cameronlee314 commented on a change in pull request #1173: SAMZA-2333: [AM
isolation] Use cytodynamics classloader to launch job coordinator
URL: https://github.com/apache/samza/pull/1173#discussion_r333755913
##########
File path:
samza-core/src/main/java/org/apache/samza/clustermanager/ClusterBasedJobCoordinator.java
##########
@@ -406,10 +409,72 @@ ContainerProcessManager
createContainerProcessManager(ClassLoader classLoader) {
}
/**
- * The entry point for the {@link ClusterBasedJobCoordinator}
- * @param args args
+ * The entry point for the {@link ClusterBasedJobCoordinator}.
*/
public static void main(String[] args) {
+ boolean isolationEnabled =
+
Boolean.parseBoolean(System.getenv(ShellCommandConfig.ENV_APPLICATION_MASTER_ISOLATION_ENABLED()));
+ if (!isolationEnabled) {
+ // no isolation enabled, so can just execute
runClusterBasedJobCoordinator directly
+ runClusterBasedJobCoordinator(args);
+ } else {
+ runWithIsolatedClassLoader(args);
+ }
+ }
+
+ /**
+ * Execute the coordinator using a separate isolated classloader.
+ */
+ private static void runWithIsolatedClassLoader(String[] args) {
+ ClassLoader isolatedClassLoader = new
IsolatingClassLoaderFactory().buildClassLoader();
+
+ // need to use the isolated classloader to load ClusterBasedJobCoordinator
and then run using that new class
+ Class<?> isolatedClusterBasedJobCoordinatorClass;
+ try {
+ isolatedClusterBasedJobCoordinatorClass =
+
isolatedClassLoader.loadClass(ClusterBasedJobCoordinator.class.getName());
+ } catch (ClassNotFoundException e) {
+ throw new SamzaException(
+ "Isolation was enabled, but unable to find
ClusterBasedJobCoordinator in isolated classloader", e);
+ }
+
+ // save the current context classloader so it can be reset after finishing
the call to runClusterBasedJobCoordinator
+ ClassLoader previousContextClassLoader =
Thread.currentThread().getContextClassLoader();
+ // this is needed because certain libraries use the context classloader
+ Thread.currentThread().setContextClassLoader(isolatedClassLoader);
+
+ try {
+
executeRunClusterBasedJobCoordinatorForClass(isolatedClusterBasedJobCoordinatorClass,
args);
+ } finally {
+ // reset the context class loader
Review comment:
Good practice, and might be important when multiple unit tests from the same
thread. Added a little more context to the comment.
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