HSEARCH-3725 Add a reproducer for Gson bug 764

google/gson#764

integrationtest/backend/elasticsearch/src/test/java/org/hibernate/search/integrationtest/backend/elasticsearch/gson/ElasticsearchGsonConcurrencyIT.java

@@ -0,0 +1,108 @@
+/*
+ * Hibernate Search, full-text search for your domain model
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.search.integrationtest.backend.elasticsearch.gson;
+
+import org.hibernate.search.engine.backend.document.IndexFieldReference;
+import org.hibernate.search.engine.backend.document.IndexObjectFieldReference;
+import org.hibernate.search.engine.backend.document.model.dsl.IndexSchemaElement;
+import org.hibernate.search.engine.backend.document.model.dsl.IndexSchemaObjectField;
+import org.hibernate.search.integrationtest.backend.tck.testsupport.util.rule.SearchSetupHelper;
+import org.hibernate.search.util.impl.test.annotation.TestForIssue;
+
+import org.junit.Rule;
+import org.junit.Test;
+
+/**
+ * Reproducer for HSEARCH-3725,
+ * which is caused by a bug in Gson: https://github.com/google/gson/issues/764
+ * <p>
+ * The bug happens very rarely, so we run the test multiple times,
+ * but there's no guarantee we will actually reproduce it.
+ * On my machine (8 CPU cores), I've seen the test run hundreds of times in a row
+ * without the bug occurring even once.
+ * But sometimes, if you're lucky, it will occur (I've seen it).
+ * <p>
+ * For the bug to occur, we need to:
+ * <ul>
+ *     <li>Initialize multiple indexes in parallel</li>
+ *     <li>Serialize a mapping, or at least convert it to JsonElements, as part of index initialization</li>
+ * </ul>
+ * If we reach some state where two threads are initializing the same Gson TypeAdapter simultaneously,
+ * there is a small chance FutureTypeAdapter#write(JsonWriter, Object)
+ * will see a null adapter and throw an exception.
+ */
+@TestForIssue(jiraKey = "HSEARCH-3725")
+public class ElasticsearchGsonConcurrencyIT {
+
+	/*
+	 * Please keep these constants reasonably low so that routine builds don't take forever:
+	 * test duration will be proportional to REPRODUCER_ATTEMPTS*INDEX_COUNT_PER_ATTEMPT.
+	 * However, you will need to raise them in your local copy of the code
+	 * to have a high chance of reproducing the bug.
+	 */
+	private static final int REPRODUCER_ATTEMPTS = 20;
+	// This must be at least 2, but you don't need more than the number of CPU cores.
+	private static final int INDEX_COUNT_PER_ATTEMPT = 4;
+
+	private static final String INDEX_NAME_PREFIX = "IndexName_";
+
+	@Rule
+	public SearchSetupHelper setupHelper = new SearchSetupHelper();
+
+	@Test
+	public void repeatedlyStartMultipleIndexesSerializingWithGsonInParallel() {
+		for ( int i = 0; i < REPRODUCER_ATTEMPTS; i++ ) {
+			startMultipleIndexesSerializingWithGsonInParallel();
+			setupHelper.cleanUp();
+		}
+	}
+
+	private void startMultipleIndexesSerializingWithGsonInParallel() {
+		SearchSetupHelper.SetupContext setupCtx = setupHelper.start();
+
+		for ( int i = 0; i < INDEX_COUNT_PER_ATTEMPT; i++ ) {
+			setupCtx = setupCtx.withIndex(
+					INDEX_NAME_PREFIX + i,
+					ctx -> new IndexMapping( ctx.getSchemaElement() )
+			);
+		}
+
+		setupCtx.setup();
+	}
+
+	private static class IndexMapping {
+		final ObjectMapping child;
+
+		IndexMapping(IndexSchemaElement root) {
+			// Two levels of nested properties are necessary to reproduce the Gson bug causing HSEARCH-3725
+			child = new ObjectMapping( root, "child", 3 );
+		}
+	}
+
+	private static class ObjectMapping {
+		final IndexObjectFieldReference self;
+		final IndexFieldReference<String> text;
+		final ObjectMapping child;
+
+		ObjectMapping(IndexSchemaElement parent, String name, int depth) {
+			IndexSchemaObjectField objectField = parent.objectField( name );
+			self = objectField.toReference();
+			text = objectField.field(
+					"text",
+					f -> f.asString()
+			)
+					.toReference();
+			if ( depth > 1 ) {
+				child = new ObjectMapping( objectField, name, depth - 1 );
+			}
+			else {
+				child = null;
+			}
+		}
+	}
+
+}

integrationtest/backend/tck/src/main/java/org/hibernate/search/integrationtest/backend/tck/testsupport/util/rule/SearchSetupHelper.java

@@ -86,23 +86,28 @@ private Statement statement(final Statement base, final Description description)
 		Statement wrapped = new Statement() {
 			@Override
 			public void evaluate() throws Throwable {
-				try ( Closer<RuntimeException> closer = new Closer<>() ) {
-					try {
-						base.evaluate();
-					}
-					finally {
-						closer.pushAll(
-								SearchIntegrationPartialBuildState::closeOnFailure, integrationPartialBuildStates );
-						integrationPartialBuildStates.clear();
-						closer.pushAll( SearchIntegration::close, integrations );
-						integrations.clear();
-					}
+				try {
+					base.evaluate();
+				}
+				finally {
+					cleanUp();
 				}
 			}
 		};
 		return delegateRule.apply( wrapped, description );
 	}
 
+	public void cleanUp() {
+		try ( Closer<RuntimeException> closer = new Closer<>() ) {
+			closer.pushAll(
+					SearchIntegrationPartialBuildState::closeOnFailure, integrationPartialBuildStates
+			);
+			integrationPartialBuildStates.clear();
+			closer.pushAll( SearchIntegration::close, integrations );
+			integrations.clear();
+		}
+	}
+
 	public class SetupContext {
 
 		private final ConfigurationPropertyChecker unusedPropertyChecker;