Revert "[3.15] gh-153364: Make frame, coroutine, and task-waiter chain walks iterative and bounded (GH-153365) (#158813)"

This reverts commit 9e401cf.

Author: pablogsal

Lib/test/test_external_inspection.py

@@ -340,40 +340,6 @@ def _run_script_and_get_trace(
             finally:
                 _cleanup_sockets(client_socket, server_socket)
 
-    @contextmanager
-    def _target_process(self, script_body):
-        """Context manager for running a target process with socket sync."""
-        port = find_unused_port()
-        script = f"""\
-import socket
-sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-sock.connect(('localhost', {port}))
-{textwrap.dedent(script_body)}
-"""
-
-        with os_helper.temp_dir() as work_dir:
-            script_dir = os.path.join(work_dir, "script_pkg")
-            os.mkdir(script_dir)
-
-            server_socket = _create_server_socket(port)
-            script_name = _make_test_script(script_dir, "script", script)
-            client_socket = None
-
-            try:
-                with _managed_subprocess([sys.executable, script_name]) as p:
-                    client_socket, _ = server_socket.accept()
-                    server_socket.close()
-                    server_socket = None
-
-                    def make_unwinder(cache_frames=True):
-                        return RemoteUnwinder(
-                            p.pid, all_threads=True, cache_frames=cache_frames
-                        )
-
-                    yield p, client_socket, make_unwinder
-            finally:
-                _cleanup_sockets(client_socket, server_socket)
-
     def _find_frame_in_trace(self, stack_trace, predicate):
         """
         Find a frame matching predicate in stack trace.
@@ -1539,71 +1505,6 @@ def matches_awaited_by_pattern(task):
             finally:
                 _cleanup_sockets(client_socket, server_socket)
 
-    @skip_if_not_supported
-    @unittest.skipIf(
-        sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
-        "Test only runs on Linux with process_vm_readv support",
-    )
-    def test_async_awaited_by_skips_set_tombstones(self):
-        script_body = """\
-            import asyncio
-
-            class RemovedTask(asyncio.Task):
-                def __hash__(self):
-                    return 0
-
-            class RemainingTask(asyncio.Task):
-                def __hash__(self):
-                    return 1
-
-            async def main():
-                victim = asyncio.current_task()
-                victim.set_name("victim")
-                removed = RemovedTask(
-                    asyncio.sleep(10_000), name="removed"
-                )
-                remaining = RemainingTask(
-                    asyncio.sleep(10_000), name="remaining"
-                )
-
-                asyncio.future_add_to_awaited_by(victim, removed)
-                asyncio.future_add_to_awaited_by(victim, remaining)
-
-                # Removing hash 0 leaves a dummy in slot 0 before the only
-                # active entry in slot 1. It must not count toward the set's
-                # used entries.
-                asyncio.future_discard_from_awaited_by(victim, removed)
-
-                sock.sendall(b"ready")
-                sock.recv(16)
-
-            asyncio.run(main())
-            """
-
-        with self._target_process(script_body) as (
-            _,
-            client_socket,
-            make_unwinder,
-        ):
-            _wait_for_signal(client_socket, b"ready")
-
-            for method_name in (
-                "get_async_stack_trace",
-                "get_all_awaited_by",
-            ):
-                with self.subTest(method=method_name):
-                    unwinder = make_unwinder(cache_frames=False)
-                    stack_trace = getattr(unwinder, method_name)()
-                    relationships = self._get_awaited_by_relationships(
-                        stack_trace
-                    )
-                    self.assertEqual(
-                        relationships["victim"],
-                        {"remaining"},
-                    )
-
-            client_socket.sendall(b"done")
-
     @skip_if_not_supported
     @unittest.skipIf(
         sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
@@ -3215,6 +3116,40 @@ class TestFrameCaching(RemoteInspectionTestBase):
     All tests verify cache reuse via object identity checks (assertIs).
     """
 
+    @contextmanager
+    def _target_process(self, script_body):
+        """Context manager for running a target process with socket sync."""
+        port = find_unused_port()
+        script = f"""\
+import socket
+sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+sock.connect(('localhost', {port}))
+{textwrap.dedent(script_body)}
+"""
+
+        with os_helper.temp_dir() as work_dir:
+            script_dir = os.path.join(work_dir, "script_pkg")
+            os.mkdir(script_dir)
+
+            server_socket = _create_server_socket(port)
+            script_name = _make_test_script(script_dir, "script", script)
+            client_socket = None
+
+            try:
+                with _managed_subprocess([sys.executable, script_name]) as p:
+                    client_socket, _ = server_socket.accept()
+                    server_socket.close()
+                    server_socket = None
+
+                    def make_unwinder(cache_frames=True):
+                        return RemoteUnwinder(
+                            p.pid, all_threads=True, cache_frames=cache_frames
+                        )
+
+                    yield p, client_socket, make_unwinder
+            finally:
+                _cleanup_sockets(client_socket, server_socket)
+
     def _get_frames_with_retry(self, unwinder, required_funcs):
         """Get frames containing required_funcs, with retry for transient errors."""
         for _ in range(MAX_TRIES):
@@ -4058,163 +3993,5 @@ def test_get_stats_disabled_raises(self):
             client_socket.sendall(b"done")
 
 
-@requires_remote_subprocess_debugging()
-class TestFrameChainLimits(RemoteInspectionTestBase):
-    """Frame chain walks abort instead of looping/overflowing on deep chains."""
-
-    # Limits plus one, to exceed them (must match MAX_FRAME_CHAIN_DEPTH /
-    # MAX_TASK_WAITER_WALK_TASKS from _remote_debugging.h)
-    FRAME_CHAIN_DEPTH = 1024 + 512 + 1
-    TASK_WAITER_WALK_TASKS = 2**14 + 1
-
-    def _assert_unwinder_limit_error(self, unwind, expected_substring):
-        """Call unwind() until it raises the frame chain limit error.
-
-        unwind must construct the RemoteUnwinder and call it, so that
-        transient RuntimeErrors from either step are retried; a successful
-        call means the limit never triggered and fails immediately.
-        """
-        last_error = None
-        for _ in busy_retry(SHORT_TIMEOUT, error=False):
-            try:
-                unwind()
-            except TRANSIENT_ERRORS as e:
-                if expected_substring in str(e):
-                    return
-                last_error = e
-                continue
-            self.fail(
-                "frame chain limit did not trigger; call returned a result"
-            )
-        self.fail(
-            f"frame chain limit never raised; last transient error: "
-            f"{last_error!r}"
-        )
-
-    @skip_if_not_supported
-    @unittest.skipIf(
-        sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
-        "Test only runs on Linux with process_vm_readv support",
-    )
-    def test_get_stack_trace_deep_frame_chain_aborts(self):
-        """Test that a frame chain deeper than the limit aborts the
-        synchronous stack walk instead of walking it indefinitely."""
-        script_body = f"""\
-            import sys
-            sys.setrecursionlimit({self.FRAME_CHAIN_DEPTH * 2})
-
-            def recurse(n):
-                if n <= 0:
-                    sock.sendall(b"ready")
-                    sock.recv(16)
-                    return
-                recurse(n - 1)
-
-            recurse({self.FRAME_CHAIN_DEPTH})
-            """
-        with self._target_process(script_body) as (p, client_socket, _):
-            _wait_for_signal(client_socket, b"ready")
-            self._assert_unwinder_limit_error(
-                lambda: RemoteUnwinder(p.pid).get_stack_trace(),
-                "Too many stack frames",
-            )
-            client_socket.sendall(b"done")
-
-    @skip_if_not_supported
-    @unittest.skipIf(
-        sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
-        "Test only runs on Linux with process_vm_readv support",
-    )
-    def test_get_async_stack_trace_deep_task_waiter_chain_aborts(self):
-        """Test that a task waiter chain deeper than the limit aborts
-        the walk instead of overflowing the C stack."""
-        script_body = f"""\
-            import asyncio
-
-            async def chain(n):
-                if n <= 0:
-                    sock.sendall(b"ready")
-                    sock.recv(16)
-                    return
-
-                task = asyncio.create_task(chain(n - 1))
-                await task
-
-            asyncio.run(chain({self.TASK_WAITER_WALK_TASKS}))
-            """
-        with self._target_process(script_body) as (p, client_socket, _):
-            _wait_for_signal(client_socket, b"ready")
-            self._assert_unwinder_limit_error(
-                lambda: RemoteUnwinder(p.pid).get_async_stack_trace(),
-                "Too many task waiters",
-            )
-            client_socket.sendall(b"done")
-
-    @skip_if_not_supported
-    @unittest.skipIf(
-        sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
-        "Test only runs on Linux with process_vm_readv support",
-    )
-    def test_get_async_stack_trace_deep_frame_chain_aborts(self):
-        """Test that a frame chain deeper than the limit aborts the async
-        stack walk instead of walking it indefinitely."""
-        script_body = f"""\
-            import sys, asyncio
-            sys.setrecursionlimit({self.FRAME_CHAIN_DEPTH * 2})
-
-            def recurse(n):
-                if n <= 0:
-                    sock.sendall(b"ready")
-                    sock.recv(16)
-                    return
-                recurse(n - 1)
-
-            async def deep():
-                recurse({self.FRAME_CHAIN_DEPTH})
-
-            asyncio.run(deep())
-            """
-        with self._target_process(script_body) as (p, client_socket, _):
-            _wait_for_signal(client_socket, b"ready")
-            self._assert_unwinder_limit_error(
-                lambda: RemoteUnwinder(p.pid).get_async_stack_trace(),
-                "Too many async stack frames",
-            )
-            client_socket.sendall(b"done")
-
-    @skip_if_not_supported
-    @unittest.skipIf(
-        sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
-        "Test only runs on Linux with process_vm_readv support",
-    )
-    def test_get_all_awaited_by_deep_coro_chain_aborts(self):
-        """Test that a coroutine await chain deeper than the limit aborts
-        the walk instead of overflowing the C stack."""
-        script_body = f"""\
-            import sys, asyncio
-            sys.setrecursionlimit({self.FRAME_CHAIN_DEPTH * 2})
-
-            async def chain(n):
-                if n <= 0:
-                    await asyncio.sleep(10_000)
-                    return
-                await chain(n - 1)
-
-            async def main():
-                task = asyncio.create_task(chain({self.FRAME_CHAIN_DEPTH}))
-                await asyncio.sleep(0)
-                sock.sendall(b"ready")
-                await task
-
-            asyncio.run(main())
-            """
-        with self._target_process(script_body) as (p, client_socket, _):
-            _wait_for_signal(client_socket, b"ready")
-            self._assert_unwinder_limit_error(
-                lambda: RemoteUnwinder(p.pid).get_all_awaited_by(),
-                "Too many coroutine frames",
-            )
-
-
 if __name__ == "__main__":
     unittest.main()