Clarity on Flink 1.5 Rescale mechanism

Posted by Sampath Bhat on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Clarity-on-Flink-1-5-Rescale-mechanism-tp20689.html

Hello

In flink 1.5 release notes - https://flink.apache.org/news/2018/05/25/release-1.5.0.html#release-notes 

Various Other Features and Improvements:

Applications can be rescaled without manually triggering a savepoint. Under the hood, Flink will still take a savepoint, stop the application, and rescale it to the new parallelism.

What exactly does this statement mean?

How to rescale the application ?

If i'm running my flink job application with parallelism of 5 and then I execute the following command

flink run <jar_path> -p 10 then will the application rescale to 10 parallelism?

Adding on what will be the behavior in flink 1.5 if I increase the number of task manager in a flink cluster?

So if i have a flink job running on flink cluster having 1 task manager and i increase the number of task manager to 2 will the flink rescale the flink job also or will the flink job be unaffected?