Re: Recording asynchronous request/response times

Hi Niklas,

On 26 May 2015 at 08:16, nmodin <[email protected]> wrote:

> Hi all,
>
> I need to record the time between requests and responses for a web socker
> server I have and can't really figure out how to achieve this. I have a
>

The Grinder is more designed for pull testing than the push testing
required for web sockets. If you want to test the horizontal scalability of
your web sockets you need to get a lot of threads subscribed to your web
socket and then wait for messages. Depending on the number of sockets, you
may find that if you send a lot of messages (> 50 per Grinder process)
simultaneously to your test harness then all the test threads will need to
wake up at the same time, which causes thread contention and possible GC in
your test harness. See
http://grinder.sourceforge.net/g3/garbage-collection.html for details on
how to monitor and tune GC.

If you want to test latency and not scalability of your web sockets, you
could import your small java client into The Grinder as a callable class
and generate time stamps as part of the web socket payload you are
injecting. On the receiving thread look at the time stamp to calculate how
long it took from send to receive. You can use a custom statistic to log
the latency (
http://stackoverflow.com/questions/23452976/how-to-add-custom-statistics-in-grinder
).

Of course you probably want to know the latency of your web sockets when
you have your peak web socket connections. In the end you may spend a lot
of time confirming your test harness is not the bottleneck. One solution to
this is to use a lot of agents, e.g. run them in the cloud.

Regards,
Gary

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