Merge pull request #3819 from cadop/bullet-client-subprocess-safety

Fix for bullet_client to be used from a class instance during multiprocessing

examples/pybullet/gym/pybullet_utils/bullet_client.py

@@ -1,6 +1,7 @@
 """A wrapper for pybullet to manage different clients."""
 from __future__ import absolute_import
 from __future__ import division
+import os
 import functools
 import inspect
 import pybullet
@@ -21,6 +22,7 @@ class BulletClient(object):
         `pybullet.SHARED_MEMORY` connects to an existing simulation.
     """
     self._shapes = {}
+    self._pid = os.getpid()
     if connection_mode is None:
       self._client = pybullet.connect(pybullet.SHARED_MEMORY, options=options)
       if self._client >= 0:
@@ -34,7 +36,7 @@ class BulletClient(object):
 
   def __del__(self):
     """Clean up connection if not already done."""
-    if self._client>=0:
+    if self._client>=0 and self._pid == os.getpid():
       try:
         pybullet.disconnect(physicsClientId=self._client)
         self._client = -1