Add FAQ

docs/FAQ/FAQ.rst

@@ -0,0 +1,66 @@
+
+Qlib FAQ
+############
+
+Qlib Frequently Asked Questions
+================================
+.. contents::
+    :depth: 1
+    :local:
+    :backlinks: none
+
+------
+
+
+1. RuntimeError: An attempt has been made to start a new process before the current process has finished its bootstrapping phase...
+------------------------------------------------------------------------------------------------------------------------------------
+
+.. code-block:: console
+
+    RuntimeError:
+            An attempt has been made to start a new process before the
+            current process has finished its bootstrapping phase.
+
+            This probably means that you are not using fork to start your
+            child processes and you have forgotten to use the proper idiom
+            in the main module:
+
+                if __name__ == '__main__':
+                    freeze_support()
+                    ...
+
+            The "freeze_support()" line can be omitted if the program
+            is not going to be frozen to produce an executable.
+
+This is caused by the limitation of multiprocessing under windows OS. Please refer to `here <https://stackoverflow.com/a/24374798>`_ for more info.
+
+**Solution**: To select a start method you use the ``D.features`` in the if __name__ == '__main__' clause of the main module. For example:
+
+.. code-block:: python
+
+    import qlib
+    from qlib.data import D
+
+
+    if __name__ == "__main__":
+        qlib.init()
+        instruments = ["SH600000"]
+        fields = ["$close", "$change"]
+        df = D.features(instruments, fields, start_time='2010-01-01', end_time='2012-12-31')
+        print(df.head())
+
+
+
+2. qlib.data.cache.QlibCacheException: It sees the key(...) of the redis lock has existed in your redis db now.
+-----------------------------------------------------------------------------------------------------------------
+
+It sees the key of the redis lock has existed in your redis db now. You can use the following command to clear your redis keys and rerun your commands
+
+.. code-block:: console
+
+    $ redis-cli
+    > select 1
+    > flushdb
+
+
+Also, feel free to post a new issue in our GitHub repository. We always look at each case individually and try to find a root cause.

docs/index.rst

@@ -54,6 +54,11 @@ Document Structure
 
    API <reference/api.rst>
 
+.. toctree::
+   :maxdepth: 3
+
+   FAQ <FAQ/FAQ.rst>
+
 .. toctree::
    :maxdepth: 3
    :caption: Change Log: