From 5185ce67b59045e20c1975319527b1ffbe705b20 Mon Sep 17 00:00:00 2001
From: Jake Cobb <jake.cobb@gmail.com>
Date: Wed, 23 Jan 2019 15:12:45 -0500
Subject: [PATCH] Python: Init container owner attribute in thread-safe way

---
 Lib/python/pycontainer.swg | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/Lib/python/pycontainer.swg b/Lib/python/pycontainer.swg
index f77c7cb34..b90068466 100644
--- a/Lib/python/pycontainer.swg
+++ b/Lib/python/pycontainer.swg
@@ -36,8 +36,17 @@
 
 %include <std_except.i>
 
-%fragment("reference_container_owner", "header") {
+%fragment("container_owner_attribute_init", "init") {
+  // thread safe initialization
+  swig::container_owner_attribute();
+}
+%fragment("reference_container_owner", "header", fragment="container_owner_attribute_init") {
 namespace swig {
+  PyObject* container_owner_attribute() {
+    static PyObject* attr = SWIG_Python_str_FromChar("__owner");
+    return attr;
+  }
+
   /**
    * Call to add a back-reference to the owning object when returning a 
    * reference from a container.  Will only set the reference if <code>child</code> 
@@ -46,10 +55,9 @@ namespace swig {
    * @return if the reference was set or not
    */
   bool reference_container_owner(PyObject* child, PyObject* owner) {
-    static PyObject* attr = SWIG_Python_str_FromChar("__owner");
     SwigPyObject* swigThis = SWIG_Python_GetSwigThis(child);
     if (swigThis && (swigThis->own & SWIG_POINTER_OWN) != SWIG_POINTER_OWN) {
-      PyObject_SetAttr(child, attr, owner);
+      PyObject_SetAttr(child, container_owner_attribute(), owner);
       return true;
     }
     return false;