We all know that unfortunately Horizon's performance not good enough in
some cases. That's why we try to fix it on both sides: client-side and
I would like to talk mostly about server-side now. On some views, we use
'futurist' library  to fetch resources from API's in parallel. I've
filed a blueprint for this effort . You can find some work in progress
patches in the Gerrit.
For now, we use futurist.ThreadPoolExecutor in Horizon to fetch resources
from APIs. It requires some specific Apache configuration changes to allow
WSGI app to create threads. It means, our code execution depends on Apache
To avoid this, we can use futurist.GreenThreadPoolExecutor. It
uses eventlet green threads which can be used to speed-up I/O operations
like 'call external API'.
I did very simple performance testing  with proposed patch  for
volumes views. My tests are not ideal but you can see how it's going with
green thread. I propose to switch to the futurist.GreenThreadPoolExecutor
and add 'eventlet.monkey_patch()' call to the wsgi app for Horizon. It will
speed up parallel API calls and make Horizon independent on Apache or other
web server configuration.
I added this topic to the next weekly meeting agenda  so we can discuss
it there too.
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