Parallel execution mode is inconsistent &/or not efficient

Hi Katalon Dev Team,

I’m trying to implement parallel execution for web and API 6 automation tests, I can see rest API tests consistently working fine whereas web-ui automation tests throwing different errors for every execution.

Execution Mode: Parallel Execution
Number of API tests: 3
Number of WebUI tests: 3
Katalon Studio V 7.7.2
OS : Win 10

Per current Katalon documentation &/or Katalon Community responses, I tried below options:

  1. Tweak JVM GC parameters
    Open katalon.ini then add these JVM options:
    These options will help Java Garbage Collector manages the unused objects better and reduce JVM heap size.

  2. Limit the number of allowed threads for parallel executions, (2 threads), still no luck

3.Tweaking WebUI Settings
Customized page load timeout:
wait for 20 seconds
Delay between actions: 30 seconds

After above setting web-ui, Parallel execution for web-ui automation tests failing randomly.

Could you advice what could be causing this inconsistency?

I’ve noticed the same thing and have had to switch the Test Suite Collection playback mode to Sequential. Test Suite Collection Parallel playback was working fine last week in Chrome 86.0.4280.198. Since the Chrome 87.0.4280.66 update earlier this week (11/17/20), parallel playback has been prone to errors and generally untrustworthy. I’ve entered a Support ticket for the issue, as well.