SPARK-1934 [CORE] "this" reference escape to "selectorThread" during construction in ConnectionManager

[srowen]

This change reshuffles the order of initialization in ConnectionManager so that the last thing that happens is running selectorThread, which invokes a method that relies on object state in ConnectionManager

@zsxwing also reported a similar problem in BlockManager in the JIRA, but I can't find a similar pattern there. Maybe it was subsequently fixed?

[SparkQA]

Test build #26170 has started for PR 4225 at commit c4dec3b.

• This patch merges cleanly.

[SparkQA]

Test build #26170 has finished for PR 4225 at commit c4dec3b.

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

[AmplabJenkins]

Test PASSed.
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[pwendell]

@zsxwing - want to take a look at this?

[zsxwing]

LGTM.

@zsxwing also reported a similar problem in BlockManager in the JIRA, but I can't find a similar pattern there. Maybe it was subsequently fixed?

I checked the history. It's already fixed in #3087

[pwendell]

Thanks @srowen and @zsxwing.