Use os.register_at_fork instead of monkey patching fork for python > 3.6

clearml/binding/environ_bind.py

@@ -89,6 +89,7 @@ class SimpleQueueWrapper(object):
 
 class PatchOsFork(object):
     _original_fork = None
+    _registered_fork_callbacks = False
     _current_task = None
     _original_process_run = None
 
@@ -104,13 +105,20 @@ class PatchOsFork(object):
         # noinspection PyBroadException
         try:
             # only once
-            if cls._original_fork:
+            if cls._registered_fork_callbacks or cls._original_fork:
                 return
+            try:
+                os.register_at_fork(before=PatchOsFork._fork_callback_before,
+                                    after_in_child=PatchOsFork._fork_callback_after_child)
+                cls._registered_fork_callbacks = True
+            except Exception:
+                # python <3.6
                 if six.PY2:
                     cls._original_fork = staticmethod(os.fork)
                 else:
                     cls._original_fork = os.fork
                 os.fork = cls._patched_fork
+
         except Exception:
             pass
 
@@ -182,10 +190,9 @@ class PatchOsFork(object):
                     pass
 
     @staticmethod
-    def _patched_fork(*args, **kwargs):
+    def _fork_callback_before():
         if not PatchOsFork._current_task:
-            return PatchOsFork._original_fork(*args, **kwargs)
-
+            return
         from ..task import Task
 
         # ensure deferred is done, but never try to generate a Task object
@@ -195,15 +202,17 @@ class PatchOsFork(object):
         # noinspection PyProtectedMember
         Task._wait_for_deferred(task)
 
-        ret = PatchOsFork._original_fork(*args, **kwargs)
+    @staticmethod
+    def _fork_callback_after_child():
         if not PatchOsFork._current_task:
-            return ret
-        # Make sure the new process stdout is logged
-        if not ret:
+            return
+
+        from ..task import Task
+
         # force creating a Task
         task = Task.current_task()
         if not task:
-                return ret
+            return
 
         PatchOsFork._current_task = task
         # # Hack: now make sure we setup the reporter threads (Log+Reporter)
@@ -237,4 +246,19 @@ class PatchOsFork(object):
 
         os._exit = _at_exit_callback
 
+
+    @staticmethod
+    def _patched_fork(*args, **kwargs):
+        if not PatchOsFork._current_task:
+            return PatchOsFork._original_fork(*args, **kwargs)
+
+        PatchOsFork._fork_callback_before()
+
+        ret = PatchOsFork._original_fork(*args, **kwargs)
+        if not PatchOsFork._current_task:
+            return ret
+        # Make sure the new process stdout is logged
+        if not ret:
+            PatchOsFork._fork_callback_after_child()
+
         return ret