What is the relationship between the setting “max concurrent instances” and Selenium Grid settings MaxInstances and MaxSessions?

Product Forums Katalon Studio
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1

I am looking for a clear explanation for the purpose of the “Max concurrent instances” setting for a test suite collection as it applies to Selenium Grid MaxInstances and MaxSessions settings.

2

i suppose it is related to parallel execution … e.g. if you have a collection with 5 suites but you set that value to 2, it will run only 2 threads at a time … once any suite is finished will start next one … and so on, until the queue is depleted.
Never tried, feel free to play with.

4

@roadbike
This is the answer from the Katalon technical team. I re-post it here.

In Katalon Studio,

The max concurrent instances of the parallel executions of a test suite collection are the number of test suites will be executed at the same time (https://docs.katalon.com/katalon-studio/docs/selenium-grid-integration.html).

For example, a test suite collection has 20 test suites and the max concurrent instances are 8 that means only 8 test suites will be executed at the same time, the rest will be in a waiting queue.

In Selenium Grid,

Selenium Grid is a proxy server that makes it easy to run tests in parallel on multiple machines. MaxInstances and MaxSessions are the parameters that describe the ability of the Selenium Grid Serve to serve the remote client. When connecting Katalon Studio with Selenium Grid using Remote execution (https://docs.katalon.com/katalon-studio/docs/selenium-grid-integration.html), KS now is a Java client that requests the server running script on the browsers of registered nodes.

  • Example #1:
    In KS: 20 test suites with Chrome and the max concurrent instances are 10.
    In Selenium Grid: MaxInstances is 5, MaxSessions is 10.
    KS will launch 10 test suites that request the Selenium Grid to open 10 Chrome browsers. Selenium Grid will only launch 5 Chrome browsers at the same time in this case because MaxInstances is 5.

  • Example #2:
    In KS: 20 test suites with Chrome and the max concurrent instances are 10.
    In Selenium Grid: MaxInstances is 10, MaxSessions is 5.
    KS will launch 10 test suites that request the Selenium Grid to open 10 Chrome browsers. Selenium Grid will only launch 5 Chrome browsers at the same time in this case because MaxSessions is 5.

  • Example #3:
    In KS: 10 test suites include 5 with Chrome, 5 with Firefox and the max concurrent instances are 10.
    In Selenium Grid: MaxInstances is 5, MaxSessions is 10.
    KS will launch 10 test suites that request the Selenium Grid to open 5 Chrome browsers and 5 Firefox browsers. Selenium Grid will launch 5 Chrome browsers and 5 Firefox browsers at the same time in this case.

  • Example #4:
    In KS: 10 test suites include 5 with Chrome, 5 with Firefox and the max concurrent instances are 10.
    In Selenium Grid: MaxInstances is 5, MaxSessions is 8.
    KS will launch 10 test suites that request the Selenium Grid to open 5 Chrome browsers and 5 Firefox browsers. Selenium Grid will only launch 8 browsers at the same time because MaxSessions is 8.

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