[FLINK-10995][benchmarks] Use BroadcastRecordWriter for network broadcast benchmarks

[pnowojski]

After merging #7713 we haven't observed the performance improvement in the benchmarks, because broadcasting was not properly configured in the networkBroadcastThroughput benchmark. This PR fixes that.

Local tests shows that the before mentioned PR when tested with this fix, improved the networkBroadcastThroughput throughput from 640 ops/ms to 950 ops/ms.

Verifying this change

This change is already covered by existing tests, such as StreamNetworkThroughputBenchmarkTest and StreamNetworkBroadcastThroughputBenchmarkTest.

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

Thanks a lot for your contribution to the Apache Flink project. I'm the @flinkbot. I help the community
to review your pull request. We will use this comment to track the progress of the review.

Automated Checks

Last check on commit 1c41525 (Wed Oct 16 08:33:51 UTC 2019)

Warnings:

• No documentation files were touched! Remember to keep the Flink docs up to date!

_{Mention the bot in a comment to re-run the automated checks.}

Review Progress

• ❓ 1. The [description] looks good.
• ❓ 2. There is [consensus] that the contribution should go into to Flink.
• ❓ 3. Needs [attention] from.
• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

Please see the Pull Request Review Guide for a full explanation of the review process.

Details

The Bot is tracking the review progress through labels. Labels are applied according to the order of the review items. For consensus, approval by a Flink committer of PMC member is required

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot approve description to approve one or more aspects (aspects: description, consensus, architecture and quality)
• @flinkbot approve all to approve all aspects
• @flinkbot approve-until architecture to approve everything until architecture
• @flinkbot attention @username1 [@username2 ..] to require somebody's attention
• @flinkbot disapprove architecture to remove an approval you gave earlier

[flinkbot]

CI report:

• 1c41525 : SUCCESS Build

[AHeise]

LGTM. A bit odd that the main commit is only 3 lines compared to the first hotfix (i.e., maybe it's not a hotfix but part of the main commit).

[pnowojski]

Yes, I was a bit torn apart by this. I have kept it separated as the RecordWriterBuilder was introduced after the benchmark was created. If it was the other way around, it would have been exposed/returned the way I did it in the first commit (in other words, I think this first commit has a value on it's own without adjusting the benchmark).

But I could be convinced to squash it if you prefer.