Issue #9205: concurrent.futures.ProcessPoolExecutor now detects killed

children and raises BrokenProcessPool in such a situation.  Previously it
would reliably freeze/deadlock.

1 files changed, 374 insertions, 16 deletions

diff --git a/Modules/_multiprocessing/win32_functions.c b/Modules/_multiprocessing/win32_functions.c
index 12dc0cd8478..c017b2a6b7b 100644
--- a/Modules/_multiprocessing/win32_functions.c
+++ b/Modules/_multiprocessing/win32_functions.c
@@ -12,10 +12,223 @@
 #define WIN32_FUNCTION(func) \
     {#func, (PyCFunction)win32_ ## func, METH_VARARGS | METH_STATIC, ""}
 
+#define WIN32_KWARGS_FUNCTION(func) \
+    {#func, (PyCFunction)win32_ ## func, METH_VARARGS | METH_KEYWORDS | METH_STATIC, ""}
+
 #define WIN32_CONSTANT(fmt, con) \
     PyDict_SetItemString(Win32Type.tp_dict, #con, Py_BuildValue(fmt, con))
 
 
+/* Grab CancelIoEx dynamically from kernel32 */
+static int has_CancelIoEx = -1;
+static BOOL (CALLBACK *Py_CancelIoEx)(HANDLE, LPOVERLAPPED);
+
+static int
+check_CancelIoEx()
+{
+    if (has_CancelIoEx == -1)
+    {
+        HINSTANCE hKernel32 = GetModuleHandle("KERNEL32");
+        * (FARPROC *) &Py_CancelIoEx = GetProcAddress(hKernel32,
+                                                      "CancelIoEx");
+        has_CancelIoEx = (Py_CancelIoEx != NULL);
+    }
+    return has_CancelIoEx;
+}
+
+
+/*
+ * A Python object wrapping an OVERLAPPED structure and other useful data
+ * for overlapped I/O
+ */
+
+typedef struct {
+    PyObject_HEAD
+    OVERLAPPED overlapped;
+    /* For convenience, we store the file handle too */
+    HANDLE handle;
+    /* Whether there's I/O in flight */
+    int pending;
+    /* Whether I/O completed successfully */
+    int completed;
+    /* Buffer used for reading (optional) */
+    PyObject *read_buffer;
+    /* Buffer used for writing (optional) */
+    Py_buffer write_buffer;
+} OverlappedObject;
+
+static void
+overlapped_dealloc(OverlappedObject *self)
+{
+    int err = GetLastError();
+    if (self->pending) {
+        if (check_CancelIoEx())
+            Py_CancelIoEx(self->handle, &self->overlapped);
+        else {
+            PyErr_SetString(PyExc_RuntimeError,
+                            "I/O operations still in flight while destroying "
+                            "Overlapped object, the process may crash");
+            PyErr_WriteUnraisable(NULL);
+        }
+    }
+    CloseHandle(self->overlapped.hEvent);
+    SetLastError(err);
+    if (self->write_buffer.obj)
+        PyBuffer_Release(&self->write_buffer);
+    Py_CLEAR(self->read_buffer);
+    PyObject_Del(self);
+}
+
+static PyObject *
+overlapped_GetOverlappedResult(OverlappedObject *self, PyObject *waitobj)
+{
+    int wait;
+    BOOL res;
+    DWORD transferred = 0;
+
+    wait = PyObject_IsTrue(waitobj);
+    if (wait < 0)
+        return NULL;
+    Py_BEGIN_ALLOW_THREADS
+    res = GetOverlappedResult(self->handle, &self->overlapped, &transferred,
+                              wait != 0);
+    Py_END_ALLOW_THREADS
+
+    if (!res) {
+        int err = GetLastError();
+        if (err == ERROR_IO_INCOMPLETE)
+            Py_RETURN_NONE;
+        if (err != ERROR_MORE_DATA) {
+            self->pending = 0;
+            return PyErr_SetExcFromWindowsErr(PyExc_IOError, err);
+        }
+    }
+    self->pending = 0;
+    self->completed = 1;
+    if (self->read_buffer) {
+        assert(PyBytes_CheckExact(self->read_buffer));
+        if (_PyBytes_Resize(&self->read_buffer, transferred))
+            return NULL;
+    }
+    return Py_BuildValue("lN", (long) transferred, PyBool_FromLong(res));
+}
+
+static PyObject *
+overlapped_getbuffer(OverlappedObject *self)
+{
+    PyObject *res;
+    if (!self->completed) {
+        PyErr_SetString(PyExc_ValueError,
+                        "can't get read buffer before GetOverlappedResult() "
+                        "signals the operation completed");
+        return NULL;
+    }
+    res = self->read_buffer ? self->read_buffer : Py_None;
+    Py_INCREF(res);
+    return res;
+}
+
+static PyObject *
+overlapped_cancel(OverlappedObject *self)
+{
+    BOOL res = TRUE;
+
+    if (self->pending) {
+        Py_BEGIN_ALLOW_THREADS
+        if (check_CancelIoEx())
+            res = Py_CancelIoEx(self->handle, &self->overlapped);
+        else
+            res = CancelIo(self->handle);
+        Py_END_ALLOW_THREADS
+    }
+
+    /* CancelIoEx returns ERROR_NOT_FOUND if the I/O completed in-between */
+    if (!res && GetLastError() != ERROR_NOT_FOUND)
+        return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
+    self->pending = 0;
+    Py_RETURN_NONE;
+}
+
+static PyMethodDef overlapped_methods[] = {
+    {"GetOverlappedResult", (PyCFunction) overlapped_GetOverlappedResult,
+                            METH_O, NULL},
+    {"getbuffer", (PyCFunction) overlapped_getbuffer, METH_NOARGS, NULL},
+    {"cancel", (PyCFunction) overlapped_cancel, METH_NOARGS, NULL},
+    {NULL}
+};
+
+static PyMemberDef overlapped_members[] = {
+    {"event", T_HANDLE,
+     offsetof(OverlappedObject, overlapped) + offsetof(OVERLAPPED, hEvent),
+     READONLY, "overlapped event handle"},
+    {NULL}
+};
+
+PyTypeObject OverlappedType = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    /* tp_name           */ "_multiprocessing.win32.Overlapped",
+    /* tp_basicsize      */ sizeof(OverlappedObject),
+    /* tp_itemsize       */ 0,
+    /* tp_dealloc        */ (destructor) overlapped_dealloc,
+    /* tp_print          */ 0,
+    /* tp_getattr        */ 0,
+    /* tp_setattr        */ 0,
+    /* tp_reserved       */ 0,
+    /* tp_repr           */ 0,
+    /* tp_as_number      */ 0,
+    /* tp_as_sequence    */ 0,
+    /* tp_as_mapping     */ 0,
+    /* tp_hash           */ 0,
+    /* tp_call           */ 0,
+    /* tp_str            */ 0,
+    /* tp_getattro       */ 0,
+    /* tp_setattro       */ 0,
+    /* tp_as_buffer      */ 0,
+    /* tp_flags          */ Py_TPFLAGS_DEFAULT,
+    /* tp_doc            */ "OVERLAPPED structure wrapper",
+    /* tp_traverse       */ 0,
+    /* tp_clear          */ 0,
+    /* tp_richcompare    */ 0,
+    /* tp_weaklistoffset */ 0,
+    /* tp_iter           */ 0,
+    /* tp_iternext       */ 0,
+    /* tp_methods        */ overlapped_methods,
+    /* tp_members        */ overlapped_members,
+    /* tp_getset         */ 0,
+    /* tp_base           */ 0,
+    /* tp_dict           */ 0,
+    /* tp_descr_get      */ 0,
+    /* tp_descr_set      */ 0,
+    /* tp_dictoffset     */ 0,
+    /* tp_init           */ 0,
+    /* tp_alloc          */ 0,
+    /* tp_new            */ 0,
+};
+
+static OverlappedObject *
+new_overlapped(HANDLE handle)
+{
+    OverlappedObject *self;
+
+    self = PyObject_New(OverlappedObject, &OverlappedType);
+    if (!self)
+        return NULL;
+    self->handle = handle;
+    self->read_buffer = NULL;
+    self->pending = 0;
+    self->completed = 0;
+    memset(&self->overlapped, 0, sizeof(OVERLAPPED));
+    memset(&self->write_buffer, 0, sizeof(Py_buffer));
+    /* Manual reset, initially non-signalled */
+    self->overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+    return self;
+}
+
+
+/*
+ * Module functions
+ */
+
 static PyObject *
 win32_CloseHandle(PyObject *self, PyObject *args)
 {
@@ -36,20 +249,44 @@ win32_CloseHandle(PyObject *self, PyObject *args)
 }
 
 static PyObject *
-win32_ConnectNamedPipe(PyObject *self, PyObject *args)
+win32_ConnectNamedPipe(PyObject *self, PyObject *args, PyObject *kwds)
 {
     HANDLE hNamedPipe;
-    LPOVERLAPPED lpOverlapped;
+    int use_overlapped = 0;
     BOOL success;
+    OverlappedObject *overlapped = NULL;
+    static char *kwlist[] = {"handle", "overlapped", NULL};
 
-    if (!PyArg_ParseTuple(args, F_HANDLE F_POINTER,
-                          &hNamedPipe, &lpOverlapped))
+    if (!PyArg_ParseTupleAndKeywords(args, kwds,
+                                     F_HANDLE "|i", kwlist,
+                                     &hNamedPipe, &use_overlapped))
         return NULL;
 
+    if (use_overlapped) {
+        overlapped = new_overlapped(hNamedPipe);
+        if (!overlapped)
+            return NULL;
+    }
+
     Py_BEGIN_ALLOW_THREADS
-    success = ConnectNamedPipe(hNamedPipe, lpOverlapped);
+    success = ConnectNamedPipe(hNamedPipe,
+                               overlapped ? &overlapped->overlapped : NULL);
     Py_END_ALLOW_THREADS
 
+    if (overlapped) {
+        int err = GetLastError();
+        /* Overlapped ConnectNamedPipe never returns a success code */
+        assert(success == 0);
+        if (err == ERROR_IO_PENDING)
+            overlapped->pending = 1;
+        else if (err == ERROR_PIPE_CONNECTED)
+            SetEvent(overlapped->overlapped.hEvent);
+        else {
+            Py_DECREF(overlapped);
+            return PyErr_SetFromWindowsErr(err);
+        }
+        return (PyObject *) overlapped;
+    }
     if (!success)
         return PyErr_SetFromWindowsErr(0);
 
@@ -280,46 +517,109 @@ win32_send(PyObject *self, PyObject *args)
 }
 
 static PyObject *
-win32_WriteFile(PyObject *self, PyObject *args)
+win32_WriteFile(PyObject *self, PyObject *args, PyObject *kwds)
 {
     HANDLE handle;
-    Py_buffer buf;
+    Py_buffer _buf, *buf;
+    PyObject *bufobj;
     int written;
     BOOL ret;
+    int use_overlapped = 0;
+    OverlappedObject *overlapped = NULL;
+    static char *kwlist[] = {"handle", "buffer", "overlapped", NULL};
+
+    /* First get handle and use_overlapped to know which Py_buffer to use */
+    if (!PyArg_ParseTupleAndKeywords(args, kwds,
+                                     F_HANDLE "O|i:WriteFile", kwlist,
+                                     &handle, &bufobj, &use_overlapped))
+        return NULL;
+
+    if (use_overlapped) {
+        overlapped = new_overlapped(handle);
+        if (!overlapped)
+            return NULL;
+        buf = &overlapped->write_buffer;
+    }
+    else
+        buf = &_buf;
 
-    if (!PyArg_ParseTuple(args, F_HANDLE "y*:WriteFile" , &handle, &buf))
+    if (!PyArg_Parse(bufobj, "y*", buf)) {
+        Py_XDECREF(overlapped);
         return NULL;
+    }
 
     Py_BEGIN_ALLOW_THREADS
-    ret = WriteFile(handle, buf.buf, buf.len, &written, NULL);
+    ret = WriteFile(handle, buf->buf, buf->len, &written,
+                    overlapped ? &overlapped->overlapped : NULL);
     Py_END_ALLOW_THREADS
 
-    PyBuffer_Release(&buf);
+    if (overlapped) {
+        int err = GetLastError();
+        if (!ret) {
+            if (err == ERROR_IO_PENDING)
+                overlapped->pending = 1;
+            else {
+                Py_DECREF(overlapped);
+                return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
+            }
+        }
+        return (PyObject *) overlapped;
+    }
+
+    PyBuffer_Release(buf);
     if (!ret)
         return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
     return PyLong_FromLong(written);
 }
 
 static PyObject *
-win32_ReadFile(PyObject *self, PyObject *args)
+win32_ReadFile(PyObject *self, PyObject *args, PyObject *kwds)
 {
     HANDLE handle;
     int size;
     DWORD nread;
     PyObject *buf;
     BOOL ret;
+    int use_overlapped = 0;
+    OverlappedObject *overlapped = NULL;
+    static char *kwlist[] = {"handle", "size", "overlapped", NULL};
 
-    if (!PyArg_ParseTuple(args, F_HANDLE "i:ReadFile" , &handle, &size))
+    if (!PyArg_ParseTupleAndKeywords(args, kwds,
+                                     F_HANDLE "i|i:ReadFile", kwlist,
+                                     &handle, &size, &use_overlapped))
         return NULL;
 
     buf = PyBytes_FromStringAndSize(NULL, size);
     if (!buf)
         return NULL;
+    if (use_overlapped) {
+        overlapped = new_overlapped(handle);
+        if (!overlapped) {
+            Py_DECREF(buf);
+            return NULL;
+        }
+        /* Steals reference to buf */
+        overlapped->read_buffer = buf;
+    }
 
     Py_BEGIN_ALLOW_THREADS
-    ret = ReadFile(handle, PyBytes_AS_STRING(buf), size, &nread, NULL);
+    ret = ReadFile(handle, PyBytes_AS_STRING(buf), size, &nread,
+                   overlapped ? &overlapped->overlapped : NULL);
     Py_END_ALLOW_THREADS
 
+    if (overlapped) {
+        int err = GetLastError();
+        if (!ret) {
+            if (err == ERROR_IO_PENDING)
+                overlapped->pending = 1;
+            else if (err != ERROR_MORE_DATA) {
+                Py_DECREF(overlapped);
+                return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
+            }
+        }
+        return (PyObject *) overlapped;
+    }
+
     if (!ret && GetLastError() != ERROR_MORE_DATA) {
         Py_DECREF(buf);
         return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
@@ -373,19 +673,71 @@ win32_PeekNamedPipe(PyObject *self, PyObject *args)
     }
 }
 
+static PyObject *
+win32_WaitForMultipleObjects(PyObject* self, PyObject* args)
+{
+    DWORD result;
+    PyObject *handle_seq;
+    HANDLE handles[MAXIMUM_WAIT_OBJECTS];
+    Py_ssize_t nhandles, i;
+    int wait_flag;
+    int milliseconds = INFINITE;
+
+    if (!PyArg_ParseTuple(args, "Oi|i:WaitForMultipleObjects",
+                                &handle_seq, &wait_flag, &milliseconds))
+        return NULL;
+
+    if (!PySequence_Check(handle_seq)) {
+        PyErr_Format(PyExc_TypeError,
+                     "sequence type expected, got '%s'",
+                     Py_TYPE(handle_seq)->tp_doc);
+        return NULL;
+    }
+    nhandles = PySequence_Length(handle_seq);
+    if (nhandles == -1)
+        return NULL;
+    if (nhandles < 0 || nhandles >= MAXIMUM_WAIT_OBJECTS) {
+        PyErr_Format(PyExc_ValueError,
+                     "need at most %zd handles, got a sequence of length %zd",
+                     MAXIMUM_WAIT_OBJECTS, nhandles);
+        return NULL;
+    }
+    for (i = 0; i < nhandles; i++) {
+        HANDLE h;
+        PyObject *v = PySequence_GetItem(handle_seq, i);
+        if (v == NULL)
+            return NULL;
+        if (!PyArg_Parse(v, F_HANDLE, &h))
+            return NULL;
+        handles[i] = h;
+    }
+
+    Py_BEGIN_ALLOW_THREADS
+    result = WaitForMultipleObjects((DWORD) nhandles, handles,
+                                    (BOOL) wait_flag, (DWORD) milliseconds);
+    Py_END_ALLOW_THREADS
+
+    if (result == WAIT_FAILED)
+        return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
+
+    return PyLong_FromLong((int) result);
+}
+
+
 static PyMethodDef win32_methods[] = {
     WIN32_FUNCTION(CloseHandle),
     WIN32_FUNCTION(GetLastError),
     WIN32_FUNCTION(OpenProcess),
     WIN32_FUNCTION(ExitProcess),
-    WIN32_FUNCTION(ConnectNamedPipe),
+    WIN32_KWARGS_FUNCTION(ConnectNamedPipe),
     WIN32_FUNCTION(CreateFile),
     WIN32_FUNCTION(CreateNamedPipe),
-    WIN32_FUNCTION(ReadFile),
+    WIN32_KWARGS_FUNCTION(ReadFile),
     WIN32_FUNCTION(PeekNamedPipe),
     WIN32_FUNCTION(SetNamedPipeHandleState),
+    WIN32_FUNCTION(WaitForMultipleObjects),
     WIN32_FUNCTION(WaitNamedPipe),
-    WIN32_FUNCTION(WriteFile),
+    WIN32_KWARGS_FUNCTION(WriteFile),
     WIN32_FUNCTION(closesocket),
     WIN32_FUNCTION(recv),
     WIN32_FUNCTION(send),
@@ -407,12 +759,18 @@ create_win32_namespace(void)
         return NULL;
     Py_INCREF(&Win32Type);
 
+    if (PyType_Ready(&OverlappedType) < 0)
+        return NULL;
+    PyDict_SetItemString(Win32Type.tp_dict, "Overlapped",
+                         (PyObject *) &OverlappedType);
+
     WIN32_CONSTANT(F_DWORD, ERROR_ALREADY_EXISTS);
     WIN32_CONSTANT(F_DWORD, ERROR_BROKEN_PIPE);
     WIN32_CONSTANT(F_DWORD, ERROR_NO_SYSTEM_RESOURCES);
     WIN32_CONSTANT(F_DWORD, ERROR_PIPE_BUSY);
     WIN32_CONSTANT(F_DWORD, ERROR_PIPE_CONNECTED);
     WIN32_CONSTANT(F_DWORD, ERROR_SEM_TIMEOUT);
+    WIN32_CONSTANT(F_DWORD, FILE_FLAG_OVERLAPPED);
     WIN32_CONSTANT(F_DWORD, GENERIC_READ);
     WIN32_CONSTANT(F_DWORD, GENERIC_WRITE);
     WIN32_CONSTANT(F_DWORD, INFINITE);