Issue #6064: Add a `daemon` keyword argument to the threading.Thread

and multiprocessing.Process constructors in order to override the
default behaviour of inheriting the daemonic property from the current
thread/process.

4 files changed, 33 insertions, 16 deletions

diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py
index b56a061..3fb9ff6 100644
--- a/Lib/multiprocessing/process.py
+++ b/Lib/multiprocessing/process.py
@@ -91,12 +91,16 @@ class Process(object):
     '''
     _Popen = None
 
-    def __init__(self, group=None, target=None, name=None, args=(), kwargs={}):
+    def __init__(self, group=None, target=None, name=None, args=(), kwargs={},
+                 *, daemon=None):
         assert group is None, 'group argument must be None for now'
         count = next(_current_process._counter)
         self._identity = _current_process._identity + (count,)
         self._authkey = _current_process._authkey
-        self._daemonic = _current_process._daemonic
+        if daemon is not None:
+            self._daemonic = daemon
+        else:
+            self._daemonic = _current_process._daemonic
         self._tempdir = _current_process._tempdir
         self._parent_pid = os.getpid()
         self._popen = None
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index 465a831..d154fce 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -163,6 +163,18 @@ class _TestProcess(BaseTestCase):
         self.assertEqual(current.ident, os.getpid())
         self.assertEqual(current.exitcode, None)
 
+    def test_daemon_argument(self):
+        if self.TYPE == "threads":
+            return
+
+        # By default uses the current process's daemon flag.
+        proc0 = self.Process(target=self._test)
+        self.assertEquals(proc0.daemon, self.current_process().daemon)
+        proc1 = self.Process(target=self._test, daemon=True)
+        self.assertTrue(proc1.daemon)
+        proc2 = self.Process(target=self._test, daemon=False)
+        self.assertFalse(proc2.daemon)
+
     @classmethod
     def _test(cls, q, *args, **kwds):
         current = cls.current_process()
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index ecbbdbf..13a428d 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -427,6 +427,14 @@ class ThreadTests(BaseTestCase):
         t.daemon = True
         self.assertTrue('daemon' in repr(t))
 
+    def test_deamon_param(self):
+        t = threading.Thread()
+        self.assertFalse(t.daemon)
+        t = threading.Thread(daemon=False)
+        self.assertFalse(t.daemon)
+        t = threading.Thread(daemon=True)
+        self.assertTrue(t.daemon)
+
 
 class ThreadJoinOnShutdown(BaseTestCase):
 
diff --git a/Lib/threading.py b/Lib/threading.py
index fd93f74..cb09afa 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -622,7 +622,7 @@ class Thread(_Verbose):
     #XXX __exc_clear = _sys.exc_clear
 
     def __init__(self, group=None, target=None, name=None,
-                 args=(), kwargs=None, verbose=None):
+                 args=(), kwargs=None, verbose=None, *, daemon=None):
         assert group is None, "group argument must be None for now"
         _Verbose.__init__(self, verbose)
         if kwargs is None:
@@ -631,7 +631,10 @@ class Thread(_Verbose):
         self._name = str(name or _newname())
         self._args = args
         self._kwargs = kwargs
-        self._daemonic = self._set_daemon()
+        if daemon is not None:
+            self._daemonic = daemon
+        else:
+            self._daemonic = current_thread().daemon
         self._ident = None
         self._started = Event()
         self._stopped = False
@@ -648,10 +651,6 @@ class Thread(_Verbose):
             self._block.__init__()
         self._started._reset_internal_locks()
 
-    def _set_daemon(self):
-        # Overridden in _MainThread and _DummyThread
-        return current_thread().daemon
-
     def __repr__(self):
         assert self._initialized, "Thread.__init__() was not called"
         status = "initial"
@@ -948,15 +947,12 @@ class _Timer(Thread):
 class _MainThread(Thread):
 
     def __init__(self):
-        Thread.__init__(self, name="MainThread")
+        Thread.__init__(self, name="MainThread", daemon=False)
         self._started.set()
         self._set_ident()
         with _active_limbo_lock:
             _active[self._ident] = self
 
-    def _set_daemon(self):
-        return False
-
     def _exitfunc(self):
         self._stop()
         t = _pickSomeNonDaemonThread()
@@ -988,7 +984,7 @@ def _pickSomeNonDaemonThread():
 class _DummyThread(Thread):
 
     def __init__(self):
-        Thread.__init__(self, name=_newname("Dummy-%d"))
+        Thread.__init__(self, name=_newname("Dummy-%d"), daemon=True)
 
         # Thread._block consumes an OS-level locking primitive, which
         # can never be used by a _DummyThread.  Since a _DummyThread
@@ -1000,9 +996,6 @@ class _DummyThread(Thread):
         with _active_limbo_lock:
             _active[self._ident] = self
 
-    def _set_daemon(self):
-        return True
-
     def join(self, timeout=None):
         assert False, "cannot join a dummy thread"