[Python] Ensure Python module doesn't deadlock/segv on exit, fixes #330

bindings/python/libs/client/__init__.py

@@ -4,3 +4,5 @@
 from .file import File as File
 from .url import URL as URL
 from .copyprocess import CopyProcess as CopyProcess
+
+import XRootD.client.finalize

bindings/python/libs/client/finalize.py

@@ -0,0 +1,35 @@
+#-------------------------------------------------------------------------------
+# Copyright (c) 2012-2014 by European Organization for Nuclear Research (CERN)
+# Author: Michal Simon <michal.simon@cern.ch>
+#-------------------------------------------------------------------------------
+# This file is part of the XRootD software suite.
+#
+# XRootD is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# XRootD is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with XRootD.  If not, see <http://www.gnu.org/licenses/>.
+#
+# In applying this licence, CERN does not waive the privileges and immunities
+# granted to it by virtue of its status as an Intergovernmental Organization
+# or submit itself to any jurisdiction.
+#------------------------------------------------------------------------------
+
+import atexit
+from pyxrootd import client
+
+@atexit.register
+def finalize():
+     """Python atexit handler, will stop all XRootD client threads
+        (XrdCl JobManager, TaskManager and Poller) in order to ensure 
+        no Python APIs are called after the Python Interpreter gets
+        finalized.
+     """
+     client.__XrdCl_Stop_Threads()

bindings/python/src/PyXRootDFinalize.hh

@@ -0,0 +1,50 @@
+//------------------------------------------------------------------------------
+// Copyright (c) 2012-2013 by European Organization for Nuclear Research (CERN)
+// Author: Michal Simon <michal.simon@cern.ch>
+//------------------------------------------------------------------------------
+// This file is part of the XRootD software suite.
+//
+// XRootD is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// XRootD is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with XRootD.  If not, see <http://www.gnu.org/licenses/>.
+//
+// In applying this licence, CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+//------------------------------------------------------------------------------
+#ifndef BINDINGS_PYTHON_SRC_PYXROOTDFINALIZE_HH_
+#define BINDINGS_PYTHON_SRC_PYXROOTDFINALIZE_HH_
+
+#include "PyXRootD.hh"
+
+#include "XrdCl/XrdClDefaultEnv.hh"
+#include "XrdCl/XrdClPostMaster.hh"
+
+namespace PyXRootD
+{
+
+  //----------------------------------------------------------------------------
+  //! Waits until XrdCl JobManager, TaskManager and Poller will stop gracefully.
+  //!
+  //! To be used in Python native atexit handler in order to make sure there are
+  //! no outstanding threads after the Python interpreter got finalized.
+  //----------------------------------------------------------------------------
+  PyObject* __XrdCl_Stop_Threads( PyObject *self, PyObject* )
+  {
+    Py_BEGIN_ALLOW_THREADS
+    XrdCl::DefaultEnv::GetPostMaster()->Stop();
+    Py_END_ALLOW_THREADS
+    Py_RETURN_NONE;
+  }
+}
+
+#endif /* BINDINGS_PYTHON_SRC_PYXROOTDFINALIZE_HH_ */

bindings/python/src/PyXRootDModule.cc

@@ -27,6 +27,7 @@
 #include "PyXRootDFile.hh"
 #include "PyXRootDCopyProcess.hh"
 #include "PyXRootDURL.hh"
+#include "PyXRootDFinalize.hh"
 
 namespace PyXRootD
 {
@@ -40,7 +41,9 @@ namespace PyXRootD
   //----------------------------------------------------------------------------
   static PyMethodDef module_methods[] =
     {
-      { NULL } /* Sentinel */
+      // The finalization routine used in atexit handler.
+      { "__XrdCl_Stop_Threads", __XrdCl_Stop_Threads, METH_NOARGS, "Stop XrdCl threads." },
+      { NULL, NULL, 0, NULL }
     };
 
 #if PY_MAJOR_VERSION >= 3