kie-issue#1738: customize ForkJoinPool to explicitly inherit the cont…

…ext ClassLoader from the parent thread

drools-compiler/src/main/java/org/drools/compiler/builder/impl/KnowledgeBuilderImpl.java

@@ -32,6 +32,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.ForkJoinWorkerThread;
 import java.util.function.Supplier;
 
 import org.drools.base.RuleBase;
@@ -500,10 +501,11 @@ protected PackageRegistryManager getPackageRegistryManager() {
     }
 
     public static class ForkJoinPoolHolder {
-        public static final ForkJoinPool COMPILER_POOL = new ForkJoinPool(); // avoid common pool
+        public static final ForkJoinPool COMPILER_POOL = new ForkJoinPool(Math.min(32767, Runtime.getRuntime().availableProcessors()), pool -> new ForkJoinWorkerThread(pool) {{
+            setContextClassLoader(Thread.currentThread().getContextClassLoader());
+        }}, null, false); // avoid common pool
     }
 
-
     public boolean filterAccepts(ResourceChange.Type type, String namespace, String name) {
         return assetFilter == null || !AssetFilter.Action.DO_NOTHING.equals(assetFilter.accept(type, namespace, name));
     }

drools-compiler/src/test/java/org/drools/compiler/builder/impl/KnowledgeBuilderImplCompilerFJPoolTest.java

@@ -0,0 +1,75 @@
+package org.drools.compiler.builder.impl;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.RecursiveAction;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+public class KnowledgeBuilderImplCompilerFJPoolTest {
+
+    private ClassLoader originalClassLoader;
+    private ClassLoader customClassLoader;
+
+    @BeforeEach
+    void setUp() {
+        // Save the original classloader
+        originalClassLoader = Thread.currentThread().getContextClassLoader();
+
+        // Create a custom classloader for testing
+        customClassLoader = new ClassLoader(ClassLoader.getSystemClassLoader()) {};
+        Thread.currentThread().setContextClassLoader(customClassLoader);
+    }
+
+    @AfterEach
+    void tearDown() {
+        // Restore original classloader
+        Thread.currentThread().setContextClassLoader(originalClassLoader);
+    }
+
+    private static class ClassLoaderCheckTask extends RecursiveAction {
+        private final List<ClassLoader> results;
+        private final int index;
+
+        public ClassLoaderCheckTask(List<ClassLoader> results, int index) {
+            this.results = results;
+            this.index = index;
+        }
+
+        @Override
+        protected void compute() {
+            results.set(index, Thread.currentThread().getContextClassLoader());
+        }
+    }
+
+    @Test
+    void testCompilerPoolClassLoader() throws Exception {
+        int numTasks = 5;
+        List<ClassLoader> results = new ArrayList<>(numTasks);
+        for (int i = 0; i < numTasks; i++) {
+            results.add(null);
+        }
+
+        // Submit tasks to the COMPILER_POOL
+        for (int i = 0; i < numTasks; i++) {
+            KnowledgeBuilderImpl.ForkJoinPoolHolder.COMPILER_POOL.submit(new ClassLoaderCheckTask(results, i));
+        }
+
+        // Wait for completion
+        KnowledgeBuilderImpl.ForkJoinPoolHolder.COMPILER_POOL.awaitQuiescence(1, TimeUnit.SECONDS);
+
+        // Verify all worker threads have the expected classloader
+        for (ClassLoader workerClassLoader : results) {
+            assertSame(
+                    customClassLoader,
+                    workerClassLoader,
+                    "Worker thread should have inherited the custom classloader"
+            );
+        }
+    }
+}