Merge pull request #50779 from dhruv-15-03

* fix-jul-bridge-uninstall-asymmetry:
  Polish "Avoid removing application-managed JUL bridge handler"
  Avoid removing application-managed JUL bridge handler

Closes gh-50779

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystem.java

@@ -76,6 +76,7 @@ import org.springframework.util.StringUtils;
  * @author Ben Hale
  * @author Ralph Goers
  * @author Piotr P. Karwasz
+ * @author Dhruv Rastogi
  * @since 1.2.0
  */
 public class Log4J2LoggingSystem extends AbstractLoggingSystem {
@@ -118,6 +119,8 @@ public class Log4J2LoggingSystem extends AbstractLoggingSystem {
 
 	private final LoggerContext loggerContext;
 
+	private boolean bridgeHandlerInstalled;
+
 	/**
 	 * Create a new {@link Log4J2LoggingSystem} instance.
 	 * @param classLoader the class loader to use.
@@ -189,6 +192,7 @@ public class Log4J2LoggingSystem extends AbstractLoggingSystem {
 					&& isLog4jBridgeHandlerAvailable()) {
 				removeDefaultRootHandler();
 				Log4jBridgeHandler.install(false, null, true);
+				this.bridgeHandlerInstalled = true;
 				return true;
 			}
 		}
@@ -454,8 +458,9 @@ public class Log4J2LoggingSystem extends AbstractLoggingSystem {
 
 	@Override
 	public void cleanUp() {
-		if (isLog4jBridgeHandlerAvailable()) {
+		if (this.bridgeHandlerInstalled) {
 			removeLog4jBridgeHandler();
+			this.bridgeHandlerInstalled = false;
 		}
 		super.cleanUp();
 		LoggerContext loggerContext = getLoggerContext();

core/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystem.java

@@ -75,6 +75,7 @@ import org.springframework.util.StringUtils;
  * @author Dave Syer
  * @author Andy Wilkinson
  * @author Ben Hale
+ * @author Dhruv Rastogi
  * @since 1.0.0
  */
 public class LogbackLoggingSystem extends AbstractLoggingSystem implements BeanFactoryInitializationAotProcessor {
@@ -111,6 +112,8 @@ public class LogbackLoggingSystem extends AbstractLoggingSystem implements BeanF
 
 	private final StatusPrinter2 statusPrinter = new StatusPrinter2();
 
+	private boolean bridgeHandlerInstalled;
+
 	public LogbackLoggingSystem(ClassLoader classLoader) {
 		super(classLoader);
 	}
@@ -141,6 +144,7 @@ public class LogbackLoggingSystem extends AbstractLoggingSystem implements BeanF
 			if (isBridgeJulIntoSlf4j()) {
 				removeJdkLoggingBridgeHandler();
 				SLF4JBridgeHandler.install();
+				this.bridgeHandlerInstalled = true;
 			}
 		}
 		catch (Throwable ex) {
@@ -334,8 +338,9 @@ public class LogbackLoggingSystem extends AbstractLoggingSystem implements BeanF
 		LoggerContext context = getLoggerContext();
 		markAsUninitialized(context);
 		super.cleanUp();
-		if (isBridgeHandlerAvailable()) {
+		if (this.bridgeHandlerInstalled) {
 			removeJdkLoggingBridgeHandler();
+			this.bridgeHandlerInstalled = false;
 		}
 		context.getStatusManager().clear();
 		context.getTurboFilterList().remove(SUPPRESS_ALL_FILTER);

core/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystemTests.java

@@ -88,6 +88,7 @@ import static org.mockito.Mockito.times;
  * @author Ben Hale
  * @author Madhura Bhave
  * @author Piotr P. Karwasz
+ * @author Dhruv Rastogi
  */
 @ExtendWith(OutputCaptureExtension.class)
 @ClassPathExclusions("logback-*.jar")
@@ -406,6 +407,35 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 		assertThat(logger.getLevel()).isEqualTo(Level.FINE);
 	}
 
+	@Test
+	void cleanUpCleansBridgeHandlerInstalledByTheLoggingSystem() {
+		this.loggingSystem.beforeInitialize();
+		java.util.logging.Logger rootLogger = java.util.logging.Logger.getLogger("");
+		assertThat(rootLogger.getHandlers()).hasAtLeastOneElementOfType(Log4jBridgeHandler.class);
+		this.loggingSystem.cleanUp();
+		java.util.logging.Logger rootLoggerAfterCleanUp = java.util.logging.Logger.getLogger("");
+		assertThat(rootLoggerAfterCleanUp.getHandlers()).doesNotHaveAnyElementsOfTypes(Log4jBridgeHandler.class);
+	}
+
+	@Test
+	void cleanUpLeavesBridgeHandlerInstalledByTheApplicationInPlace() {
+		java.util.logging.Logger rootLogger = java.util.logging.Logger.getLogger("");
+		Log4jBridgeHandler.install(false, null, true);
+		try {
+			assertThat(rootLogger.getHandlers()).hasAtLeastOneElementOfType(Log4jBridgeHandler.class);
+			this.loggingSystem.beforeInitialize();
+			this.loggingSystem.cleanUp();
+			assertThat(rootLogger.getHandlers()).hasAtLeastOneElementOfType(Log4jBridgeHandler.class);
+		}
+		finally {
+			for (Handler handler : rootLogger.getHandlers()) {
+				if (handler instanceof Log4jBridgeHandler) {
+					rootLogger.removeHandler(handler);
+				}
+			}
+		}
+	}
+
 	@Test
 	void shutdownHookIsDisabled() {
 		assertThat(

core/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

@@ -107,6 +107,7 @@ import static org.mockito.Mockito.times;
  * @author Scott Frederick
  * @author Jonatan Ivanov
  * @author Moritz Halbritter
+ * @author Dhruv Rastogi
  */
 @ExtendWith(OutputCaptureExtension.class)
 @ClassPathExclusions({ "log4j-core-*.jar", "log4j-api-*.jar" })
@@ -340,6 +341,20 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 		assertThat(bridgeHandlerInstalled()).isFalse();
 	}
 
+	@Test
+	void cleanUpLeavesBridgeHandlerInstalledByTheApplicationInPlace() {
+		SLF4JBridgeHandler.install();
+		try {
+			assertThat(bridgeHandlerInstalled()).isTrue();
+			this.loggingSystem.beforeInitialize();
+			this.loggingSystem.cleanUp();
+			assertThat(bridgeHandlerInstalled()).isTrue();
+		}
+		finally {
+			SLF4JBridgeHandler.uninstall();
+		}
+	}
+
 	@Test
 	void standardConfigLocations() {
 		String[] locations = this.loggingSystem.getStandardConfigLocations();