aditya-gupta36 commented on code in PR #640:
URL: https://github.com/apache/atlas/pull/640#discussion_r3534585413
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addons/hbase-bridge/pom.xml:
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@@ -297,6 +415,20 @@
<build>
<plugins>
+ <!-- Parent disables Failsafe forking (forkCount=0). Fork IT JVM
for stable Atlas client + Hadoop minicluster. -->
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-failsafe-plugin</artifactId>
Review Comment:
Why maven-failsafe-plugin?
The parent POM sets forkCount=0, so all ITs run inside the Maven JVM with
one mixed classpath. After the Jersey 2 upgrade, bridge ITs hit classpath
conflicts: shaded atlas-client-v2-shaded (relocated JAX-RS →
NoSuchMethodError), duplicate Jackson providers, and Hive changing the thread
context class loader during SessionState.start().
We override Failsafe per module with forkCount=1, reuseForks=false, and
targeted classpathDependencyExcludes. Without these overrides, CI shows
failures like LinkageError on ClientBuilder, shaded...RuntimeType
NoSuchMethodError, and (on JDK 17) AppClassLoader cannot be cast to
URLClassLoader in Hive ITs.
Classloader issue — why it exists?
"Class loader casting to URLClassLoader succeeds in Java 8 but fails in Java
9+ due to the internal modularity changes; the modern application class loader
(jdk.internal.loader.ClassLoaders$AppClassLoader) no longer extends
URLClassLoader."
Why HiveITSystemClassLoader.java was added?
A custom system class loader installed at JVM startup so Hive’s
SessionState.class.getClassLoader() returns a real URLClassLoader:
ITs also call SessionState.start() via the same Hive 3.1.3 code path. On JDK
17, Hive unconditionally casts SessionState.class.getClassLoader() to
URLClassLoader. The default JDK 9+ app loader is not a URLClassLoader, so
@BeforeClass setUp() fails before any test runs.
HiveITSystemClassLoader is a test-only system class loader (via
-Djava.system.class.loader) that makes that cast succeed. It is activated only
on JDK 9+ through the hive-it-jdk17 profile and requires forkCount=1.
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