Document connection pooling

[wolever]

Currently it's not clear how – if at all – python-swiftclient pools connections, or if connection pooling is even possible.

The only two references to "pooling" in the documentation are:
- The Service API page: https://docs.openstack.org/developer/python-swiftclient/service-api.html
- The otherwise undocumented ConnectionThreadPoolExecutor: https://docs.openstack.org/developer/python-swiftclient/swiftclient.html#swiftclient.multithreading.ConnectionThreadPoolExecutor

And neither of these answer the question of "how, if at all, are connections pooled".

Specifically, I need to know how connections are pooled because application uses python-swiftclient to connect to a Swift cluster, and I'd like to make sure the application is as responsive as possible.

[Timur Alperovich (timur-alperovich)]

In addition to documentation, python-swiftclient should probably expose the pool_connections option (and the max_pool_size) of the HTTPAdapter used by default in requests (http://docs.python-requests.org/en/master/user/advanced/).

To answer the bug's query, requests uses an HTTPAdapter by default with a pool of 10 connections.

[Mehdi Abaakouk (sileht)]

swiftclient should replace all its custom HTTPConnection by the keystoneauth1 session object.