6.4. Defining the load progression

6.4.1. Randomly generated users

The load progression is set-up by defining several arrival phases:

<load>
  <arrivalphase phase="1" duration="10" unit="minute">
    <users interarrival="2" unit="second"></users>
  </arrivalphase>

  <arrivalphase phase="2" duration="10" unit="minute">
    <users interarrival="1" unit="second"></users>
  </arrivalphase>

  <arrivalphase phase="3" duration="10" unit="minute">
    <users interarrival="0.1" unit="second"></users>
  </arrivalphase>
</load>

With this setup, during the first 10 minutes of the test, a new user will be created every 2 seconds, then during the next 10 minutes, a new user will be created every second, and for the last 10 minutes, 10 users will be generated every second. The test will finish when all users have ended their session.

You can also use arrivalrate instead of interarrival. For example, if you want 10 new users per second, use:

<arrivalphase phase="1" duration="10" unit="minute">
  <users arrivalrate="10" unit="second"></users>
</arrivalphase>

You can limit the number of users started for each phase by using the maxnumber attribute, just like this:

<arrivalphase phase="1" duration="10" unit="minute">
  <users maxnumber="100" arrivalrate="10" unit="second"></users>
</arrivalphase>
<arrivalphase phase="2" duration="10" unit="minute">
  <users maxnumber="200" arrivalrate="10" unit="second"></users>
</arrivalphase>

In this case, only 100 users will be created in the first phases, and 200 more during the second phase.

The complete sequence can be executed several times using the loop attribute in the load tag (loop='2' means the sequence will be looped twice, so the complete load will be executed 3 times) (feature available since version 1.2.2).

The load generated in terms of HTTP requests / seconds will also depend on the mean number of requests within a session (if you have a mean value of 100 requests per session and 10 new users per seconds, the theoretical average throughput will be 1000 requests/ sec).

New in version 1.5.1.

You can also override the probability settings of sessions within a specific phase, using session_setup:

<arrivalphase phase="3" duration="1" unit="minute">
  <session_setup name="http_test_1" probability="80"/>
  <session_setup name="fake"        probability="20"/>
  <users  interarrival="1" unit="second"/>
</arrivalphase>

6.4.2. Statically generated users

If you want to start a given session (see Sessions) at a given time during the test, it is possible since version 1.3.1:

<load>
  <arrivalphase phase="1" duration="10" unit="minute">
    <users interarrival="2" unit="second"></users>
  </arrivalphase>
  <user session="http-example" start_time="185" unit="second"></user>
  <user session="http-example" start_time="10" unit="minute"></user>
  <user session="foo" start_time="11" unit="minute"></user>
</load>
<sessions>
  <session name="http-example" probability="0" type="ts_http">
    <request> <http url="/" method="GET"></http> </request>
  </session>
  <session name="foobar" probability="0" type="ts_http">
    <request> <http url="/bar" method="GET"></http> </request>
  </session>
  <session name="foo" probability="100" type="ts_http">
    <request> <http url="/" method="GET"></http> </request>
  </session>
<sessions>

In this example, we have two sessions, one has a “0” probability (and therefore will not be used in the first phase), and the other 100%. We define 3 users starting respectively 3mn and 5 seconds after the beginning of the test (using the http-example session), one starting after 10 minutes, and a last one starting after 11 minutes (using the foo session this time)

New in version 1.5.1.

If you want to start several sessions at once, and if the name of these sessions starts with the same prefix, you can use a wildcard. Given the previous sessions, this example will start two users (one with foo session, and one with foobar session) at starttime +10s.

<user session="foo*" start_time="10" unit="second"/>

6.4.3. Duration of the load test

By default, tsung will end when all started users have finished their session. So it can be much longer than the duration of arrivalphases. If you want to stop Tsung after a given duration (even if phases are not finished or if some sessions are still actives), you can do this with the duration attribute in load (feature added in 1.3.2):

<load duration="1" unit="hour">
  <arrivalphase phase="1" duration="10" unit="minute">
    <users interarrival="2" unit="second"></users>
  </arrivalphase>
</load>

Currently, the maximum value for duration is a little bit less than 50 days. unit can be second, minute or hour.

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