Avoid creation of SAXParserFactory for every read operation

Includes JAXBContext locking revision (avoiding synchronization) and consistent treatment of DocumentBuilderFactory (in terms of caching as well as locking).

Closes gh-32851

(cherry picked from commit a4c2f29)

Author: jhoeller

spring-oxm/src/main/java/org/springframework/oxm/jaxb/Jaxb2Marshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,8 @@
 import java.util.Date;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.XMLConstants;
 import javax.xml.datatype.Duration;
@@ -192,7 +194,7 @@ public class Jaxb2Marshaller implements MimeMarshaller, MimeUnmarshaller, Generi
 	@Nullable
 	private ClassLoader beanClassLoader;
 
-	private final Object jaxbContextMonitor = new Object();
+	private final Lock jaxbContextLock = new ReentrantLock();
 
 	@Nullable
 	private volatile JAXBContext jaxbContext;
@@ -204,6 +206,12 @@ public class Jaxb2Marshaller implements MimeMarshaller, MimeUnmarshaller, Generi
 
 	private boolean processExternalEntities = false;
 
+	@Nullable
+	private volatile SAXParserFactory schemaParserFactory;
+
+	@Nullable
+	private volatile SAXParserFactory sourceParserFactory;
+
 
 	/**
 	 * Set multiple JAXB context paths. The given array of context paths gets
@@ -426,6 +434,7 @@ public void setMappedClass(Class<?> mappedClass) {
 	 */
 	public void setSupportDtd(boolean supportDtd) {
 		this.supportDtd = supportDtd;
+		this.sourceParserFactory = null;
 	}
 
 	/**
@@ -450,6 +459,7 @@ public void setProcessExternalEntities(boolean processExternalEntities) {
 		if (processExternalEntities) {
 			this.supportDtd = true;
 		}
+		this.sourceParserFactory = null;
 	}
 
 	/**
@@ -497,7 +507,9 @@ public JAXBContext getJaxbContext() {
 		if (context != null) {
 			return context;
 		}
-		synchronized (this.jaxbContextMonitor) {
+
+		this.jaxbContextLock.lock();
+		try {
 			context = this.jaxbContext;
 			if (context == null) {
 				try {
@@ -521,6 +533,9 @@ else if (!ObjectUtils.isEmpty(this.packagesToScan)) {
 			}
 			return context;
 		}
+		finally {
+			this.jaxbContextLock.unlock();
+		}
 	}
 
 	private JAXBContext createJaxbContextFromContextPath(String contextPath) throws JAXBException {
@@ -587,17 +602,24 @@ private Schema loadSchema(Resource[] resources, String schemaLanguage) throws IO
 		Assert.notEmpty(resources, "No resources given");
 		Assert.hasLength(schemaLanguage, "No schema language provided");
 		Source[] schemaSources = new Source[resources.length];
-		SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
-		saxParserFactory.setNamespaceAware(true);
-		saxParserFactory.setFeature("http://xml.org/sax/features/namespace-prefixes", true);
+
+		SAXParserFactory saxParserFactory = this.schemaParserFactory;
+		if (saxParserFactory == null) {
+			saxParserFactory = SAXParserFactory.newInstance();
+			saxParserFactory.setNamespaceAware(true);
+			saxParserFactory.setFeature("http://xml.org/sax/features/namespace-prefixes", true);
+			this.schemaParserFactory = saxParserFactory;
+		}
 		SAXParser saxParser = saxParserFactory.newSAXParser();
 		XMLReader xmlReader = saxParser.getXMLReader();
+
 		for (int i = 0; i < resources.length; i++) {
 			Resource resource = resources[i];
 			Assert.isTrue(resource != null && resource.exists(), () -> "Resource does not exist: " + resource);
 			InputSource inputSource = SaxResourceUtils.createInputSource(resource);
 			schemaSources[i] = new SAXSource(xmlReader, inputSource);
 		}
+
 		SchemaFactory schemaFactory = SchemaFactory.newInstance(schemaLanguage);
 		if (this.schemaResourceResolver != null) {
 			schemaFactory.setResourceResolver(this.schemaResourceResolver);
@@ -886,11 +908,16 @@ else if (streamSource.getReader() != null) {
 
 		try {
 			if (xmlReader == null) {
-				SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
-				saxParserFactory.setNamespaceAware(true);
-				saxParserFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());
-				String name = "http://xml.org/sax/features/external-general-entities";
-				saxParserFactory.setFeature(name, isProcessExternalEntities());
+				SAXParserFactory saxParserFactory = this.sourceParserFactory;
+				if (saxParserFactory == null) {
+					saxParserFactory = SAXParserFactory.newInstance();
+					saxParserFactory.setNamespaceAware(true);
+					saxParserFactory.setFeature(
+							"http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());
+					saxParserFactory.setFeature(
+							"http://xml.org/sax/features/external-general-entities", isProcessExternalEntities());
+					this.sourceParserFactory = saxParserFactory;
+				}
 				SAXParser saxParser = saxParserFactory.newSAXParser();
 				xmlReader = saxParser.getXMLReader();
 			}

spring-oxm/src/main/java/org/springframework/oxm/support/AbstractMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -83,9 +83,10 @@ public abstract class AbstractMarshaller implements Marshaller, Unmarshaller {
 	private boolean processExternalEntities = false;
 
 	@Nullable
-	private DocumentBuilderFactory documentBuilderFactory;
+	private volatile DocumentBuilderFactory documentBuilderFactory;
 
-	private final Object documentBuilderFactoryMonitor = new Object();
+	@Nullable
+	private volatile SAXParserFactory saxParserFactory;
 
 
 	/**
@@ -94,6 +95,8 @@ public abstract class AbstractMarshaller implements Marshaller, Unmarshaller {
 	 */
 	public void setSupportDtd(boolean supportDtd) {
 		this.supportDtd = supportDtd;
+		this.documentBuilderFactory = null;
+		this.saxParserFactory = null;
 	}
 
 	/**
@@ -118,6 +121,8 @@ public void setProcessExternalEntities(boolean processExternalEntities) {
 		if (processExternalEntities) {
 			this.supportDtd = true;
 		}
+		this.documentBuilderFactory = null;
+		this.saxParserFactory = null;
 	}
 
 	/**
@@ -137,14 +142,13 @@ public boolean isProcessExternalEntities() {
 	 */
 	protected Document buildDocument() {
 		try {
-			DocumentBuilder documentBuilder;
-			synchronized (this.documentBuilderFactoryMonitor) {
-				if (this.documentBuilderFactory == null) {
-					this.documentBuilderFactory = createDocumentBuilderFactory();
-				}
-				documentBuilder = createDocumentBuilder(this.documentBuilderFactory);
+			DocumentBuilderFactory builderFactory = this.documentBuilderFactory;
+			if (builderFactory == null) {
+				builderFactory = createDocumentBuilderFactory();
+				this.documentBuilderFactory = builderFactory;
 			}
-			return documentBuilder.newDocument();
+			DocumentBuilder builder = createDocumentBuilder(builderFactory);
+			return builder.newDocument();
 		}
 		catch (ParserConfigurationException ex) {
 			throw new UnmarshallingFailureException("Could not create document placeholder: " + ex.getMessage(), ex);
@@ -179,11 +183,11 @@ protected DocumentBuilderFactory createDocumentBuilderFactory() throws ParserCon
 	protected DocumentBuilder createDocumentBuilder(DocumentBuilderFactory factory)
 			throws ParserConfigurationException {
 
-		DocumentBuilder documentBuilder = factory.newDocumentBuilder();
+		DocumentBuilder builder = factory.newDocumentBuilder();
 		if (!isProcessExternalEntities()) {
-			documentBuilder.setEntityResolver(NO_OP_ENTITY_RESOLVER);
+			builder.setEntityResolver(NO_OP_ENTITY_RESOLVER);
 		}
-		return documentBuilder;
+		return builder;
 	}
 
 	/**
@@ -193,11 +197,17 @@ protected DocumentBuilder createDocumentBuilder(DocumentBuilderFactory factory)
 	 * @throws ParserConfigurationException if thrown by JAXP methods
 	 */
 	protected XMLReader createXmlReader() throws SAXException, ParserConfigurationException {
-		SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
-		saxParserFactory.setNamespaceAware(true);
-		saxParserFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());
-		saxParserFactory.setFeature("http://xml.org/sax/features/external-general-entities", isProcessExternalEntities());
-		SAXParser saxParser = saxParserFactory.newSAXParser();
+		SAXParserFactory parserFactory = this.saxParserFactory;
+		if (parserFactory == null) {
+			parserFactory = SAXParserFactory.newInstance();
+			parserFactory.setNamespaceAware(true);
+			parserFactory.setFeature(
+					"http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());
+			parserFactory.setFeature(
+					"http://xml.org/sax/features/external-general-entities", isProcessExternalEntities());
+			this.saxParserFactory = parserFactory;
+		}
+		SAXParser saxParser = parserFactory.newSAXParser();
 		XMLReader xmlReader = saxParser.getXMLReader();
 		if (!isProcessExternalEntities()) {
 			xmlReader.setEntityResolver(NO_OP_ENTITY_RESOLVER);

spring-web/src/main/java/org/springframework/http/converter/xml/Jaxb2RootElementHttpMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -61,6 +61,7 @@
  * @author Arjen Poutsma
  * @author Sebastien Deleuze
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  * @since 3.0
  * @see MarshallingHttpMessageConverter
  */
@@ -70,13 +71,17 @@ public class Jaxb2RootElementHttpMessageConverter extends AbstractJaxb2HttpMessa
 
 	private boolean processExternalEntities = false;
 
+	@Nullable
+	private volatile SAXParserFactory sourceParserFactory;
+
 
 	/**
 	 * Indicate whether DTD parsing should be supported.
 	 * <p>Default is {@code false} meaning that DTD is disabled.
 	 */
 	public void setSupportDtd(boolean supportDtd) {
 		this.supportDtd = supportDtd;
+		this.sourceParserFactory = null;
 	}
 
 	/**
@@ -97,6 +102,7 @@ public void setProcessExternalEntities(boolean processExternalEntities) {
 		if (processExternalEntities) {
 			this.supportDtd = true;
 		}
+		this.sourceParserFactory = null;
 	}
 
 	/**
@@ -156,11 +162,16 @@ protected Source processSource(Source source) {
 		if (source instanceof StreamSource streamSource) {
 			InputSource inputSource = new InputSource(streamSource.getInputStream());
 			try {
-				SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
-				saxParserFactory.setNamespaceAware(true);
-				saxParserFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());
-				String featureName = "http://xml.org/sax/features/external-general-entities";
-				saxParserFactory.setFeature(featureName, isProcessExternalEntities());
+				SAXParserFactory saxParserFactory = this.sourceParserFactory;
+				if (saxParserFactory == null) {
+					saxParserFactory = SAXParserFactory.newInstance();
+					saxParserFactory.setNamespaceAware(true);
+					saxParserFactory.setFeature(
+							"http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());
+					saxParserFactory.setFeature(
+							"http://xml.org/sax/features/external-general-entities", isProcessExternalEntities());
+					this.sourceParserFactory = saxParserFactory;
+				}
 				SAXParser saxParser = saxParserFactory.newSAXParser();
 				XMLReader xmlReader = saxParser.getXMLReader();
 				if (!isProcessExternalEntities()) {