Open DefaultLifecycleProcessor for extension

Includes a demonstration ConcurrentLifecycleProcessor class

As per spring-projectsgh-34634

Author: fralalonde

spring-context/src/main/java/org/springframework/context/support/ConcurrentLifecycleProcessor.java

@@ -0,0 +1,91 @@
+package org.springframework.context.support;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.context.Lifecycle;
+
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.concurrent.*;
+
+/**
+ * An example extension of Spring's {@link DefaultLifecycleProcessor}.
+ * </p>
+ * All Lifecycle beans of a same phase start _at once_ rather than sequentially.
+ * Phases still only complete after every bean has returned from start().
+ * </p>
+ * A start timeout can be specified for each phase; the default timeout is 10 seconds.
+ * If any timeout is exceeded, an exception is thrown and the application context refresh() fails.
+ * </p>
+ * @author Francis Lalonde
+ */
+public class ConcurrentLifecycleProcessor extends DefaultLifecycleProcessor {
+
+	private final Map<Integer, Long> timeoutsForStartPhases = new ConcurrentHashMap<>();
+
+	private final long timeoutPerStartPhase = 10000;
+
+	public void setTimeoutsForStartPhases(Map<Integer, Long> timeoutsForShutdownPhases) {
+		this.timeoutsForStartPhases.putAll(timeoutsForShutdownPhases);
+	}
+
+	protected long determineStartTimeout(int phase) {
+		Long timeout = this.timeoutsForStartPhases.get(phase);
+		return (timeout != null ? timeout : this.timeoutPerStartPhase);
+	}
+
+	@Override
+	protected void startBeans(boolean autoStartupOnly) {
+		Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans();
+		Map<Integer, ConcurentLifecycleGroup> phases = new TreeMap<>();
+
+		lifecycleBeans.forEach((beanName, bean) -> {
+			if (!autoStartupOnly || isAutoStartupCandidate(beanName, bean)) {
+				int startupPhase = getPhase(bean);
+				phases.computeIfAbsent(startupPhase,
+						phase -> new ConcurentLifecycleGroup(phase, determineStartTimeout(phase), determineStopTimeout(phase), lifecycleBeans, autoStartupOnly)
+				).add(beanName, bean);
+			}
+		});
+
+		if (!phases.isEmpty()) {
+			phases.values().forEach(ConcurentLifecycleGroup::start);
+		}
+	}
+
+	protected class ConcurentLifecycleGroup extends LifecycleGroup {
+
+		private final Log logger = LogFactory.getLog(getClass());
+
+		private final long startTimeout;
+
+		public ConcurentLifecycleGroup(int phase, long startTimeout, long stopTimeout, Map<String, ? extends Lifecycle> lifecycleBeans, boolean autoStartupOnly) {
+			super(phase, stopTimeout, lifecycleBeans, autoStartupOnly);
+			this.startTimeout = startTimeout;
+		}
+
+		@Override
+		public void start() {
+			if (this.members.isEmpty()) {
+				return;
+			}
+			if (logger.isDebugEnabled()) {
+				logger.debug("Starting beans in phase " + phase);
+			}
+
+			List<CompletableFuture<Void>> starting = members.stream()
+					.map(member -> CompletableFuture.runAsync(() -> doStart(lifecycleBeans, member.name(), autoStartupOnly)))
+					.toList();
+
+			try {
+				CompletableFuture.allOf(starting.toArray(CompletableFuture<?>[]::new))
+						.get(startTimeout, TimeUnit.MILLISECONDS);
+			} catch (TimeoutException e) {
+				throw new IllegalStateException("Timeout exceeded starting beans in phase " + this.phase, e);
+			} catch (InterruptedException | ExecutionException e) {
+				throw new IllegalStateException("Error starting beans in phase " + this.phase, e);
+			}
+		}
+	}
+}

spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java

@@ -168,7 +168,7 @@ public void setTimeoutPerShutdownPhase(long timeoutPerShutdownPhase) {
 		this.timeoutPerShutdownPhase = timeoutPerShutdownPhase;
 	}
 
-	private long determineTimeout(int phase) {
+	protected long determineStopTimeout(int phase) {
 		Long timeout = this.timeoutsForShutdownPhases.get(phase);
 		return (timeout != null ? timeout : this.timeoutPerShutdownPhase);
 	}
@@ -182,7 +182,7 @@ public void setBeanFactory(BeanFactory beanFactory) {
 		this.beanFactory = clbf;
 	}
 
-	private ConfigurableListableBeanFactory getBeanFactory() {
+	protected ConfigurableListableBeanFactory getBeanFactory() {
 		ConfigurableListableBeanFactory beanFactory = this.beanFactory;
 		Assert.state(beanFactory != null, "No BeanFactory available");
 		return beanFactory;
@@ -275,15 +275,15 @@ void restartAfterStop() {
 		}
 	}
 
-	private void startBeans(boolean autoStartupOnly) {
+	protected void startBeans(boolean autoStartupOnly) {
 		Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans();
 		Map<Integer, LifecycleGroup> phases = new TreeMap<>();
 
 		lifecycleBeans.forEach((beanName, bean) -> {
 			if (!autoStartupOnly || isAutoStartupCandidate(beanName, bean)) {
 				int startupPhase = getPhase(bean);
 				phases.computeIfAbsent(startupPhase,
-						phase -> new LifecycleGroup(phase, determineTimeout(phase), lifecycleBeans, autoStartupOnly)
+						phase -> new LifecycleGroup(phase, determineStopTimeout(phase), lifecycleBeans, autoStartupOnly)
 				).add(beanName, bean);
 			}
 		});
@@ -293,7 +293,7 @@ private void startBeans(boolean autoStartupOnly) {
 		}
 	}
 
-	private boolean isAutoStartupCandidate(String beanName, Lifecycle bean) {
+	protected boolean isAutoStartupCandidate(String beanName, Lifecycle bean) {
 		Set<String> stoppedBeans = this.stoppedBeans;
 		return (stoppedBeans != null ? stoppedBeans.contains(beanName) :
 				(bean instanceof SmartLifecycle smartLifecycle && smartLifecycle.isAutoStartup()));
@@ -305,7 +305,7 @@ private boolean isAutoStartupCandidate(String beanName, Lifecycle bean) {
 	 * @param lifecycleBeans a Map with bean name as key and Lifecycle instance as value
 	 * @param beanName the name of the bean to start
 	 */
-	private void doStart(Map<String, ? extends Lifecycle> lifecycleBeans, String beanName, boolean autoStartupOnly) {
+	protected void doStart(Map<String, ? extends Lifecycle> lifecycleBeans, String beanName, boolean autoStartupOnly) {
 		Lifecycle bean = lifecycleBeans.remove(beanName);
 		if (bean != null && bean != this) {
 			String[] dependenciesForBean = getBeanFactory().getDependenciesForBean(beanName);
@@ -342,7 +342,7 @@ private void stopBeans() {
 		lifecycleBeans.forEach((beanName, bean) -> {
 			int shutdownPhase = getPhase(bean);
 			phases.computeIfAbsent(shutdownPhase,
-					phase -> new LifecycleGroup(phase, determineTimeout(phase), lifecycleBeans, false)
+					phase -> new LifecycleGroup(phase, determineStopTimeout(phase), lifecycleBeans, false)
 			).add(beanName, bean);
 		});
 
@@ -357,7 +357,7 @@ private void stopBeans() {
 	 * @param lifecycleBeans a Map with bean name as key and Lifecycle instance as value
 	 * @param beanName the name of the bean to stop
 	 */
-	private void doStop(Map<String, ? extends Lifecycle> lifecycleBeans, final String beanName,
+	protected void doStop(Map<String, ? extends Lifecycle> lifecycleBeans, final String beanName,
 			final CountDownLatch latch, final Set<String> countDownBeanNames) {
 
 		Lifecycle bean = lifecycleBeans.remove(beanName);
@@ -466,17 +466,17 @@ protected int getPhase(Lifecycle bean) {
 	 * The group is expected to be created in an ad-hoc fashion and group members are
 	 * expected to always have the same 'phase' value.
 	 */
-	private class LifecycleGroup {
+	protected class LifecycleGroup {
 
-		private final int phase;
+		protected final int phase;
 
-		private final long timeout;
+		protected final long timeout;
 
-		private final Map<String, ? extends Lifecycle> lifecycleBeans;
+		protected final Map<String, ? extends Lifecycle> lifecycleBeans;
 
-		private final boolean autoStartupOnly;
+		protected final boolean autoStartupOnly;
 
-		private final List<LifecycleGroupMember> members = new ArrayList<>();
+		protected final List<LifecycleGroupMember> members = new ArrayList<>();
 
 		private int smartMemberCount;
 
@@ -545,7 +545,7 @@ else if (member.bean instanceof SmartLifecycle) {
 	/**
 	 * A simple record of a LifecycleGroup member.
 	 */
-	private record LifecycleGroupMember(String name, Lifecycle bean) {}
+	protected record LifecycleGroupMember(String name, Lifecycle bean) {}
 
 
 	/**