Default to optimized launch of the JVM when using Gradle's bootRun

Closes gh-16222

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/running.adoc

@@ -8,11 +8,10 @@ To run your application without first building an archive use the `bootRun` task
 	$ ./gradlew bootRun
 ----
 
-The `bootRun` task is an instance of
-{boot-run-javadoc}[`BootRun`] which is a `JavaExec` subclass. As such, all of the
-{gradle-dsl}/org.gradle.api.tasks.JavaExec.html[usual configuration options] for executing
-a Java process in Gradle are available to you. The task is automatically configured to use
-the runtime classpath of the main source set.
+The `bootRun` task is an instance of {boot-run-javadoc}[`BootRun`] which is a `JavaExec`
+subclass. As such, all of the {gradle-dsl}/org.gradle.api.tasks.JavaExec.html[usual
+configuration options] for executing a Java process in Gradle are available to you. The
+task is automatically configured to use the runtime classpath of the main source set.
 
 By default, the main class will be configured automatically by looking for a class with a
 `public static void main(String[])` method in directories on the task's classpath.
@@ -48,6 +47,23 @@ include::../gradle/running/spring-boot-dsl-main-class-name.gradle.kts[tags=main-
 ----
 
 
+By default, `bootRun` will configure the JVM to optimize its launch for faster startup
+during development. This behavior can be disabled by using the `optimizedLaunch` property,
+as shown in the following example:
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/running/boot-run-disable-optimized-launch.gradle[tags=launch]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/running/boot-run-disable-optimized-launch.gradle.kts[tags=launch]
+----
+
+
 If the {application-plugin}[`application` plugin] has been applied, its `mainClassName`
 project property must be configured and can be used for the same purpose:
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/running/boot-run-disable-optimized-launch.gradle

+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+// tag::launch[]
+bootRun {
+	optimizedLaunch = false
+}
+// end::launch[]
+
+task optimizedLaunch {
+	doLast {
+		println bootRun.optimizedLaunch
+	}
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/running/boot-run-disable-optimized-launch.gradle.kts

+import org.springframework.boot.gradle.tasks.run.BootRun
+
+plugins {
+	java
+	id("org.springframework.boot") version "{version}"
+}
+
+// tag::launch[]
+tasks.getByName<BootRun>("bootRun") {
+	isOptimizedLaunch = false
+}
+// end::launch[]
+
+task("optimizedLaunch") {
+	doLast {
+		println(tasks.getByName<BootRun>("bootRun").isOptimizedLaunch)
+	}
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/run/BootRun.java

 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -17,6 +17,7 @@
 package org.springframework.boot.gradle.tasks.run;
 
 import org.gradle.api.file.SourceDirectorySet;
+import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.JavaExec;
 import org.gradle.api.tasks.SourceSet;
 import org.gradle.api.tasks.SourceSetOutput;
@@ -29,6 +30,29 @@ import org.gradle.api.tasks.SourceSetOutput;
  */
 public class BootRun extends JavaExec {
 
+	private boolean optimizedLaunch = true;
+
+	/**
+	 * Returns {@code true} if the JVM's launch should be optimized, otherwise
+	 * {@code false}. Defaults to {@code true}.
+	 * @return whether the JVM's launch should be optimized
+	 * @since 2.2.0
+	 */
+	@Input
+	public boolean isOptimizedLaunch() {
+		return this.optimizedLaunch;
+	}
+
+	/**
+	 * Sets whether the JVM's launch should be optimized. Defaults to {@code true}.
+	 * @param optimizedLaunch {@code true} if the JVM's launch should be optimised,
+	 * otherwise {@code false}
+	 * @since 2.2.0
+	 */
+	public void setOptimizedLaunch(boolean optimizedLaunch) {
+		this.optimizedLaunch = optimizedLaunch;
+	}
+
 	/**
 	 * Adds the {@link SourceDirectorySet#getSrcDirs() source directories} of the given
 	 * {@code sourceSet's} {@link SourceSet#getResources() resources} to the start of the
@@ -44,6 +68,10 @@ public class BootRun extends JavaExec {
 
 	@Override
 	public void exec() {
+		if (this.optimizedLaunch) {
+			setJvmArgs(getJvmArgs());
+			jvmArgs("-Xverify:none", "-XX:TieredStopAtLevel=1");
+		}
 		if (System.console() != null) {
 			// Record that the console is available here for AnsiOutput to detect later
 			this.getEnvironment().put("spring.output.ansi.console-available", true);

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/BootRunApplication.java → spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/classpath/BootRunClasspathApplication.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -14,19 +14,19 @@
  * limitations under the License.
  */
 
-package com.example;
+package com.example.classpath;
 
 import java.io.File;
 import java.lang.management.ManagementFactory;
 
 /**
- * Very basic application used for testing {@code BootRun}.
+ * Application used for testing {@code BootRun}'s classpath handling.
  *
  * @author Andy Wilkinson
  */
-public class BootRunApplication {
+public class BootRunClasspathApplication {
 
-	protected BootRunApplication() {
+	protected BootRunClasspathApplication() {
 
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/jvmargs/BootRunJvmArgsApplication.java

+/*
+ * Copyright 2012-2019 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 com.example.jvmargs;
+
+import java.lang.management.ManagementFactory;
+
+/**
+ * Application used for testing {@code BootRun}'s JVM argument handling.
+ *
+ * @author Andy Wilkinson
+ */
+public class BootRunJvmArgsApplication {
+
+	protected BootRunJvmArgsApplication() {
+
+	}
+
+	public static void main(String[] args) {
+		int i = 1;
+		for (String entry : ManagementFactory.getRuntimeMXBean().getInputArguments()) {
+			System.out.println(i++ + ". " + entry);
+		}
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/RunningDocumentationTests.java

@@ -69,4 +69,11 @@ public class RunningDocumentationTests {
 						.contains(new File("src/main/resources").getPath());
 	}
 
+	@TestTemplate
+	public void bootRunDisableOptimizedLaunch() throws IOException {
+		assertThat(this.gradleBuild
+				.script("src/main/gradle/running/boot-run-disable-optimized-launch")
+				.build("optimizedLaunch").getOutput()).contains("false");
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/run/BootRunIntegrationTests.java

@@ -42,7 +42,7 @@ public class BootRunIntegrationTests {
 
 	@TestTemplate
 	public void basicExecution() throws IOException {
-		copyApplication();
+		copyClasspathApplication();
 		new File(this.gradleBuild.getProjectDir(), "src/main/resources").mkdirs();
 		BuildResult result = this.gradleBuild.build("bootRun");
 		assertThat(result.task(":bootRun").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
@@ -56,7 +56,7 @@ public class BootRunIntegrationTests {
 
 	@TestTemplate
 	public void sourceResourcesCanBeUsed() throws IOException {
-		copyApplication();
+		copyClasspathApplication();
 		BuildResult result = this.gradleBuild.build("bootRun");
 		assertThat(result.task(":bootRun").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
 		assertThat(result.getOutput())
@@ -87,28 +87,56 @@ public class BootRunIntegrationTests {
 
 	@TestTemplate
 	public void applicationPluginMainClassNameIsNotUsedWhenItIsNull() throws IOException {
-		copyApplication();
+		copyClasspathApplication();
 		BuildResult result = this.gradleBuild.build("echoMainClassName");
 		assertThat(result.task(":echoMainClassName").getOutcome())
 				.isEqualTo(TaskOutcome.SUCCESS);
-		assertThat(result.getOutput())
-				.contains("Main class name = com.example.BootRunApplication");
+		assertThat(result.getOutput()).contains(
+				"Main class name = com.example.classpath.BootRunClasspathApplication");
+	}
+
+	@TestTemplate
+	public void defaultJvmArgs() throws IOException {
+		copyJvmArgsApplication();
+		BuildResult result = this.gradleBuild.build("bootRun");
+		assertThat(result.task(":bootRun").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).contains("1. -Xverify:none")
+				.contains("2. -XX:TieredStopAtLevel=1");
+	}
+
+	@TestTemplate
+	public void optimizedLaunchDisabledJvmArgs() throws IOException {
+		copyJvmArgsApplication();
+		BuildResult result = this.gradleBuild.build("bootRun");
+		assertThat(result.task(":bootRun").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).doesNotContain("-Xverify:none")
+				.doesNotContain("-XX:TieredStopAtLevel=1");
 	}
 
 	@TestTemplate
 	public void applicationPluginJvmArgumentsAreUsed() throws IOException {
-		BuildResult result = this.gradleBuild.build("echoJvmArguments");
-		assertThat(result.task(":echoJvmArguments").getOutcome())
-				.isEqualTo(TaskOutcome.UP_TO_DATE);
-		assertThat(result.getOutput())
-				.contains("JVM arguments = [-Dcom.foo=bar, -Dcom.bar=baz]");
+		copyJvmArgsApplication();
+		BuildResult result = this.gradleBuild.build("bootRun");
+		assertThat(result.task(":bootRun").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).contains("1. -Dcom.bar=baz")
+				.contains("2. -Dcom.foo=bar").contains("3. -Xverify:none")
+				.contains("4. -XX:TieredStopAtLevel=1");
+	}
+
+	private void copyClasspathApplication() throws IOException {
+		copyApplication("classpath");
+	}
+
+	private void copyJvmArgsApplication() throws IOException {
+		copyApplication("jvmargs");
 	}
 
-	private void copyApplication() throws IOException {
+	private void copyApplication(String name) throws IOException {
 		File output = new File(this.gradleBuild.getProjectDir(),
-				"src/main/java/com/example");
+				"src/main/java/com/example/" + name);
 		output.mkdirs();
-		FileSystemUtils.copyRecursively(new File("src/test/java/com/example"), output);
+		FileSystemUtils.copyRecursively(new File("src/test/java/com/example/" + name),
+				output);
 	}
 
 	private String canonicalPathOf(String path) throws IOException {

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/run/BootRunIntegrationTests-applicationPluginJvmArgumentsAreUsed.gradle

@@ -4,7 +4,3 @@ plugins {
 }
 
 applicationDefaultJvmArgs = ['-Dcom.foo=bar', '-Dcom.bar=baz']
-
-task echoJvmArguments {
-	println 'JVM arguments = ' + bootRun.jvmArgs
-}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/run/BootRunIntegrationTests-defaultJvmArgs.gradle

+plugins {
+	id 'application'
+	id 'org.springframework.boot' version '{version}'
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/run/BootRunIntegrationTests-optimizedLaunchDisabledJvmArgs.gradle

+plugins {
+	id 'application'
+	id 'org.springframework.boot' version '{version}'
+}
+
+bootRun {
+	optimizedLaunch = false
+}