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bpo-40453: Add PyConfig._isolated_subinterpreter (GH-19820)
An isolated subinterpreter cannot spawn threads, spawn a child process or call os.fork(). * Add private _Py_NewInterpreter(isolated_subinterpreter) function. * Add isolated=True keyword-only parameter to _xxsubinterpreters.create(). * Allow again os.fork() in "non-isolated" subinterpreters.
1 parent 8bcfd31 commit 252346a

14 files changed

Lines changed: 68 additions & 12 deletions

‎Doc/c-api/init_config.rst‎

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@@ -1004,6 +1004,8 @@ Private provisional API:
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* :c:member:`PyConfig._init_main`: if set to 0,
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:c:func:`Py_InitializeFromConfig` stops at the "Core" initialization phase.
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* :c:member:`PyConfig._isolated_interpreter`: if non-zero,
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disallow threads, subprocesses and fork.
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.. c:function:: PyStatus _Py_InitializeMain(void)
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‎Include/cpython/initconfig.h‎

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@@ -409,6 +409,10 @@ typedef struct {
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/* If equal to 0, stop Python initialization before the "main" phase */
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int _init_main;
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/* If non-zero, disallow threads, subprocesses, and fork.
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Default: 0. */
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int _isolated_interpreter;
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} PyConfig;
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PyAPI_FUNC(void) PyConfig_InitPythonConfig(PyConfig *config);

‎Include/cpython/pylifecycle.h‎

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@@ -65,6 +65,8 @@ PyAPI_FUNC(int) _Py_CoerceLegacyLocale(int warn);
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PyAPI_FUNC(int) _Py_LegacyLocaleDetected(int warn);
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PyAPI_FUNC(char *) _Py_SetLocaleFromEnv(int category);
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PyAPI_FUNC(PyThreadState *) _Py_NewInterpreter(int isolated_subinterpreter);
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#ifdef __cplusplus
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}
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#endif

‎Lib/test/test__xxsubinterpreters.py‎

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@@ -794,6 +794,7 @@ def f():
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self.assertEqual(out, 'it worked!')
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def test_create_thread(self):
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subinterp = interpreters.create(isolated=False)
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script, file = _captured_script("""
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import threading
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def f():
@@ -804,7 +805,7 @@ def f():
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t.join()
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""")
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with file:
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interpreters.run_string(self.id, script)
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interpreters.run_string(subinterp, script)
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out = file.read()
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self.assertEqual(out, 'it worked!')

‎Lib/test/test_embed.py‎

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@@ -406,6 +406,7 @@ class InitConfigTests(EmbeddingTestsMixin, unittest.TestCase):
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'check_hash_pycs_mode': 'default',
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'pathconfig_warnings': 1,
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'_init_main': 1,
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'_isolated_interpreter': 0,
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}
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if MS_WINDOWS:
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CONFIG_COMPAT.update({
@@ -766,6 +767,8 @@ def test_init_from_config(self):
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'check_hash_pycs_mode': 'always',
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'pathconfig_warnings': 0,
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'_isolated_interpreter': 1,
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}
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self.check_all_configs("test_init_from_config", config, preconfig,
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api=API_COMPAT)

‎Misc/NEWS.d/next/Library/2020-04-30-22-04-58.bpo-40453.ggz7sl.rst‎

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@@ -0,0 +1,3 @@
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Add ``isolated=True`` keyword-only parameter to
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``_xxsubinterpreters.create()``. An isolated subinterpreter cannot spawn
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threads, spawn a child process or call ``os.fork()``.

‎Modules/_posixsubprocess.c‎

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@@ -663,6 +663,14 @@ subprocess_fork_exec(PyObject* self, PyObject *args)
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return NULL;
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}
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PyInterpreterState *interp = PyInterpreterState_Get();
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const PyConfig *config = _PyInterpreterState_GetConfig(interp);
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if (config->_isolated_interpreter) {
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PyErr_SetString(PyExc_RuntimeError,
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"subprocess not supported for isolated subinterpreters");
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return NULL;
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}
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/* We need to call gc.disable() when we'll be calling preexec_fn */
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if (preexec_fn != Py_None) {
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PyObject *result;

‎Modules/_threadmodule.c‎

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@@ -1085,6 +1085,14 @@ thread_PyThread_start_new_thread(PyObject *self, PyObject *fargs)
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"optional 3rd arg must be a dictionary");
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return NULL;
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}
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PyInterpreterState *interp = _PyInterpreterState_GET();
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if (interp->config._isolated_interpreter) {
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PyErr_SetString(PyExc_RuntimeError,
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"thread is not supported for isolated subinterpreters");
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return NULL;
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}
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boot = PyMem_NEW(struct bootstate, 1);
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if (boot == NULL)
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return PyErr_NoMemory();

‎Modules/_winapi.c‎

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@@ -1080,6 +1080,14 @@ _winapi_CreateProcess_impl(PyObject *module,
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return NULL;
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}
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PyInterpreterState *interp = PyInterpreterState_Get();
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const PyConfig *config = _PyInterpreterState_GetConfig(interp);
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if (config->_isolated_interpreter) {
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PyErr_SetString(PyExc_RuntimeError,
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"subprocess not supported for isolated subinterpreters");
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return NULL;
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}
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ZeroMemory(&si, sizeof(si));
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si.StartupInfo.cb = sizeof(si);
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‎Modules/_xxsubinterpretersmodule.c‎

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@@ -1999,16 +1999,20 @@ _global_channels(void) {
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}
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static PyObject *
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interp_create(PyObject *self, PyObject *args)
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interp_create(PyObject *self, PyObject *args, PyObject *kwds)
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{
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if (!PyArg_UnpackTuple(args, "create", 0, 0)) {
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static char *kwlist[] = {"isolated", NULL};
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int isolated = 1;
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "|$i:create", kwlist,
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&isolated)) {
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return NULL;
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}
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// Create and initialize the new interpreter.
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PyThreadState *save_tstate = PyThreadState_Swap(NULL);
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// XXX Possible GILState issues?
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PyThreadState *tstate = Py_NewInterpreter();
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PyThreadState *tstate = _Py_NewInterpreter(isolated);
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PyThreadState_Swap(save_tstate);
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if (tstate == NULL) {
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/* Since no new thread state was created, there is no exception to
@@ -2547,8 +2551,8 @@ channel__channel_id(PyObject *self, PyObject *args, PyObject *kwds)
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}
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static PyMethodDef module_functions[] = {
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{"create", (PyCFunction)interp_create,
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METH_VARARGS, create_doc},
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{"create", (PyCFunction)(void(*)(void))interp_create,
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METH_VARARGS | METH_KEYWORDS, create_doc},
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{"destroy", (PyCFunction)(void(*)(void))interp_destroy,
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METH_VARARGS | METH_KEYWORDS, destroy_doc},
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{"list_all", interp_list_all,

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