fix: only require barrier mode if more than one partition is trained on

[eisber]

What changes are proposed in this pull request?

only require barrier mode if more than one partition is trained on

[eisber]

/azp run

[github-actions[bot]]

Hey @eisber :wave:! Thank you so much for contributing to our repository :raised_hands:. Someone from SynapseML Team will be reviewing this pull request soon.

We use semantic commit messages to streamline the release process. Before your pull request can be merged, you should make sure your first commit and PR title start with a semantic prefix. This helps us to create release messages and credit you for your hard work!

Examples of commit messages with semantic prefixes:

• fix: Fix LightGBM crashes with empty partitions
• feat: Make HTTP on Spark back-offs configurable
• docs: Update Spark Serving usage
• build: Add codecov support
• perf: improve LightGBM memory usage
• refactor: make python code generation rely on classes
• style: Remove nulls from CNTKModel
• test: Add test coverage for CNTKModel

To test your commit locally, please follow our guild on building from source. Check out the developer guide for additional guidance on testing your change.

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[codecov-commenter]

Codecov Report

Merging #1912 (ba4856b) into master (3c09702) will decrease coverage by 0.55%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1912      +/-   ##
==========================================
- Coverage   86.81%   86.27%   -0.55%     
==========================================
  Files         301      301              
  Lines       15783    15783              
  Branches      848      842       -6     
==========================================
- Hits        13702    13616      -86     
- Misses       2081     2167      +86     

Impacted Files	Coverage Δ
.../azure/synapse/ml/vw/VowpalWabbitBaseLearner.scala	86.20% <100.00%> (ø)

... and 10 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[mhamilton723]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).