Add note on concurrent usage of Minio client (#849)

README.md

@@ -51,6 +51,8 @@ minioClient = Minio('play.min.io',
                   secure=True)
 ```
 
+**NOTE on concurrent usage:** The `Minio` object is thread safe when using the Python `threading` library. Specifically, it is **NOT** safe to share it between multiple processes, for example when using `multiprocessing.Pool`. The solution is simply to create a new `Minio` object in each process, and not share it between processes.
+
 
 ## Quick Start Example - File Uploader
 This example program connects to a MinIO object storage server, makes a bucket on the server and then uploads a file to the bucket.

docs/API.md

@@ -64,6 +64,8 @@ __Parameters__
 | `region`  |_string_ | Set this value to override automatic bucket location discovery. (Optional defaults to `None`). |
 | `http_client` |_urllib3.poolmanager.PoolManager_ | Set this value to use custom http client instead of using default http client. (Optional defaults to `None`) |
 
+**NOTE on concurrent usage:** The `Minio` object is thread safe when using the Python `threading` library. Specifically, it is **NOT** safe to share it between multiple processes, for example when using `multiprocessing.Pool`. The solution is simply to create a new `Minio` object in each process, and not share it between processes.
+
 __Example__
 
 ### MinIO

minio/api.py

@@ -144,6 +144,13 @@ class Minio(object):
     :param timeout: Set this value to control how long requests
          are allowed to run before being aborted.
     :return: :class:`Minio <Minio>` object
+
+    **NOTE on concurrent usage:** The `Minio` object is thread safe when using
+    the Python `threading` library. Specifically, it is **NOT** safe to share
+    it between multiple processes, for example when using
+    `multiprocessing.Pool`. The solution is simply to create a new `Minio`
+    object in each process, and not share it between processes.
+
     """
     def __init__(self, endpoint, access_key=None,
                  secret_key=None,