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• Flink should rescale immediately only if last rescale was done more than scaling-interval.min ago.
• Otherwise it should schedule a rescale at (now + scaling-interval.min) point in time. It is equivalent to resetting the cooldown period when new slots arrive during a cooldown period. Indeed, we decided to lower the scaling-interval.min default value to be more reactive (cf compatibility part), resetting the period allows to protect against too frequent rescales. 
• The rescale is done like this: 
  • if minimum scaling requirements are met (AdaptiveScheduler#shouldRescale), the job is restarted with new parallelism (as before)
  • if minimum scaling requirements are not met but last rescale was done more than scaling-interval.max ago, a rescale is forced.

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So this FLIP proposes setting defaults values to jobmanager.adaptive-scheduler.scaling-interval.min = 30s and no jobmanager.adaptive-scheduler.scaling-interval.max (force scaling disabled). Indeed, by default we prefer to favor lower numbers scaling-interval.min (for smooth rescale experiencemore reactive rescaling) and consider higher numbers as exceptions set by let the users when increase the value when they have high workloads.

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