What mean for these process async properties (help!)

Flowable Engine
1

Hi,

  1. In this url: https://www.flowable.org/docs/userguide/index.html#springBootFlowableProperties
    I saw something like this. what mean for these properties?
flowable.process.async.executor.max-async-jobs-due-per-acquisition=1 # ???
flowable.process.async.executor.retry-wait-time-in-millis=500 # ???
  1. In my process, I have some ServiceTasks which will run long time, and I set my ServiceTask with triggerable and async properties. I use message to trigger the process.
    Now, I don’t known whether async thread will do retry during ServiceTask is executing. How to control async thread retry?

thanks.