event_name = "C raise"
+
+MANY_RECORDERS = ExceptionRecorder, CallRecorder, LineRecorder, CReturnRecorder, CRaiseRecorder
+
+class TestManyEvents(CheckEvents):
+
+    def test_simple(self):
+
+        def func1():
+            line1 = 1
+            line2 = 2
+            line3 = 3
+
+        self.check_events(func1, recorders = MANY_RECORDERS, expected = [
+            ('line', 'check_events', 10),
+            ('call', 'func1', sys.monitoring.MISSING),
+            ('line', 'func1', 1),
+            ('line', 'func1', 2),
+            ('line', 'func1', 3),
+            ('line', 'check_events', 11),
+            ('call', 'set_events', 2)])
+
+    def test_c_call(self):
+
+        def func2():
+            line1 = 1
+            [].append(2)
+            line3 = 3
+
+        self.check_events(func2, recorders = MANY_RECORDERS, expected = [
+            ('line', 'check_events', 10),
+            ('call', 'func2', sys.monitoring.MISSING),
+            ('line', 'func2', 1),
+            ('line', 'func2', 2),
+            ('call', 'append', [2]),
+            ('C return', 'append', [2]),
+            ('line', 'func2', 3),
+            ('line', 'check_events', 11),
+            ('call', 'set_events', 2)])
+
+    def test_try_except(self):
+
+        def func3():
+            try:
+                line = 2
+                raise KeyError
+            except:
+                line = 5
+            line = 6
+
+        self.check_events(func3, recorders = MANY_RECORDERS, expected = [
+            ('line', 'check_events', 10),
+            ('call', 'func3', sys.monitoring.MISSING),
+            ('line', 'func3', 1),
+            ('line', 'func3', 2),
+            ('line', 'func3', 3),
+            ('raise', KeyError),
+            ('line', 'func3', 4),
+            ('line', 'func3', 5),
+            ('line', 'func3', 6),
+            ('line', 'check_events', 11),
+            ('call', 'set_events', 2)])
+
+class InstructionRecorder:
+
+    event_type = E.INSTRUCTION
+
+    def __init__(self, events):
+        self.events = events
+
+    def __call__(self, code, offset):
+        # Filter out instructions in check_events to lower noise
+        if code.co_name != "check_events":
+            self.events.append(("instruction", code.co_name, offset))
+
+
+LINE_AND_INSTRUCTION_RECORDERS = InstructionRecorder, LineRecorder
+
+class TestLineAndInstructionEvents(CheckEvents):
+    maxDiff = None
+
+    def test_simple(self):
+
+        def func1():
+            line1 = 1
+            line2 = 2
+            line3 = 3
+
+        self.check_events(func1, recorders = LINE_AND_INSTRUCTION_RECORDERS, expected = [
+            ('line', 'check_events', 10),
+            ('line', 'func1', 1),
+            ('instruction', 'func1', 2),
+            ('instruction', 'func1', 4),
+            ('line', 'func1', 2),
+            ('instruction', 'func1', 6),
+            ('instruction', 'func1', 8),
+            ('line', 'func1', 3),
+            ('instruction', 'func1', 10),
+            ('instruction', 'func1', 12),
+            ('instruction', 'func1', 14),
+            ('line', 'check_events', 11)])
+
+    def test_c_call(self):
+
+        def func2():
+            line1 = 1
+            [].append(2)
+            line3 = 3
+
+        self.check_events(func2, recorders = LINE_AND_INSTRUCTION_RECORDERS, expected = [
+            ('line', 'check_events', 10),
+            ('line', 'func2', 1),
+            ('instruction', 'func2', 2),
+            ('instruction', 'func2', 4),
+            ('line', 'func2', 2),
+            ('instruction', 'func2', 6),
+            ('instruction', 'func2', 8),
+            ('instruction', 'func2', 28),
+            ('instruction', 'func2', 30),
+            ('instruction', 'func2', 38),
+            ('line', 'func2', 3),
+            ('instruction', 'func2', 40),
+            ('instruction', 'func2', 42),
+            ('instruction', 'func2', 44),
+            ('line', 'check_events', 11)])
+
+    def test_try_except(self):
+
+        def func3():
+            try:
+                line = 2
+                raise KeyError
+            except:
+                line = 5
+            line = 6
+
+        self.check_events(func3, recorders = LINE_AND_INSTRUCTION_RECORDERS, expected = [
+            ('line', 'check_events', 10),
+            ('line', 'func3', 1),
+            ('instruction', 'func3', 2),
+            ('line', 'func3', 2),
+            ('instruction', 'func3', 4),
+            ('instruction', 'func3', 6),
+            ('line', 'func3', 3),
+            ('instruction', 'func3', 8),
+            ('instruction', 'func3', 18),
+            ('instruction', 'func3', 20),
+            ('line', 'func3', 4),
+            ('instruction', 'func3', 22),
+            ('line', 'func3', 5),
+            ('instruction', 'func3', 24),
+            ('instruction', 'func3', 26),
+            ('instruction', 'func3', 28),
+            ('line', 'func3', 6),
+            ('instruction', 'func3', 30),
+            ('instruction', 'func3', 32),
+            ('instruction', 'func3', 34),
+            ('line', 'check_events', 11)])
+
+class TestInstallIncrementallly(MonitoringTestBase, unittest.TestCase):
+
+    def check_events(self, func, must_include, tool=TEST_TOOL, recorders=(ExceptionRecorder,)):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            event_list = []
+            all_events = 0
+            for recorder in recorders:
+                all_events |= recorder.event_type
+                sys.monitoring.set_events(tool, all_events)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, recorder(event_list))
+            func()
+            sys.monitoring.set_events(tool, 0)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, None)
+            for line in must_include:
+                self.assertIn(line, event_list)
+        finally:
+            sys.monitoring.set_events(tool, 0)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, None)
+
+    @staticmethod
+    def func1():
+        line1 = 1
+
+    MUST_INCLUDE_LI = [
+            ('instruction', 'func1', 2),
+            ('line', 'func1', 1),
+            ('instruction', 'func1', 4),
+            ('instruction', 'func1', 6)]
+
+    def test_line_then_instruction(self):
+        recorders = [ LineRecorder, InstructionRecorder ]
+        self.check_events(self.func1,
+                          recorders = recorders, must_include = self.EXPECTED_LI)
+
+    def test_instruction_then_line(self):
+        recorders = [ InstructionRecorder, LineRecorderLowNoise ]
+        self.check_events(self.func1,
+                          recorders = recorders, must_include = self.EXPECTED_LI)
+
+    @staticmethod
+    def func2():
+        len(())
+
+    MUST_INCLUDE_CI = [
+            ('instruction', 'func2', 2),
+            ('call', 'func2', sys.monitoring.MISSING),
+            ('call', 'len', ()),
+            ('instruction', 'func2', 12),
+            ('instruction', 'func2', 14)]
+
+
+
+    def test_line_then_instruction(self):
+        recorders = [ CallRecorder, InstructionRecorder ]
+        self.check_events(self.func2,
+                          recorders = recorders, must_include = self.MUST_INCLUDE_CI)
+
+    def test_instruction_then_line(self):
+        recorders = [ InstructionRecorder, CallRecorder ]
+        self.check_events(self.func2,
+                          recorders = recorders, must_include = self.MUST_INCLUDE_CI)
+
+class TestLocalEvents(MonitoringTestBase, unittest.TestCase):
+
+    def check_events(self, func, expected, tool=TEST_TOOL, recorders=(ExceptionRecorder,)):
+        try:
+            self.assertEqual(sys.monitoring._all_events(), {})
+            event_list = []
+            all_events = 0
+            for recorder in recorders:
+                ev = recorder.event_type
+                sys.monitoring.register_callback(tool, ev, recorder(event_list))
+                all_events |= ev
+            sys.monitoring.set_local_events(tool, func.__code__, all_events)
+            func()
+            sys.monitoring.set_local_events(tool, func.__code__, 0)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, None)
+            self.assertEqual(event_list, expected)
+        finally:
+            sys.monitoring.set_local_events(tool, func.__code__, 0)
+            for recorder in recorders:
+                sys.monitoring.register_callback(tool, recorder.event_type, None)
+
+
+    def test_simple(self):
+
+        def func1():
+            line1 = 1
+            line2 = 2
+            line3 = 3
+
+        self.check_events(func1, recorders = MANY_RECORDERS, expected = [
+            ('line', 'func1', 1),
+            ('line', 'func1', 2),
+            ('line', 'func1', 3)])
+
+    def test_c_call(self):
+
+        def func2():
+            line1 = 1
+            [].append(2)
+            line3 = 3
+
+        self.check_events(func2, recorders = MANY_RECORDERS, expected = [
+            ('line', 'func2', 1),
+            ('line', 'func2', 2),
+            ('call', 'append', [2]),
+            ('C return', 'append', [2]),
+            ('line', 'func2', 3)])
+
+    def test_try_except(self):
+
+        def func3():
+            try:
+                line = 2
+                raise KeyError
+            except:
+                line = 5
+            line = 6
+
+        self.check_events(func3, recorders = MANY_RECORDERS, expected = [
+            ('line', 'func3', 1),
+            ('line', 'func3', 2),
+            ('line', 'func3', 3),
+            ('raise', KeyError),
+            ('line', 'func3', 4),
+            ('line', 'func3', 5),
+            ('line', 'func3', 6)])
+
+
+class TestSetGetEvents(MonitoringTestBase, unittest.TestCase):
+
+    def test_global(self):
+        sys.monitoring.set_events(TEST_TOOL, E.PY_START)
+        self.assertEqual(sys.monitoring.get_events(TEST_TOOL), E.PY_START)
+        sys.monitoring.set_events(TEST_TOOL2, E.PY_START)
+        self.assertEqual(sys.monitoring.get_events(TEST_TOOL2), E.PY_START)
+        sys.monitoring.set_events(TEST_TOOL, 0)
+        self.assertEqual(sys.monitoring.get_events(TEST_TOOL), 0)
+        sys.monitoring.set_events(TEST_TOOL2,0)
+        self.assertEqual(sys.monitoring.get_events(TEST_TOOL2), 0)
+
+    def test_local(self):
+        code = f1.__code__
+        sys.monitoring.set_local_events(TEST_TOOL, code, E.PY_START)
+        self.assertEqual(sys.monitoring.get_local_events(TEST_TOOL, code), E.PY_START)
+        sys.monitoring.set_local_events(TEST_TOOL2, code, E.PY_START)
+        self.assertEqual(sys.monitoring.get_local_events(TEST_TOOL2, code), E.PY_START)
+        sys.monitoring.set_local_events(TEST_TOOL, code, 0)
+        self.assertEqual(sys.monitoring.get_local_events(TEST_TOOL, code), 0)
+        sys.monitoring.set_local_events(TEST_TOOL2, code, 0)
+        self.assertEqual(sys.monitoring.get_local_events(TEST_TOOL2, code), 0)
+
+class TestUninitialized(unittest.TestCase, MonitoringTestBase):
+
+    @staticmethod
+    def f():
+        pass
+
+    def test_get_local_events_uninitialized(self):
+        self.assertEqual(sys.monitoring.get_local_events(TEST_TOOL, self.f.__code__), 0)
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1445,7 +1445,7 @@ class C(object): pass
         def func():
             return sys._getframe()
         x = func()
-        check(x, size('3Pi3c7P2ic??2P'))
+        check(x, size('3Pii3c7P2ic??2P'))
         # function
         def func(): pass
         check(func, size('14Pi'))
diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -2808,5 +2808,65 @@ def foo(*args):
         sys.settrace(sys.gettrace())
 
 
+class TestLinesAfterTraceStarted(TraceTestCase):
+
+    def test_events(self):
+        tracer = Tracer()
+        sys._getframe().f_trace = tracer.trace
+        sys.settrace(tracer.trace)
+        line = 4
+        line = 5
+        sys.settrace(None)
+        self.compare_events(
+            TestLinesAfterTraceStarted.test_events.__code__.co_firstlineno,
+            tracer.events, [
+                (4, 'line'),
+                (5, 'line'),
+                (6, 'line')])
+
+
+class TestSetLocalTrace(TraceTestCase):
+
+    def test_with_branches(self):
+
+        def tracefunc(frame, event, arg):
+            if frame.f_code.co_name == "func":
+                frame.f_trace = tracefunc
+                line = frame.f_lineno - frame.f_code.co_firstlineno
+                events.append((line, event))
+            return tracefunc
+
+        def func(arg = 1):
+            N = 1
+            if arg >= 2:
+                not_reached = 3
+            else:
+                reached = 5
+            if arg >= 3:
+                not_reached = 7
+            else:
+                reached = 9
+            the_end = 10
+
+        EXPECTED_EVENTS = [
+            (0, 'call'),
+            (1, 'line'),
+            (2, 'line'),
+            (5, 'line'),
+            (6, 'line'),
+            (9, 'line'),
+            (10, 'line'),
+            (10, 'return'),
+        ]
+
+        events = []
+        sys.settrace(tracefunc)
+        sys._getframe().f_trace = tracefunc
+        func()
+        self.assertEqual(events, EXPECTED_EVENTS)
+        sys.settrace(None)
+
+
+
 if __name__ == "__main__":
     unittest.main()