chore(python): create thread_safety doc (#517)

busunkim96 · web-flow · commit 09c48461232c · 2020-05-05T10:06:52.000-07:00
This will be included in index.rst files. See https://github.com/googleapis/python-bigtable/pull/26/files
diff --git a/synthtool/gcp/templates/python_library/docs/multiprocessing.rst b/synthtool/gcp/templates/python_library/docs/multiprocessing.rst
@@ -0,0 +1,7 @@
+.. note::
+
+   Because this client uses :mod:`grpcio` library, it is safe to
+   share instances across threads. In multiprocessing scenarios, the best
+   practice is to create client instances *after* the invocation of
+   :func:`os.fork` by :class:`multiprocessing.Pool` or
+   :class:`multiprocessing.Process`.
