From 53ce37ad29b4fe83a5e73a4fd685348e8d13e762 Mon Sep 17 00:00:00 2001 From: Steve Loughran Date: Mon, 20 Aug 2018 19:18:37 -0700 Subject: [PATCH] HADOOP-15679. ShutdownHookManager shutdown time needs to be configurable & extended. Contributed by Steve Loughran. Change-Id: Ifd4a6e3f796b4dc88e97f63066289e2534c77a29 (cherry picked from commit 95fcdc04355920697337db1136ffe463d4794616) --- .../fs/CommonConfigurationKeysPublic.java | 9 + .../hadoop/util/ShutdownHookManager.java | 169 +++++++-- .../src/main/resources/core-default.xml | 16 + .../hadoop/util/TestShutdownHookManager.java | 326 ++++++++++++++---- 4 files changed, 417 insertions(+), 103 deletions(-) diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeysPublic.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeysPublic.java index 63803c993c6..30d2f31a121 100644 --- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeysPublic.java +++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeysPublic.java @@ -888,5 +888,14 @@ public class CommonConfigurationKeysPublic { "credential$", "oauth.*token$", HADOOP_SECURITY_SENSITIVE_CONFIG_KEYS); + + /** Configuration option for the shutdown hook manager shutdown time: + * {@value}. */ + public static final String SERVICE_SHUTDOWN_TIMEOUT = + "hadoop.service.shutdown.timeout"; + + /** Default shutdown hook timeout: {@value} seconds. */ + public static final long SERVICE_SHUTDOWN_TIMEOUT_DEFAULT = 30; + } diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ShutdownHookManager.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ShutdownHookManager.java index 153f92b825e..2ca8e55f0bd 100644 --- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ShutdownHookManager.java +++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ShutdownHookManager.java @@ -17,11 +17,17 @@ */ package org.apache.hadoop.util; +import com.google.common.annotations.VisibleForTesting; import com.google.common.util.concurrent.ThreadFactoryBuilder; import org.apache.hadoop.util.concurrent.HadoopExecutors; import org.slf4j.Logger; import org.slf4j.LoggerFactory; +import org.apache.hadoop.classification.InterfaceAudience; +import org.apache.hadoop.classification.InterfaceStability; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.fs.CommonConfigurationKeysPublic; + import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; @@ -34,6 +40,9 @@ import java.util.concurrent.TimeoutException; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicBoolean; +import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.SERVICE_SHUTDOWN_TIMEOUT; +import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.SERVICE_SHUTDOWN_TIMEOUT_DEFAULT; + /** * The ShutdownHookManager enables running shutdownHook * in a deterministic order, higher priority first. @@ -42,53 +51,55 @@ import java.util.concurrent.atomic.AtomicBoolean; * This class registers a single JVM shutdownHook and run all the * shutdownHooks registered to it (to this class) in order based on their * priority. + * + * Unless a hook was registered with a shutdown explicitly set through + * {@link #addShutdownHook(Runnable, int, long, TimeUnit)}, + * the shutdown time allocated to it is set by the configuration option + * {@link CommonConfigurationKeysPublic#SERVICE_SHUTDOWN_TIMEOUT} in + * {@code core-site.xml}, with a default value of + * {@link CommonConfigurationKeysPublic#SERVICE_SHUTDOWN_TIMEOUT_DEFAULT} + * seconds. */ -public class ShutdownHookManager { +@InterfaceAudience.Public +@InterfaceStability.Evolving +public final class ShutdownHookManager { private static final ShutdownHookManager MGR = new ShutdownHookManager(); private static final Logger LOG = LoggerFactory.getLogger(ShutdownHookManager.class); - private static final long TIMEOUT_DEFAULT = 10; - private static final TimeUnit TIME_UNIT_DEFAULT = TimeUnit.SECONDS; + + /** Minimum shutdown timeout: {@value} second(s). */ + public static final long TIMEOUT_MINIMUM = 1; + + /** The default time unit used: seconds. */ + public static final TimeUnit TIME_UNIT_DEFAULT = TimeUnit.SECONDS; private static final ExecutorService EXECUTOR = HadoopExecutors.newSingleThreadExecutor(new ThreadFactoryBuilder() - .setDaemon(true).build()); + .setDaemon(true) + .setNameFormat("shutdown-hook-%01d") + .build()); + static { try { Runtime.getRuntime().addShutdownHook( new Thread() { @Override public void run() { - MGR.shutdownInProgress.set(true); - for (HookEntry entry: MGR.getShutdownHooksInOrder()) { - Future future = EXECUTOR.submit(entry.getHook()); - try { - future.get(entry.getTimeout(), entry.getTimeUnit()); - } catch (TimeoutException ex) { - future.cancel(true); - LOG.warn("ShutdownHook '" + entry.getHook().getClass(). - getSimpleName() + "' timeout, " + ex.toString(), ex); - } catch (Throwable ex) { - LOG.warn("ShutdownHook '" + entry.getHook().getClass(). - getSimpleName() + "' failed, " + ex.toString(), ex); - } - } - try { - EXECUTOR.shutdown(); - if (!EXECUTOR.awaitTermination(TIMEOUT_DEFAULT, - TIME_UNIT_DEFAULT)) { - LOG.error("ShutdownHookManger shutdown forcefully."); - EXECUTOR.shutdownNow(); - } - LOG.debug("ShutdownHookManger complete shutdown."); - } catch (InterruptedException ex) { - LOG.error("ShutdownHookManger interrupted while waiting for " + - "termination.", ex); - EXECUTOR.shutdownNow(); - Thread.currentThread().interrupt(); + if (MGR.shutdownInProgress.getAndSet(true)) { + LOG.info("Shutdown process invoked a second time: ignoring"); + return; } + long started = System.currentTimeMillis(); + int timeoutCount = executeShutdown(); + long ended = System.currentTimeMillis(); + LOG.debug(String.format( + "Completed shutdown in %.3f seconds; Timeouts: %d", + (ended-started)/1000.0, timeoutCount)); + // each of the hooks have executed; now shut down the + // executor itself. + shutdownExecutor(new Configuration()); } } ); @@ -98,19 +109,93 @@ public class ShutdownHookManager { } } + /** + * Execute the shutdown. + * This is exposed purely for testing: do not invoke it. + * @return the number of shutdown hooks which timed out. + */ + @InterfaceAudience.Private + @VisibleForTesting + static int executeShutdown() { + int timeouts = 0; + for (HookEntry entry: MGR.getShutdownHooksInOrder()) { + Future future = EXECUTOR.submit(entry.getHook()); + try { + future.get(entry.getTimeout(), entry.getTimeUnit()); + } catch (TimeoutException ex) { + timeouts++; + future.cancel(true); + LOG.warn("ShutdownHook '" + entry.getHook().getClass(). + getSimpleName() + "' timeout, " + ex.toString(), ex); + } catch (Throwable ex) { + LOG.warn("ShutdownHook '" + entry.getHook().getClass(). + getSimpleName() + "' failed, " + ex.toString(), ex); + } + } + return timeouts; + } + + /** + * Shutdown the executor thread itself. + * @param conf the configuration containing the shutdown timeout setting. + */ + private static void shutdownExecutor(final Configuration conf) { + try { + EXECUTOR.shutdown(); + long shutdownTimeout = getShutdownTimeout(conf); + if (!EXECUTOR.awaitTermination( + shutdownTimeout, + TIME_UNIT_DEFAULT)) { + // timeout waiting for the + LOG.error("ShutdownHookManger shutdown forcefully after" + + " {} seconds.", shutdownTimeout); + EXECUTOR.shutdownNow(); + } + LOG.debug("ShutdownHookManger completed shutdown."); + } catch (InterruptedException ex) { + // interrupted. + LOG.error("ShutdownHookManger interrupted while waiting for " + + "termination.", ex); + EXECUTOR.shutdownNow(); + Thread.currentThread().interrupt(); + } + } + /** * Return ShutdownHookManager singleton. * * @return ShutdownHookManager singleton. */ + @InterfaceAudience.Public public static ShutdownHookManager get() { return MGR; } + /** + * Get the shutdown timeout in seconds, from the supplied + * configuration. + * @param conf configuration to use. + * @return a timeout, always greater than or equal to {@link #TIMEOUT_MINIMUM} + */ + @InterfaceAudience.Private + @VisibleForTesting + static long getShutdownTimeout(Configuration conf) { + long duration = conf.getTimeDuration( + SERVICE_SHUTDOWN_TIMEOUT, + SERVICE_SHUTDOWN_TIMEOUT_DEFAULT, + TIME_UNIT_DEFAULT); + if (duration < TIMEOUT_MINIMUM) { + duration = TIMEOUT_MINIMUM; + } + return duration; + } + /** * Private structure to store ShutdownHook, its priority and timeout * settings. */ + @InterfaceAudience.Private + @VisibleForTesting static class HookEntry { private final Runnable hook; private final int priority; @@ -118,7 +203,9 @@ public class ShutdownHookManager { private final TimeUnit unit; HookEntry(Runnable hook, int priority) { - this(hook, priority, TIMEOUT_DEFAULT, TIME_UNIT_DEFAULT); + this(hook, priority, + getShutdownTimeout(new Configuration()), + TIME_UNIT_DEFAULT); } HookEntry(Runnable hook, int priority, long timeout, TimeUnit unit) { @@ -176,10 +263,12 @@ public class ShutdownHookManager { * * @return the list of shutdownHooks in order of execution. */ + @InterfaceAudience.Private + @VisibleForTesting List getShutdownHooksInOrder() { List list; synchronized (MGR.hooks) { - list = new ArrayList(MGR.hooks); + list = new ArrayList<>(MGR.hooks); } Collections.sort(list, new Comparator() { @@ -200,6 +289,8 @@ public class ShutdownHookManager { * @param shutdownHook shutdownHook Runnable * @param priority priority of the shutdownHook. */ + @InterfaceAudience.Public + @InterfaceStability.Stable public void addShutdownHook(Runnable shutdownHook, int priority) { if (shutdownHook == null) { throw new IllegalArgumentException("shutdownHook cannot be NULL"); @@ -223,6 +314,8 @@ public class ShutdownHookManager { * @param timeout timeout of the shutdownHook * @param unit unit of the timeout TimeUnit */ + @InterfaceAudience.Public + @InterfaceStability.Stable public void addShutdownHook(Runnable shutdownHook, int priority, long timeout, TimeUnit unit) { if (shutdownHook == null) { @@ -242,6 +335,8 @@ public class ShutdownHookManager { * @return TRUE if the shutdownHook was registered and removed, * FALSE otherwise. */ + @InterfaceAudience.Public + @InterfaceStability.Stable public boolean removeShutdownHook(Runnable shutdownHook) { if (shutdownInProgress.get()) { throw new IllegalStateException("Shutdown in progress, cannot remove a " + @@ -256,6 +351,8 @@ public class ShutdownHookManager { * @param shutdownHook shutdownHook to check if registered. * @return TRUE/FALSE depending if the shutdownHook is is registered. */ + @InterfaceAudience.Public + @InterfaceStability.Stable public boolean hasShutdownHook(Runnable shutdownHook) { return hooks.contains(new HookEntry(shutdownHook, 0)); } @@ -265,6 +362,8 @@ public class ShutdownHookManager { * * @return TRUE if the shutdown is in progress, otherwise FALSE. */ + @InterfaceAudience.Public + @InterfaceStability.Stable public boolean isShutdownInProgress() { return shutdownInProgress.get(); } @@ -272,7 +371,9 @@ public class ShutdownHookManager { /** * clear all registered shutdownHooks. */ + @InterfaceAudience.Public + @InterfaceStability.Stable public void clearShutdownHooks() { hooks.clear(); } -} \ No newline at end of file +} diff --git a/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml b/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml index bc789f7a407..a4472cf0b22 100644 --- a/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml +++ b/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml @@ -540,6 +540,22 @@ + + hadoop.service.shutdown.timeout + 30s + + Timeout to wait for each shutdown operation to complete. + If a hook takes longer than this time to complete, it will be interrupted, + so the service will shutdown. This allows the service shutdown + to recover from a blocked operation. + Some shutdown hooks may need more time than this, for example when + a large amount of data needs to be uploaded to an object store. + In this situation: increase the timeout. + + The minimum duration of the timeout is 1 second, "1s". + + + hadoop.rpc.protection authentication diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestShutdownHookManager.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestShutdownHookManager.java index 2aa5e95b043..03fa903170f 100644 --- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestShutdownHookManager.java +++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestShutdownHookManager.java @@ -17,97 +17,285 @@ */ package org.apache.hadoop.util; -import org.apache.commons.lang.exception.ExceptionUtils; -import org.slf4j.LoggerFactory; -import org.junit.Assert; +import java.util.List; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicInteger; + +import org.junit.After; import org.junit.Test; import org.slf4j.Logger; +import org.slf4j.LoggerFactory; -import java.util.concurrent.TimeUnit; +import org.apache.hadoop.conf.Configuration; import static java.lang.Thread.sleep; +import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.SERVICE_SHUTDOWN_TIMEOUT; +import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.SERVICE_SHUTDOWN_TIMEOUT_DEFAULT; +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; +import static org.junit.Assert.assertNotEquals; +import static org.junit.Assert.assertNotNull; +import static org.junit.Assert.assertTrue; public class TestShutdownHookManager { + static final Logger LOG = LoggerFactory.getLogger(TestShutdownHookManager.class.getName()); + /** + * remove all the shutdown hooks so that they never get invoked later + * on in this test process. + */ + @After + public void clearShutdownHooks() { + ShutdownHookManager.get().clearShutdownHooks(); + } + + /** + * Verify hook registration, then execute the hook callback stage + * of shutdown to verify invocation, execution order and timeout + * processing. + */ @Test public void shutdownHookManager() { ShutdownHookManager mgr = ShutdownHookManager.get(); - Assert.assertNotNull(mgr); - Assert.assertEquals(0, mgr.getShutdownHooksInOrder().size()); - Runnable hook1 = new Runnable() { - @Override - public void run() { - LOG.info("Shutdown hook1 complete."); - } - }; - Runnable hook2 = new Runnable() { - @Override - public void run() { - LOG.info("Shutdown hook2 complete."); - } - }; - - Runnable hook3 = new Runnable() { - @Override - public void run() { - try { - sleep(3000); - LOG.info("Shutdown hook3 complete."); - } catch (InterruptedException ex) { - LOG.info("Shutdown hook3 interrupted exception:", - ExceptionUtils.getStackTrace(ex)); - Assert.fail("Hook 3 should not timeout."); - } - } - }; - - Runnable hook4 = new Runnable() { - @Override - public void run() { - try { - sleep(3500); - LOG.info("Shutdown hook4 complete."); - Assert.fail("Hook 4 should timeout"); - } catch (InterruptedException ex) { - LOG.info("Shutdown hook4 interrupted exception:", - ExceptionUtils.getStackTrace(ex)); - } - } - }; + assertNotNull("No ShutdownHookManager", mgr); + assertEquals(0, mgr.getShutdownHooksInOrder().size()); + Hook hook1 = new Hook("hook1", 0, false); + Hook hook2 = new Hook("hook2", 0, false); + Hook hook3 = new Hook("hook3", 1000, false); + Hook hook4 = new Hook("hook4", 25000, true); + Hook hook5 = new Hook("hook5", + (SERVICE_SHUTDOWN_TIMEOUT_DEFAULT + 1) * 1000, true); mgr.addShutdownHook(hook1, 0); - Assert.assertTrue(mgr.hasShutdownHook(hook1)); - Assert.assertEquals(1, mgr.getShutdownHooksInOrder().size()); - Assert.assertEquals(hook1, mgr.getShutdownHooksInOrder().get(0).getHook()); - mgr.removeShutdownHook(hook1); - Assert.assertFalse(mgr.hasShutdownHook(hook1)); + assertTrue(mgr.hasShutdownHook(hook1)); + assertEquals(1, mgr.getShutdownHooksInOrder().size()); + assertEquals(hook1, mgr.getShutdownHooksInOrder().get(0).getHook()); + assertTrue(mgr.removeShutdownHook(hook1)); + assertFalse(mgr.hasShutdownHook(hook1)); + assertFalse(mgr.removeShutdownHook(hook1)); mgr.addShutdownHook(hook1, 0); - Assert.assertTrue(mgr.hasShutdownHook(hook1)); - Assert.assertEquals(1, mgr.getShutdownHooksInOrder().size()); - Assert.assertTrue(mgr.hasShutdownHook(hook1)); - Assert.assertEquals(1, mgr.getShutdownHooksInOrder().size()); + assertTrue(mgr.hasShutdownHook(hook1)); + assertEquals(1, mgr.getShutdownHooksInOrder().size()); + assertEquals(SERVICE_SHUTDOWN_TIMEOUT_DEFAULT, + mgr.getShutdownHooksInOrder().get(0).getTimeout()); mgr.addShutdownHook(hook2, 1); - Assert.assertTrue(mgr.hasShutdownHook(hook1)); - Assert.assertTrue(mgr.hasShutdownHook(hook2)); - Assert.assertEquals(2, mgr.getShutdownHooksInOrder().size()); - Assert.assertEquals(hook2, mgr.getShutdownHooksInOrder().get(0).getHook()); - Assert.assertEquals(hook1, mgr.getShutdownHooksInOrder().get(1).getHook()); + assertTrue(mgr.hasShutdownHook(hook1)); + assertTrue(mgr.hasShutdownHook(hook2)); + assertEquals(2, mgr.getShutdownHooksInOrder().size()); + assertEquals(hook2, mgr.getShutdownHooksInOrder().get(0).getHook()); + assertEquals(hook1, mgr.getShutdownHooksInOrder().get(1).getHook()); // Test hook finish without timeout mgr.addShutdownHook(hook3, 2, 4, TimeUnit.SECONDS); - Assert.assertTrue(mgr.hasShutdownHook(hook3)); - Assert.assertEquals(hook3, mgr.getShutdownHooksInOrder().get(0).getHook()); - Assert.assertEquals(4, mgr.getShutdownHooksInOrder().get(0).getTimeout()); + assertTrue(mgr.hasShutdownHook(hook3)); + assertEquals(hook3, mgr.getShutdownHooksInOrder().get(0).getHook()); + assertEquals(4, mgr.getShutdownHooksInOrder().get(0).getTimeout()); - // Test hook finish with timeout - mgr.addShutdownHook(hook4, 3, 2, TimeUnit.SECONDS); - Assert.assertTrue(mgr.hasShutdownHook(hook4)); - Assert.assertEquals(hook4, mgr.getShutdownHooksInOrder().get(0).getHook()); - Assert.assertEquals(2, mgr.getShutdownHooksInOrder().get(0).getTimeout()); - LOG.info("Shutdown starts here"); + // Test hook finish with timeout; highest priority + int hook4timeout = 2; + mgr.addShutdownHook(hook4, 3, hook4timeout, TimeUnit.SECONDS); + assertTrue(mgr.hasShutdownHook(hook4)); + assertEquals(hook4, mgr.getShutdownHooksInOrder().get(0).getHook()); + assertEquals(2, mgr.getShutdownHooksInOrder().get(0).getTimeout()); + + // a default timeout hook and verify it gets the default timeout + mgr.addShutdownHook(hook5, 5); + ShutdownHookManager.HookEntry hookEntry5 = mgr.getShutdownHooksInOrder() + .get(0); + assertEquals(hook5, hookEntry5.getHook()); + assertEquals("default timeout not used", + ShutdownHookManager.getShutdownTimeout(new Configuration()), + hookEntry5.getTimeout()); + assertEquals("hook priority", 5, hookEntry5.getPriority()); + // remove this to avoid a longer sleep in the test run + assertTrue("failed to remove " + hook5, + mgr.removeShutdownHook(hook5)); + + + // now execute the hook shutdown sequence + INVOCATION_COUNT.set(0); + LOG.info("invoking executeShutdown()"); + int timeouts = ShutdownHookManager.executeShutdown(); + LOG.info("Shutdown completed"); + assertEquals("Number of timed out hooks", 1, timeouts); + + List hooks + = mgr.getShutdownHooksInOrder(); + + // analyze the hooks + for (ShutdownHookManager.HookEntry entry : hooks) { + Hook hook = (Hook) entry.getHook(); + assertTrue("Was not invoked " + hook, hook.invoked); + // did any hook raise an exception? + hook.maybeThrowAssertion(); + } + + // check the state of some of the invoked hooks + // hook4 was invoked first, but it timed out. + assertEquals("Expected to be invoked first " + hook4, + 1, hook4.invokedOrder); + assertFalse("Expected to time out " + hook4, hook4.completed); + + + // hook1 completed, but in order after the others, so its start time + // is the longest. + assertTrue("Expected to complete " + hook1, hook1.completed); + long invocationInterval = hook1.startTime - hook4.startTime; + assertTrue("invocation difference too short " + invocationInterval, + invocationInterval >= hook4timeout * 1000); + assertTrue("sleeping hook4 blocked other threads for " + invocationInterval, + invocationInterval < hook4.sleepTime); + + // finally, clear the hooks + mgr.clearShutdownHooks(); + // and verify that the hooks are empty + assertFalse(mgr.hasShutdownHook(hook1)); + assertEquals("shutdown hook list is not empty", + 0, + mgr.getShutdownHooksInOrder().size()); + } + + @Test + public void testShutdownTimeoutConfiguration() throws Throwable { + // set the shutdown timeout and verify it can be read back. + Configuration conf = new Configuration(); + long shutdownTimeout = 5; + conf.setTimeDuration(SERVICE_SHUTDOWN_TIMEOUT, + shutdownTimeout, TimeUnit.SECONDS); + assertEquals(SERVICE_SHUTDOWN_TIMEOUT, + shutdownTimeout, + ShutdownHookManager.getShutdownTimeout(conf)); + } + + /** + * Verify that low timeouts simply fall back to + * {@link ShutdownHookManager#TIMEOUT_MINIMUM}. + */ + @Test + public void testShutdownTimeoutBadConfiguration() throws Throwable { + // set the shutdown timeout and verify it can be read back. + Configuration conf = new Configuration(); + long shutdownTimeout = 50; + conf.setTimeDuration(SERVICE_SHUTDOWN_TIMEOUT, + shutdownTimeout, TimeUnit.NANOSECONDS); + assertEquals(SERVICE_SHUTDOWN_TIMEOUT, + ShutdownHookManager.TIMEOUT_MINIMUM, + ShutdownHookManager.getShutdownTimeout(conf)); + } + + /** + * Verifies that a hook cannot be re-registered: an attempt to do so + * will simply be ignored. + */ + @Test + public void testDuplicateRegistration() throws Throwable { + ShutdownHookManager mgr = ShutdownHookManager.get(); + Hook hook = new Hook("hook1", 0, false); + + // add the hook + mgr.addShutdownHook(hook, 2, 1, TimeUnit.SECONDS); + + // add it at a higher priority. This will be ignored. + mgr.addShutdownHook(hook, 5); + List hookList + = mgr.getShutdownHooksInOrder(); + assertEquals("Hook added twice", 1, hookList.size()); + ShutdownHookManager.HookEntry entry = hookList.get(0); + assertEquals("priority of hook", 2, entry.getPriority()); + assertEquals("timeout of hook", 1, entry.getTimeout()); + + // remove the hook + assertTrue("failed to remove hook " + hook, mgr.removeShutdownHook(hook)); + // which will fail a second time + assertFalse("expected hook removal to fail", mgr.removeShutdownHook(hook)); + + // now register it + mgr.addShutdownHook(hook, 5); + hookList = mgr.getShutdownHooksInOrder(); + entry = hookList.get(0); + assertEquals("priority of hook", 5, entry.getPriority()); + assertNotEquals("timeout of hook", 1, entry.getTimeout()); + + } + + private static final AtomicInteger INVOCATION_COUNT = new AtomicInteger(); + + /** + * Hooks for testing; save state for ease of asserting on + * invocation. + */ + private class Hook implements Runnable { + + private final String name; + private final long sleepTime; + private final boolean expectFailure; + private AssertionError assertion; + private boolean invoked; + private int invokedOrder; + private boolean completed; + private boolean interrupted; + private long startTime; + + Hook(final String name, + final long sleepTime, + final boolean expectFailure) { + this.name = name; + this.sleepTime = sleepTime; + this.expectFailure = expectFailure; + } + + @Override + public void run() { + try { + invoked = true; + invokedOrder = INVOCATION_COUNT.incrementAndGet(); + startTime = System.currentTimeMillis(); + LOG.info("Starting shutdown of {} with sleep time of {}", + name, sleepTime); + if (sleepTime > 0) { + sleep(sleepTime); + } + LOG.info("Completed shutdown of {}", name); + completed = true; + if (expectFailure) { + assertion = new AssertionError("Expected a failure of " + name); + } + } catch (InterruptedException ex) { + LOG.info("Shutdown {} interrupted exception", name, ex); + interrupted = true; + if (!expectFailure) { + assertion = new AssertionError("Timeout of " + name, ex); + } + } + maybeThrowAssertion(); + } + + /** + * Raise any exception generated during the shutdown process. + * @throws AssertionError any assertion from the shutdown. + */ + void maybeThrowAssertion() throws AssertionError { + if (assertion != null) { + throw assertion; + } + } + + @Override + public String toString() { + final StringBuilder sb = new StringBuilder("Hook{"); + sb.append("name='").append(name).append('\''); + sb.append(", sleepTime=").append(sleepTime); + sb.append(", expectFailure=").append(expectFailure); + sb.append(", invoked=").append(invoked); + sb.append(", invokedOrder=").append(invokedOrder); + sb.append(", completed=").append(completed); + sb.append(", interrupted=").append(interrupted); + sb.append('}'); + return sb.toString(); + } } }