[FLINK-19519] [Runtime/Configuration] Support port range for Taskmanager data port configuration

[kien-truong]

What is the purpose of the change

This change adds support for setting a port range for a TaskManager data port, which allows multiple TaskManager to run on the same machine without having to use a random port.

Brief change log

• Change value type of taskmanager.data.bind-port from Integer to String.
• Use NetUtils.getPortRangeFromString to generate the list of ports that can be used from the value of taskmanager.data.bind-port
• When starting up TaskManager's NettyServer, try to bind to the ports from the configured range sequentially, returning on the first success.
• Add documents for previously undocumented taskmanager.data.bind-port

Verifying this change

• NetUtils.getPortRangeFromString is reused and already covered by existing tests.
• Add basic unittest: NettyServerMultiPortsTest, to verify that you can start 2 NettyServer concurrently without conflict by setting multiple ports in taskmanager.data.bind-port

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? docs

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Last check on commit 3031e1c (Fri May 28 09:10:45 UTC 2021)

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[cuspymd]

It looks like serverPortRangeIterator can be created using serverPortRange, but is there a reason to keep both fields?

[kien-truong]

Originally, serverPort was used to generate the Netty thread group name. So when I replace serverPort with serverPortRangeIterator, I also include serverPortRange for that purpose.

[cuspymd]

The point of my question is, isn't one field enough? For example, if there is only the serverPortRange field, can't the iterator be created at the desired time using a getter method?

[kien-truong]

Because NetUtils.getPortRangeFromString also does validation, the iterator is generated during configuration parsing phase, so that if there's any configuration error, the user will be notified earlier.