[SPARK-28112] Fix Kryo exception perf. bottleneck in tests due to absence of ML/MLlib classes

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 3.0.0
• Component/s: Spark Core, Tests
• Assignee: Josh Rosen
• Reporter: Xiao Li
• Created: 19/Jun/19 22:18
• Updated: 20/Jun/19 02:10
• Resolved: 20/Jun/19 02:06

Description

In a nutshell, it looks like the absence of ML / MLlib classes on the classpath causes code in KryoSerializer to throw and catch ClassNotFoundExceptions whenever instantiating a new serializer in newInstance(). This isn't a performance problem in production (since MLlib is on the classpath there) but it's a huge issue in tests and appears to account for an enormous amount of test time

We can address this problem by reducing the total number of ClassNotFoundExceptions by performing the class existence checks once and storing the results in KryoSerializer instances rather than repeating the checks on each newInstance() call.

Issue Links

• links to: GitHub Pull Request #24916