Merge pull request #234 from dw/dmw

Fix one Latch race, one huge leak around fork

docs/ansible.rst

@@ -544,13 +544,13 @@ Setns
 ~~~~~
 
 The ``setns`` method connects to Linux containers via `setns(2)
-<https://linux.die.net/man/2/setns>`_. Unlike ``docker`` and ``lxc`` the
-namespace transition is handled directly, ensuring optimal throughput to the
-child. This is necessary for ``machinectl`` where only PTY channels are
+<https://linux.die.net/man/2/setns>`_. Unlike :ref:`docker` and :ref:`LXC` the
+namespace transition is handled internally, ensuring optimal throughput to the
+child. This is necessary for :ref:`machinectl` where only PTY channels are
 supported.
 
-Utility programs must still be installed to discover the PID of the container's
-root process.
+A utility program must be installed to discover the PID of the container's root
+process.
 
 * ``mitogen_kind``: one of ``docker``, ``lxc`` or ``machinectl``.
 * ``ansible_host``: Name of container as it is known to the corresponding tool

mitogen/core.py

@@ -981,6 +981,7 @@ class Latch(object):
     closed = False
     _waking = 0
     _sockets = []
+    _allsockets = []
 
     def __init__(self):
         self._lock = threading.Lock()
@@ -989,10 +990,9 @@ class Latch(object):
 
     @classmethod
     def _on_fork(cls):
-        while cls._sockets:
-            rsock, wsock = cls._sockets.pop()
-            rsock.close()
-            wsock.close()
+        cls._sockets = []
+        while cls._allsockets:
+            cls._allsockets.pop().close()
 
     def close(self):
         self._lock.acquire()
@@ -1008,11 +1008,14 @@ class Latch(object):
         return len(self._queue) == 0
 
     def _tls_init(self):
-        if self._sockets:
+        # pop() must be atomic, which is true for GIL-equipped interpreters.
+        try:
             return self._sockets.pop()
+        except IndexError:
             rsock, wsock = socket.socketpair()
             set_cloexec(rsock.fileno())
             set_cloexec(wsock.fileno())
+            self._allsockets.extend((rsock, wsock))
             return rsock, wsock
 
     def get(self, timeout=None, block=True):

mitogen/parent.py

@@ -798,7 +798,6 @@ class Context(mitogen.core.Context):
         LOG.debug('%r.shutdown() sending SHUTDOWN', self)
         latch = mitogen.core.Latch()
         mitogen.core.listen(self, 'disconnect', lambda: latch.put(None))
-
         self.send(
             mitogen.core.Message(
                 handle=mitogen.core.SHUTDOWN,
@@ -807,6 +806,7 @@ class Context(mitogen.core.Context):
 
         if wait:
             latch.get()
+        return latch
 
 
 class RouteMonitor(object):

mitogen/setns.py

@@ -77,8 +77,9 @@ def _run_command(args):
 
 def get_docker_pid(path, name):
     args = [path, 'inspect', '--format={{.State.Pid}}', name]
+    output = _run_command(args)
     try:
-        return int(_run_command(args))
+        return int(output)
     except ValueError:
         raise Error("could not find PID from docker output.\n%s", output)
 
@@ -132,7 +133,7 @@ class Stream(mitogen.parent.Stream):
         if lxc_info_path:
             self.lxc_info_path = lxc_info_path
         if machinectl_path:
-            self.machinectl_path = lxc_attach_apth
+            self.machinectl_path = machinectl_path
 
     # Order matters. https://github.com/karelzak/util-linux/commit/854d0fe/
     NS_ORDER = ('ipc', 'uts', 'net', 'pid', 'mnt', 'user')