[SPARK-10432] spark.port.maxRetries documentation is unclear

[tgravescs]

No description provided.

[SparkQA]

Test build #41971 has finished for PR 8585 at commit 1070031.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

LGTM

[andrewor14]

Yup, looks good.

[holdenk]

Maybe worth mentioning what happens when the port is given a non-specific value as well?

[tgravescs]

I was on the fence about that as it somewhat seemed redundant with the first line, but if people thinks it will help I can add a line like:

Maximum number of retries when binding to a port before giving up.

• When the port is 0 it retries 0 the specified maximum number of retries.
  When a port is non 0, each subsequent retry will
  increment the port used in the previous attempt by 1 before retrying. This
  essentially allows it to try a range of ports from the start port specified
  to port + maxRetries.

@srowen @andrewor14 thoughts?

[andrewor14]

Yeah, sounds a little redundant. I think it's OK given that it's pretty common for 0 to mean a random port. Since we explicitly say (n + 1) only applies to non-0 ports I think it's fine.

[andrewor14]

OK, I'm going to merge this into master.