Add is_running().

Author: ericsnowcurrently

Doc/library/_interpreters.rst

@@ -41,6 +41,12 @@ It defines the following functions:
    Return the ID of the currently running interpreter.
 
 
+.. function:: is_running(id)
+
+   Return whether or not the identified interpreter is currently
+   running any code.
+
+
 .. function:: create()
 
    Initialize a new Python interpreter and return its identifier.  The

Lib/test/test__interpreters.py

@@ -111,6 +111,36 @@ def test_sub(self):
         self.assertEqual(id2, id1)
 
 
+class IsRunningTests(TestBase):
+
+    def test_main_running(self):
+        main, = interpreters.enumerate()
+        sub = interpreters.create()
+        main_running = interpreters.is_running(main)
+        sub_running = interpreters.is_running(sub)
+
+        self.assertTrue(main_running)
+        self.assertFalse(sub_running)
+
+    def test_sub_running(self):
+        main, = interpreters.enumerate()
+        sub1 = interpreters.create()
+        sub2 = interpreters.create()
+        ns = interpreters.run_string_unrestricted(sub1, dedent(f"""
+            import _interpreters
+            main = _interpreters.is_running({main})
+            sub1 = _interpreters.is_running({sub1})
+            sub2 = _interpreters.is_running({sub2})
+            """))
+        main_running = ns['main']
+        sub1_running = ns['sub1']
+        sub2_running = ns['sub2']
+
+        self.assertTrue(main_running)
+        self.assertTrue(sub1_running)
+        self.assertFalse(sub2_running)
+
+
 class CreateTests(TestBase):
 
     def test_in_main(self):

Modules/_interpretersmodule.c

@@ -533,6 +533,34 @@ Return True if the object's data may be shared between interpreters and\n\
 False otherwise.");
 
 
+static PyObject *
+interp_is_running(PyObject *self, PyObject *args)
+{
+    PyObject *id;
+    if (!PyArg_UnpackTuple(args, "is_running", 1, 1, &id))
+        return NULL;
+    if (!PyLong_Check(id)) {
+        PyErr_SetString(PyExc_TypeError, "ID must be an int");
+        return NULL;
+    }
+
+    PyInterpreterState *interp = _look_up(id);
+    if (interp == NULL)
+        return NULL;
+    int is_running = _is_running(interp);
+    if (is_running < 0)
+        return NULL;
+    if (is_running)
+        Py_RETURN_TRUE;
+    Py_RETURN_FALSE;
+}
+
+PyDoc_STRVAR(is_running_doc,
+"is_running(id) -> bool\n\
+\n\
+Return whether or not the identified interpreter is running.");
+
+
 static PyMethodDef module_functions[] = {
     {"create",                  (PyCFunction)interp_create,
      METH_VARARGS, create_doc},
@@ -543,6 +571,8 @@ static PyMethodDef module_functions[] = {
      METH_NOARGS, enumerate_doc},
     {"get_current",             (PyCFunction)interp_get_current,
      METH_NOARGS, get_current_doc},
+    {"is_running",              (PyCFunction)interp_is_running,
+     METH_VARARGS, is_running_doc},
 
     {"run_string",              (PyCFunction)interp_run_string,
      METH_VARARGS, run_string_doc},