rps degradation when using https.

[cedriclecoz]

Hi all,

Since a few week, the server i am running against is upping it's security, they enabled HTTPS, I have been asked to run my tests over HTTPS, to load this new 'feature'.

On Http, I have been able to load a 1000Clients at a Client per sec rate without any problem.
Once I enable Https, for the few first clients all seems well, but as clients are spawned, the spawning rate is falling.

For example when I have 20 clients running, the next one may take 3-5secs to be spawned.

Just in case, to be sure the problem is not on our server,
I did a quick locust file trying to do gets on a few public servers, which can be ddl at the following link.
https://drive.google.com/file/d/0Bwj-3cp-XeYcY19CbnFuU2VKR3M/view?usp=sharing

To launch, I use: locust -f test_https.py -H https://www.google.com.
40 clients rate: 1cl/sec
Last run I did, I saw a delay of 7 sec between clients 46 and 47

I did add a profiler to locust, the differents method of sslSockets seems to take lots of time.

ncalls tottime percall cumtime percall filename:lineno(function)
1357 37.451 0.028 37.451 0.028 {method 'read' of '_ssl._SSLSocket' objects}
92 18.705 0.203 18.705 0.203 {method 'do_handshake' of '_ssl._SSLSocket' objects}

Is it a known problem ? Maybe i am just missing a patch or something (I hope so, but...)

About my system, I have the same problem in Ubuntu or Centos7, I am running on a pyenv environment, with python 2.7.10. I am working off the following tags:

g/greenlet/greenlet-0.4.7.zip
g/gevent/gevent-1.0.2.tar.gz
W/Werkzeug/Werkzeug-0.10.4.tar.gz
M/MarkupSafe/MarkupSafe-0.23.tar.gz
J/Jinja2/Jinja2-2.7.3.tar.gz 
i/itsdangerous/itsdangerous-0.24.tar.gz
F/Flask/Flask-0.10.1.tar.gz
r/requests/requests-2.7.0.tar.gz
m/msgpack-python/msgpack-python-0.4.6.tar.gz
l/locustio/locustio-0.7.3.tar.gz
p/pyzmq/pyzmq-14.7.0.tar.gz
b/backports.ssl_match_hostname/backports.ssl_match_hostname-3.4.0.2.tar.gz
s/six/six-1.9.0.tar.gz

If anyone has an idea as to how I can get out of this problem, i am all ear :)

Many thanks,

Cedric.

Just in case, the full link to the profiler, if s/o can understand it better than me:
https://drive.google.com/file/d/0Bwj-3cp-XeYcWWVPWnREeWdSMkU/view?usp=sharing

[cgoldberg]

Is it a known problem ?

it's not a problem, but rather the way secure communication works. There is overhead to encryption and cipher negotiation vs. sending plaintext requests. I would expect to see some level of degradation.