Revert "[3.15] gh-158552: Wait for Windows threads to suspend before blocking sampling (GH-158802) (#158845)"

This reverts commit 31288da.

Author: pablogsal

Lib/test/test_profiling/test_sampling_profiler/test_blocking.py

@@ -5,7 +5,6 @@
 import subprocess
 import sys
 import textwrap
-import time
 import unittest
 from unittest import mock
 
@@ -214,59 +213,3 @@ def test_run_blocking_exits_after_target_process_exits(self):
                 replay.returncode, 0,
                 f"stdout:\n{replay.stdout}\nstderr:\n{replay.stderr}",
             )
-
-
-@requires_remote_subprocess_debugging()
-@unittest.skipUnless(sys.platform == "win32", "Windows only")
-class TestBlockingModeSuspension(unittest.TestCase):
-    def test_all_threads_stop_before_pause_returns(self):
-        import mmap
-
-        tag = f"cpython_blocking_{os.getpid()}_{id(self)}"
-        script = textwrap.dedent(f'''
-            import mmap
-            import struct
-            import threading
-
-            memory = mmap.mmap(-1, 16, tagname={tag!r})
-
-            def worker(offset):
-                counter = 0
-                while True:
-                    counter += 1
-                    struct.pack_into("q", memory, offset, counter)
-
-            for offset in (0, 8):
-                threading.Thread(target=worker, args=(offset,), daemon=True).start()
-            _test_sock.sendall(b"working")
-            _test_sock.recv(1)
-        ''')
-        with mmap.mmap(-1, 16, tagname=tag) as memory:
-            with test_subprocess(script, wait_for_working=True) as subproc:
-                unwinder = _remote_debugging.RemoteUnwinder(
-                    subproc.process.pid, all_threads=True)
-                deadline = time.monotonic() + SHORT_TIMEOUT
-                while not all(memory[offset:offset + 8] != bytes(8)
-                              for offset in (0, 8)):
-                    self.assertLess(time.monotonic(), deadline,
-                                    "Worker threads did not start")
-                    time.sleep(0.001)
-                for _ in range(100):
-                    self.assertTrue(unwinder.pause_threads())
-                    try:
-                        before = memory[:]
-                        self.assertFalse(unwinder.pause_threads())
-                        unwinder.get_stack_trace()
-                        time.sleep(0.001)
-                        self.assertEqual(memory[:], before,
-                                         "Target memory changed while paused")
-                    finally:
-                        unwinder.resume_threads()
-                    self.assertFalse(unwinder.resume_threads())
-                before = memory[:]
-                deadline = time.monotonic() + SHORT_TIMEOUT
-                while any(memory[offset:offset + 8] == before[offset:offset + 8]
-                          for offset in (0, 8)):
-                    self.assertLess(time.monotonic(), deadline,
-                                    "Worker threads did not resume")
-                    time.sleep(0.001)

Misc/NEWS.d/next/Library/2026-10-04-20-00-00.gh-issue-158552.windows.rst

@@ -105,7 +105,6 @@ typedef struct {
 #ifdef MS_WINDOWS
 #define STATUS_SUCCESS                   ((NTSTATUS)0x00000000L)
 #define STATUS_INFO_LENGTH_MISMATCH      ((NTSTATUS)0xC0000004L)
-#define STATUS_NO_MORE_ENTRIES           ((NTSTATUS)0x8000001AL)
 typedef enum _WIN32_THREADSTATE {
     WIN32_THREADSTATE_INITIALIZED = 0,
     WIN32_THREADSTATE_READY       = 1,

Modules/_remote_debugging/_remote_debugging.h

@@ -828,89 +828,6 @@ _Py_RemoteDebug_ResumeAllThreads(RemoteUnwinderObject *unwinder, _Py_RemoteDebug
 
 #elif defined(MS_WINDOWS)
 
-static int
-wait_for_threads_to_stop(RemoteUnwinderObject *unwinder)
-{
-    typedef NTSTATUS (NTAPI *NtGetNextThreadFunc)(
-        HANDLE, HANDLE, ACCESS_MASK, ULONG, ULONG, PHANDLE);
-    static NtGetNextThreadFunc pNtGetNextThread = NULL;
-    static int tried_load = 0;
-
-    if (!tried_load) {
-        HMODULE hNtdll = GetModuleHandleW(L"ntdll.dll");
-        if (hNtdll) {
-            pNtGetNextThread = (NtGetNextThreadFunc)GetProcAddress(
-                hNtdll, "NtGetNextThread");
-        }
-        tried_load = 1;
-    }
-    if (pNtGetNextThread == NULL) {
-        PyErr_SetString(PyExc_RuntimeError, "NtGetNextThread not available");
-        return -1;
-    }
-
-    HANDLE previous = NULL;
-    int result = -1;
-    for (;;) {
-        HANDLE next = NULL;
-        // Enumerate with the available access, then obtain context access
-        // separately so threads that deny it are not silently skipped.
-        NTSTATUS status = pNtGetNextThread(unwinder->handle.hProcess,
-                                           previous, MAXIMUM_ALLOWED, 0, 0, &next);
-        if (previous != NULL) {
-            CloseHandle(previous);
-        }
-        previous = next;
-        if (status == STATUS_NO_MORE_ENTRIES) {
-            break;
-        }
-        if (status < 0) {
-            if (!is_process_alive(unwinder->handle.hProcess)) {
-                PyErr_Format(PyExc_ProcessLookupError,
-                             "Process %d has terminated", unwinder->handle.pid);
-            }
-            else {
-                PyErr_Format(PyExc_RuntimeError,
-                             "NtGetNextThread failed: 0x%lx", status);
-            }
-            goto done;
-        }
-        HANDLE thread;
-        if (!DuplicateHandle(GetCurrentProcess(), next, GetCurrentProcess(),
-                             &thread, THREAD_GET_CONTEXT | SYNCHRONIZE,
-                             FALSE, 0)) {
-            PyErr_SetFromWindowsErr(GetLastError());
-            goto done;
-        }
-        // Suspension is asynchronous. Reading the context waits for the
-        // thread to stop before we start reading the target's memory.
-        CONTEXT context = {.ContextFlags = CONTEXT_CONTROL};
-        if (!GetThreadContext(thread, &context)) {
-            DWORD error = GetLastError();
-            int exited = WaitForSingleObject(thread, 0) == WAIT_OBJECT_0;
-            CloseHandle(thread);
-            if (exited) {
-                continue;
-            }
-            PyErr_SetFromWindowsErr(error);
-            goto done;
-        }
-        CloseHandle(thread);
-    }
-    if (!is_process_alive(unwinder->handle.hProcess)) {
-        PyErr_Format(PyExc_ProcessLookupError,
-                     "Process %d has terminated", unwinder->handle.pid);
-        goto done;
-    }
-    result = 0;
-
-done:
-    if (previous != NULL) {
-        CloseHandle(previous);
-    }
-    return result;
-}
-
 void
 _Py_RemoteDebug_InitThreadsState(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_ThreadsState *st)
 {
@@ -941,12 +858,6 @@ _Py_RemoteDebug_StopAllThreads(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_T
     if (status >= 0) {
         st->hProcess = unwinder->handle.hProcess;
         st->suspended = 1;
-        if (wait_for_threads_to_stop(unwinder) < 0) {
-            // pause_threads() has not yet set threads_stopped, so its caller
-            // will not resume the process when we return an error.
-            _Py_RemoteDebug_ResumeAllThreads(unwinder, st);
-            return -1;
-        }
         _Py_RemoteDebug_ClearCache(&unwinder->handle);
         return 0;
     }