[PR] [KYUUBI #7733][UTIL] Fall back to ReflectUtils's own loader when the context loader is null [kyuubi]

["LuciferYang (via GitHub)" <gi...@apache.org>]

LuciferYang opened a new pull request, #7734:
URL: https://github.com/apache/kyuubi/pull/7734

   ### Why are the changes needed?
   
   Closes #7733.
   
   Stacked on #7724; its commit is the first of the two here, and the diff reduces to the second commit once #7724 merges.
   
   `ReflectUtils.isClassLoadable` defaults its loader to the thread context classloader. On a thread whose context loader is null, `DynClasses.builder().loader(null)` resolves the name through `Class.forName(name, true, null)`, which delegates to the bootstrap loader. The bootstrap loader sees only JDK classes, so the probe answers `false` for every application class, including Kyuubi's own, even when it is loadable through the loader that defined `ReflectUtils`.
   
   This falls back to `ReflectUtils`'s own classloader when the effective loader is null, matching Spark's `getContextOrSparkClassLoader`. The change is monotonic: a non-null loader behaves exactly as before, and a null loader can only turn a `false` into a `true` (an application class becomes loadable), never the reverse. Repository threads carry a non-null context loader under normal startup, so this is defensive hardening for embedded hosts (a JNI invocation that never sets a context loader, a container framework that clears it) and third-party callers of this public helper.
   
   ### How was this patch tested?
   
   Added a `ReflectUtilsSuite` case that sets the thread context loader to null (restored in `finally`) and asserts an application class is loadable while a non-existent one is not. It fails without the fallback, since the bootstrap loader cannot see the class.
   
   ```
   build/mvn test -pl kyuubi-util-scala -am
   build/mvn scalastyle:check spotless:check -pl kyuubi-util-scala -am
   ```
   
   Module green on Zulu 17.0.18 (23/23), scalastyle 0 errors, spotless clean.
   
   ### Was this patch assisted by generative AI tooling?
   
   Assisted-by: Claude Opus 4.8
   


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Re: [PR] [KYUUBI #7733][UTIL] Fall back to ReflectUtils's own loader when the context loader is null [kyuubi]

["pan3793 (via GitHub)" <gi...@apache.org>]

pan3793 commented on PR #7734:
URL: https://github.com/apache/kyuubi/pull/7734#issuecomment-6413692011

   sorry for the late, could you rebase to resolve conflicts?


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