Stop interactive shell runner on context close

czpilar · fmbenhassine · commit 7cfedb232d2f · 2026-06-05T11:13:12.000+02:00
Reuse JLine terminal across context restarts Resolves #1224 Signed-off-by: David Pilar <david@czpilar.net>
diff --git a/spring-shell-core-autoconfigure/src/main/java/org/springframework/shell/core/autoconfigure/JLineShellAutoConfiguration.java b/spring-shell-core-autoconfigure/src/main/java/org/springframework/shell/core/autoconfigure/JLineShellAutoConfiguration.java
@@ -79,6 +79,11 @@ public class JLineShellAutoConfiguration {
 
 	private final static Log log = LogFactory.getLog(JLineShellAutoConfiguration.class);
 
+	// Reused across context restarts (e.g. DevTools) to keep one reader of stdin.
+	private static volatile Terminal sharedTerminal;
+
+	private static final Object sharedTerminalLock = new Object();
+
 	private org.jline.reader.History jLineHistory;
 
 	@Value("${spring.application.name:spring-shell}.log")
@@ -158,16 +163,40 @@ public JLineInputProvider inputProvider(LineReader lineReader, PromptProvider pr
 		return inputProvider;
 	}
 
-	@Bean(destroyMethod = "close")
+	// Not closed on context close (shared); closed on JVM shutdown instead.
+	@Bean(destroyMethod = "")
 	public Terminal terminal(ObjectProvider<TerminalCustomizer> customizers) {
+		Terminal terminal = sharedTerminal;
+		if (terminal != null) {
+			return terminal;
+		}
+		synchronized (sharedTerminalLock) {
+			if (sharedTerminal == null) {
+				try {
+					TerminalBuilder builder = TerminalBuilder.builder();
+					builder.systemOutput(SystemOutput.SysOut);
+					customizers.orderedStream().forEach(customizer -> customizer.customize(builder));
+					Terminal built = builder.build();
+					Runtime.getRuntime()
+						.addShutdownHook(new Thread(() -> closeTerminal(built), "spring-shell-terminal-close"));
+					sharedTerminal = built;
+				}
+				catch (IOException e) {
+					throw new BeanCreationException("Could not create Terminal", e);
+				}
+			}
+			return sharedTerminal;
+		}
+	}
+
+	private static void closeTerminal(Terminal terminal) {
 		try {
-			TerminalBuilder builder = TerminalBuilder.builder();
-			builder.systemOutput(SystemOutput.SysOut);
-			customizers.orderedStream().forEach(customizer -> customizer.customize(builder));
-			return builder.build();
+			terminal.close();
 		}
-		catch (IOException e) {
-			throw new BeanCreationException("Could not create Terminal", e);
+		catch (IOException ex) {
+			if (log.isDebugEnabled()) {
+				log.debug("Failed to close terminal on shutdown", ex);
+			}
 		}
 	}
 
diff --git a/spring-shell-core-autoconfigure/src/test/java/org/springframework/shell/core/autoconfigure/JLineShellAutoConfigurationTests.java b/spring-shell-core-autoconfigure/src/test/java/org/springframework/shell/core/autoconfigure/JLineShellAutoConfigurationTests.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2025-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.core.autoconfigure;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.jline.terminal.Terminal;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.shell.core.command.annotation.Command;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+/**
+ * @author David Pilar
+ */
+class JLineShellAutoConfigurationTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withUserConfiguration(SpringShellApplication.class)
+		.withConfiguration(AutoConfigurations.of(SpringShellAutoConfiguration.class))
+		.withPropertyValues("spring.shell.interactive.enabled=false");
+
+	@Test
+	void terminalIsReusedAcrossContextsAndSurvivesContextClose() {
+		AtomicReference<Terminal> firstTerminal = new AtomicReference<>();
+		this.contextRunner.run(context -> firstTerminal.set(context.getBean(Terminal.class)));
+
+		// First context is closed; the shared terminal must survive so a restart reuses
+		// it.
+		this.contextRunner.run(context -> {
+			Terminal terminal = context.getBean(Terminal.class);
+			assertSame(firstTerminal.get(), terminal);
+			// getAttributes() throws if the terminal has been closed
+			assertDoesNotThrow(terminal::getAttributes);
+		});
+	}
+
+	@SpringBootApplication
+	static class SpringShellApplication {
+
+		@Command
+		void hi() {
+			System.out.println("Hello world!");
+		}
+
+	}
+
+}
diff --git a/spring-shell-core/src/main/java/org/springframework/shell/core/InteractiveShellRunner.java b/spring-shell-core/src/main/java/org/springframework/shell/core/InteractiveShellRunner.java
@@ -20,6 +20,7 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.beans.factory.DisposableBean;
 import org.springframework.shell.core.command.CommandContext;
 import org.springframework.shell.core.command.CommandExecutionException;
 import org.springframework.shell.core.command.CommandExecutor;
@@ -35,12 +36,15 @@
  * to print messages and flush the output.
  *
  * @author Mahmoud Ben Hassine
+ * @author David Pilar
  * @since 4.0.0
  */
-public abstract class InteractiveShellRunner implements ShellRunner {
+public abstract class InteractiveShellRunner implements ShellRunner, DisposableBean {
 
 	private static final Log log = LogFactory.getLog(InteractiveShellRunner.class);
 
+	private static final long STOP_JOIN_TIMEOUT_MS = 2000L;
+
 	private final CommandParser commandParser;
 
 	private final CommandExecutor commandExecutor;
@@ -51,6 +55,10 @@ public abstract class InteractiveShellRunner implements ShellRunner {
 
 	private boolean debugMode = false;
 
+	private volatile boolean running = true;
+
+	private volatile Thread runnerThread;
+
 	/**
 	 * Create a new {@link InteractiveShellRunner} instance.
 	 * @param inputProvider the input provider
@@ -70,7 +78,17 @@ public void run(String[] args) throws Exception {
 		if (args.length != 0) {
 			log.warn("Running in interactive mode, arguments will be ignored");
 		}
-		while (true) {
+		this.runnerThread = Thread.currentThread();
+		try {
+			doRun();
+		}
+		finally {
+			this.runnerThread = null;
+		}
+	}
+
+	private void doRun() {
+		while (this.running) {
 			String input;
 			try {
 				input = this.inputProvider.readInput();
@@ -84,7 +102,7 @@ public void run(String[] args) throws Exception {
 				}
 			}
 			catch (Exception e) {
-				if (this.debugMode) {
+				if (this.running && this.debugMode) {
 					e.printStackTrace();
 				}
 				break;
@@ -169,4 +187,42 @@ public void setDebugMode(boolean debugMode) {
 		this.debugMode = debugMode;
 	}
 
+	/**
+	 * Signal the runner to stop and wait briefly for its thread to exit.
+	 */
+	public void stop() {
+		if (!this.running) {
+			return;
+		}
+		this.running = false;
+		try {
+			wakeup();
+		}
+		catch (Exception ex) {
+			if (log.isDebugEnabled()) {
+				log.debug("Failed to wake up shell runner", ex);
+			}
+		}
+		Thread thread = this.runnerThread;
+		if (thread != null && thread != Thread.currentThread()) {
+			try {
+				thread.join(STOP_JOIN_TIMEOUT_MS);
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+			}
+		}
+	}
+
+	/**
+	 * Unblock a parked {@link InputProvider#readInput()} so {@link #stop()} can return.
+	 */
+	protected void wakeup() {
+	}
+
+	@Override
+	public void destroy() {
+		stop();
+	}
+
 }
diff --git a/spring-shell-jline/src/main/java/org/springframework/shell/jline/JLineShellRunner.java b/spring-shell-jline/src/main/java/org/springframework/shell/jline/JLineShellRunner.java
@@ -18,7 +18,10 @@
 import java.io.Console;
 import java.io.PrintWriter;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.jline.reader.LineReader;
+import org.jline.terminal.Terminal;
 
 import org.springframework.shell.core.InputReader;
 import org.springframework.shell.core.InteractiveShellRunner;
@@ -29,10 +32,13 @@
  * Interactive shell runner based on the JVM's system {@link Console}.
  *
  * @author Mahmoud Ben Hassine
+ * @author David Pilar
  * @since 4.0.0
  */
 public class JLineShellRunner extends InteractiveShellRunner {
 
+	private static final Log log = LogFactory.getLog(JLineShellRunner.class);
+
 	private final LineReader lineReader;
 
 	/**
@@ -67,4 +73,20 @@ public InputReader getReader() {
 		return new JLineInputReader(this.lineReader);
 	}
 
+	/**
+	 * Raise {@code INT} on the terminal so the blocked {@link LineReader#readLine()}
+	 * throws.
+	 */
+	@Override
+	protected void wakeup() {
+		try {
+			this.lineReader.getTerminal().raise(Terminal.Signal.INT);
+		}
+		catch (Exception ex) {
+			if (log.isDebugEnabled()) {
+				log.debug("Failed to raise INT on terminal to wake up line reader", ex);
+			}
+		}
+	}
+
 }
