Open Stack

Hi,

This question is specific to Openstack Swift. I am trying to understand
just how much is the proxy server a bottleneck when multiple clients are
concurrently trying to write to a swift cluster. Has anyone done
experiments to measure this? It'll be great to see some results.

I see that the proxy-server already has a "workers" config option. However,
looks like that is the # of threads in one proxy-server process. Does
having multiple proxy-servers themselves, running on different nodes (and
having some load-balancer in front of them) help in satisfying more
concurrent writes? Or will these multiple proxy-servers also get
bottlenecked on the account/container/obj server?

Also, looking at the code in swift/proxy-server/controllers/obj.py, it
seems that each request that the proxy-server sends to the backend servers
(account/container/obj) is synchronous. It does not send the request and go
back do accept more requests. Is this one of the reasons why write requests
can be slow?

Thanks in advance.
-Shri
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