【踩坑日记】我的@Scheduled 怎么不运行了？
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背景
近期开发着定制项目，因为并发要求较低但业务繁杂，需要多个定时任务执行数据和业务。
然后呢就在那么一个光和日丽，微风徐徐的下午
它就那样不运行了
原因
怎么就不运行了呢?怎么就不运行了呢?怎么就不运行了呢?
我也不知道呀？
来回忆一下怎么创建一个定时任务
- 启动Spring的定时任务能力
@EnableScheduling - 在被Spring管理的类中，在要定时执行的方法上加上
@Scheduled(xxx)
第一步是加上@EnableScheduling,这个注解干了什么呢
@EnableScheduling
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(SchedulingConfiguration.class)
@Documented
public @interface EnableScheduling {
}
@EnableScheduling注解Import了SchedulingConfiguration类
@Configuration
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public class SchedulingConfiguration {
@Bean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public ScheduledAnnotationBeanPostProcessor scheduledAnnotationProcessor() {
return new ScheduledAnnotationBeanPostProcessor();
}
}
SchedulingConfiguration类创建了个一个ScheduledAnnotationBeanPostProcessor类型，名为org.springframework.context.annotation.internalScheduledAnnotationProcessor的Bean
@Configuration
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public class SchedulingConfiguration {
@Bean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public ScheduledAnnotationBeanPostProcessor scheduledAnnotationProcessor() {
return new ScheduledAnnotationBeanPostProcessor();
}
}
public abstract class TaskManagementConfigUtils {
/**
* The bean name of the internally managed Scheduled annotation processor.
*/
public static final String SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME =
"org.springframework.context.annotation.internalScheduledAnnotationProcessor";
……
来看看ScheduledAnnotationBeanPostProcessor的源码
public class ScheduledAnnotationBeanPostProcessor
implements ScheduledTaskHolder, MergedBeanDefinitionPostProcessor, DestructionAwareBeanPostProcessor,
Ordered, EmbeddedValueResolverAware, BeanNameAware, BeanFactoryAware, ApplicationContextAware,
SmartInitializingSingleton, ApplicationListener<ContextRefreshedEvent>, DisposableBean {
……
ScheduledAnnotationBeanPostProcessor实现了spring相关生命周期的处理器、容器以及事件处理器，他的注解上说明了这个处理器用于注册注解了@Scheduled的方法，来看看他的#postProcessAfterInitialization方法
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) {
if (bean instanceof AopInfrastructureBean || bean instanceof TaskScheduler ||
bean instanceof ScheduledExecutorService) {
// Ignore AOP infrastructure such as scoped proxies.
return bean;
}
Class<?> targetClass = AopProxyUtils.ultimateTargetClass(bean);
if (!this.nonAnnotatedClasses.contains(targetClass)) {
Map<Method, Set<Scheduled>> annotatedMethods = MethodIntrospector.selectMethods(targetClass,
(MethodIntrospector.MetadataLookup<Set<Scheduled>>) method -> {
Set<Scheduled> scheduledMethods = AnnotatedElementUtils.getMergedRepeatableAnnotations(
method, Scheduled.class, Schedules.class);
return (!scheduledMethods.isEmpty() ? scheduledMethods : null);
});
if (annotatedMethods.isEmpty()) {
this.nonAnnotatedClasses.add(targetClass);
if (logger.isTraceEnabled()) {
logger.trace("No @Scheduled annotations found on bean class: " + targetClass);
}
}
else {
// Non-empty set of methods
annotatedMethods.forEach((method, scheduledMethods) ->
scheduledMethods.forEach(scheduled -> processScheduled(scheduled, method, bean)));
if (logger.isTraceEnabled()) {
logger.trace(annotatedMethods.size() + " @Scheduled methods processed on bean '" + beanName +
"': " + annotatedMethods);
}
}
}
return bean;
}
这个方法找到所有注解了@Scheduled的方法，然后遍历调用processScheduled，来看看他的处理方法#processScheduled
/**
* Process the given {@code @Scheduled} method declaration on the given bean.
* @param scheduled the @Scheduled annotation
* @param method the method that the annotation has been declared on
* @param bean the target bean instance
* @see #createRunnable(Object, Method)
*/
protected void processScheduled(Scheduled scheduled, Method method, Object bean) {
try {
Runnable runnable = createRunnable(bean, method);
boolean processedSchedule = false;
String errorMessage =
"Exactly one of the 'cron', 'fixedDelay(String)', or 'fixedRate(String)' attributes is required";
Set<ScheduledTask> tasks = new LinkedHashSet<>(4);
// Determine initial delay
long initialDelay = scheduled.initialDelay();
String initialDelayString = scheduled.initialDelayString();
if (StringUtils.hasText(initialDelayString)) {
Assert.isTrue(initialDelay < 0, "Specify 'initialDelay' or 'initialDelayString', not both");
if (this.embeddedValueResolver != null) {
initialDelayString = this.embeddedValueResolver.resolveStringValue(initialDelayString);
}
if (StringUtils.hasLength(initialDelayString)) {
try {
initialDelay = parseDelayAsLong(initialDelayString);
}
catch (RuntimeException ex) {
throw new IllegalArgumentException(
"Invalid initialDelayString value "" + initialDelayString + "" - cannot parse into long");
}
}
}
// Check cron expression
String cron = scheduled.cron();
if (StringUtils.hasText(cron)) {
String zone = scheduled.zone();
if (this.embeddedValueResolver != null) {
cron = this.embeddedValueResolver.resolveStringValue(cron);
zone = this.embeddedValueResolver.resolveStringValue(zone);
}
if (StringUtils.hasLength(cron)) {
Assert.isTrue(initialDelay == -1, "'initialDelay' not supported for cron triggers");
processedSchedule = true;
if (!Scheduled.CRON_DISABLED.equals(cron)) {
TimeZone timeZone;
if (StringUtils.hasText(zone)) {
timeZone = StringUtils.parseTimeZoneString(zone);
}
else {
timeZone = TimeZone.getDefault();
}
tasks.add(this.registrar.scheduleCronTask(new CronTask(runnable, new CronTrigger(cron, timeZone))));
}
}
}
// At this point we don't need to differentiate between initial delay set or not anymore
if (initialDelay < 0) {
initialDelay = 0;
}
// Check fixed delay
long fixedDelay = scheduled.fixedDelay();
if (fixedDelay >= 0) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
}
String fixedDelayString = scheduled.fixedDelayString();
if (StringUtils.hasText(fixedDelayString)) {
if (this.embeddedValueResolver != null) {
fixedDelayString = this.embeddedValueResolver.resolveStringValue(fixedDelayString);
}
if (StringUtils.hasLength(fixedDelayString)) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
try {
fixedDelay = parseDelayAsLong(fixedDelayString);
}
catch (RuntimeException ex) {
throw new IllegalArgumentException(
"Invalid fixedDelayString value "" + fixedDelayString + "" - cannot parse into long");
}
tasks.add(this.registrar.scheduleFixedDelayTask(new FixedDelayTask(runnable, fixedDelay, initialDelay)));
}
}
// Check fixed rate
long fixedRate = scheduled.fixedRate();
if (fixedRate >= 0) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
}
String fixedRateString = scheduled.fixedRateString();
if (StringUtils.hasText(fixedRateString)) {
if (this.embeddedValueResolver != null) {
fixedRateString = this.embeddedValueResolver.resolveStringValue(fixedRateString);
}
if (StringUtils.hasLength(fixedRateString)) {
Assert.isTrue(!processedSchedule, errorMessage);
processedSchedule = true;
try {
fixedRate = parseDelayAsLong(fixedRateString);
}
catch (RuntimeException ex) {
throw new IllegalArgumentException(
"Invalid fixedRateString value "" + fixedRateString + "" - cannot parse into long");
}
tasks.add(this.registrar.scheduleFixedRateTask(new FixedRateTask(runnable, fixedRate, initialDelay)));
}
}
// Check whether we had any attribute set
Assert.isTrue(processedSchedule, errorMessage);
// Finally register the scheduled tasks
synchronized (this.scheduledTasks) {
Set<ScheduledTask> regTasks = this.scheduledTasks.computeIfAbsent(bean, key -> new LinkedHashSet<>(4));
regTasks.addAll(tasks);
}
}
catch (IllegalArgumentException ex) {
throw new IllegalStateException(
"Encountered invalid @Scheduled method '" + method.getName() + "': " + ex.getMessage());
}
}
在了解处理过程之前，先来看看Scheduled有什么参数
public @interface Scheduled {
/**
* A special cron expression value that indicates a disabled trigger: {@value}.
* <p>This is primarily meant for use with ${...} placeholders, allowing for
* external disabling of corresponding scheduled methods.
* @since 5.1
*/
String CRON_DISABLED = "-";
/**
* A cron-like expression, extending the usual UN*X definition to include triggers
* on the second as well as minute, hour, day of month, month and day of week.
* <p>E.g. {@code "0 * * * * MON-FRI"} means once per minute on weekdays
* (at the top of the minute - the 0th second).
* <p>The special value {@link #CRON_DISABLED "-"} indicates a disabled cron trigger,
* primarily meant for externally specified values resolved by a ${...} placeholder.
* @return an expression that can be parsed to a cron schedule
* @see org.springframework.scheduling.support.CronSequenceGenerator
*/
String cron() default "";
/**
* A time zone for which the cron expression will be resolved. By default, this
* attribute is the empty String (i.e. the server's local time zone will be used).
* @return a zone id accepted by {@link java.util.TimeZone#getTimeZone(String)},
* or an empty String to indicate the server's default time zone
* @since 4.0
* @see org.springframework.scheduling.support.CronTrigger#CronTrigger(String, java.util.TimeZone)
* @see java.util.TimeZone
*/
String zone() default "";
/**
* Execute the annotated method with a fixed period in milliseconds between the
* end of the last invocation and the start of the next.
* @return the delay in milliseconds
*/
long fixedDelay() default -1;
/**
* Execute the annotated method with a fixed period in milliseconds between the
* end of the last invocation and the start of the next.
* @return the delay in milliseconds as a String value, e.g. a placeholder
* or a {@link java.time.Duration#parse java.time.Duration} compliant value
* @since 3.2.2
*/
String fixedDelayString() default "";
/**
* Execute the annotated method with a fixed period in milliseconds between
* invocations.
* @return the period in milliseconds
*/
long fixedRate() default -1;
/**
* Execute the annotated method with a fixed period in milliseconds between
* invocations.
* @return the period in milliseconds as a String value, e.g. a placeholder
* or a {@link java.time.Duration#parse java.time.Duration} compliant value
* @since 3.2.2
*/
String fixedRateString() default "";
/**
* Number of milliseconds to delay before the first execution of a
* {@link #fixedRate()} or {@link #fixedDelay()} task.
* @return the initial delay in milliseconds
* @since 3.2
*/
long initialDelay() default -1;
/**
* Number of milliseconds to delay before the first execution of a
* {@link #fixedRate()} or {@link #fixedDelay()} task.
* @return the initial delay in milliseconds as a String value, e.g. a placeholder
* or a {@link java.time.Duration#parse java.time.Duration} compliant value
* @since 3.2.2
*/
String initialDelayString() default "";
}
@Scheduled提供了
- cron
- zone
- fixedDelay、fixedDelayString
- fixedRate、fixedRateString
- initialDelay、initialDelayString
processScheduled的执行过程如下：
- 根据@Scheduled注解的参数构建任务
- 根据对应的任务类型注册成ScheduledTask
- 将任务加入到scheduledTasks任务列表
细心且多智的我们肯定还记得ScheduledAnnotationBeanPostProcessor还实现了ApplicationListener和SmartInitializingSingleton
@Override
public void afterSingletonsInstantiated() {
// Remove resolved singleton classes from cache
this.nonAnnotatedClasses.clear();
if (this.applicationContext == null) {
// Not running in an ApplicationContext -> register tasks early...
finishRegistration();
}
}
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
if (event.getApplicationContext() == this.applicationContext) {
// Running in an ApplicationContext -> register tasks this late...
// giving other ContextRefreshedEvent listeners a chance to perform
// their work at the same time (e.g. Spring Batch's job registration).
finishRegistration();
}
}
二者都调用了私有方法#finishRegistration,这个方法是完成注册，将任务队列注册到Spring容器中交由Spring管理
到这里 定时任务知道怎么来的了，但是这和他不运行没啥关系啊？
在Spring依赖包中，我们可以看到这个interface TaskScheduler
/**
* Task scheduler interface that abstracts the scheduling of
* {@link Runnable Runnables} based on different kinds of triggers.
*
* <p>This interface is separate from {@link SchedulingTaskExecutor} since it
* usually represents for a different kind of backend, i.e. a thread pool with
* different characteristics and capabilities. Implementations may implement
* both interfaces if they can handle both kinds of execution characteristics.
*
* <p>The 'default' implementation is
* {@link org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler},
* wrapping a native {@link java.util.concurrent.ScheduledExecutorService}
* and adding extended trigger capabilities.
*
* <p>This interface is roughly equivalent to a JSR-236
* {@code ManagedScheduledExecutorService} as supported in Java EE 7
* environments but aligned with Spring's {@code TaskExecutor} model.
*
* @author Juergen Hoeller
* @since 3.0
* @see org.springframework.core.task.TaskExecutor
* @see java.util.concurrent.ScheduledExecutorService
* @see org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler
*/
public interface TaskScheduler {
/**
* Schedule the given {@link Runnable}, invoking it whenever the trigger
* indicates a next execution time.
* <p>Execution will end once the scheduler shuts down or the returned
* {@link ScheduledFuture} gets cancelled.
* @param task the Runnable to execute whenever the trigger fires
* @param trigger an implementation of the {@link Trigger} interface,
* e.g. a {@link org.springframework.scheduling.support.CronTrigger} object
* wrapping a cron expression
* @return a {@link ScheduledFuture} representing pending completion of the task,
* or {@code null} if the given Trigger object never fires (i.e. returns
* {@code null} from {@link Trigger#nextExecutionTime})
* @throws org.springframework.core.task.TaskRejectedException if the given task was not accepted
* for internal reasons (e.g. a pool overload handling policy or a pool shutdown in progress)
* @see org.springframework.scheduling.support.CronTrigger
*/
@Nullable
ScheduledFuture<?> schedule(Runnable task, Trigger trigger);
……
根据注解所描述的内容说明我们可以知道，这就是定时任务执行的接口，来看看schedule方法的实现
先来看看ConcurrentTaskScheduler的实现
@Override
@Nullable
public ScheduledFuture<?> schedule(Runnable task, Trigger trigger) {
try {
if (this.enterpriseConcurrentScheduler) {
return new EnterpriseConcurrentTriggerScheduler().schedule(decorateTask(task, true), trigger);
}
else {
ErrorHandler errorHandler =
(this.errorHandler != null ? this.errorHandler : TaskUtils.getDefaultErrorHandler(true));
return new ReschedulingRunnable(task, trigger, this.scheduledExecutor, errorHandler).schedule();
}
}
catch (RejectedExecutionException ex) {
throw new TaskRejectedException("Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex);
}
}
查看ConcurrentTaskScheduler的源码，我们可以看到他的默认构造方法和初始化方法如下
public ConcurrentTaskScheduler() {
super();
this.scheduledExecutor = initScheduledExecutor(null);
}
private ScheduledExecutorService initScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) {
if (scheduledExecutor != null) {
this.scheduledExecutor = scheduledExecutor;
this.enterpriseConcurrentScheduler = (managedScheduledExecutorServiceClass != null &&
managedScheduledExecutorServiceClass.isInstance(scheduledExecutor));
}
else {
this.scheduledExecutor = Executors.newSingleThreadScheduledExecutor();
this.enterpriseConcurrentScheduler = false;
}
return this.scheduledExecutor;
}
可以看到他默认是个单线程的任务提交池，再来看看ThreadPoolTaskScheduler实现的schedule方法
// TaskScheduler implementation
@Override
@Nullable
public ScheduledFuture<?> schedule(Runnable task, Trigger trigger) {
ScheduledExecutorService executor = getScheduledExecutor();
try {
ErrorHandler errorHandler = this.errorHandler;
if (errorHandler == null) {
errorHandler = TaskUtils.getDefaultErrorHandler(true);
}
return new ReschedulingRunnable(task, trigger, executor, errorHandler).schedule();
}
catch (RejectedExecutionException ex) {
throw new TaskRejectedException("Executor [" + executor + "] did not accept task: " + task, ex);
}
}
从源码可以知道，获取ScheduledExecutorService线程池而后提交执行，来看看他的初始化方法
public void initialize() {
if (logger.isInfoEnabled()) {
logger.info("Initializing ExecutorService" + (this.beanName != null ? " '" + this.beanName + "'" : ""));
}
if (!this.threadNamePrefixSet && this.beanName != null) {
setThreadNamePrefix(this.beanName + "-");
}
this.executor = initializeExecutor(this.threadFactory, this.rejectedExecutionHandler);
}
@Override
protected ExecutorService initializeExecutor(
ThreadFactory threadFactory, RejectedExecutionHandler rejectedExecutionHandler) {
this.scheduledExecutor = createExecutor(this.poolSize, threadFactory, rejectedExecutionHandler);
if (this.removeOnCancelPolicy) {
if (this.scheduledExecutor instanceof ScheduledThreadPoolExecutor) {
((ScheduledThreadPoolExecutor) this.scheduledExecutor).setRemoveOnCancelPolicy(true);
}
else {
logger.debug("Could not apply remove-on-cancel policy - not a ScheduledThreadPoolExecutor");
}
}
return this.scheduledExecutor;
}
这里的poolSize在spring的自动配置bean的时候进行设置，代码里的默认值是1
@ConditionalOnClass(ThreadPoolTaskScheduler.class)
@Configuration
@EnableConfigurationProperties(TaskSchedulingProperties.class)
@AutoConfigureAfter(TaskExecutionAutoConfiguration.class)
public class TaskSchedulingAutoConfiguration {
@Bean
@ConditionalOnBean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
@ConditionalOnMissingBean({ SchedulingConfigurer.class, TaskScheduler.class, ScheduledExecutorService.class })
public ThreadPoolTaskScheduler taskScheduler(TaskSchedulerBuilder builder) {
return builder.build();
}
@Bean
@ConditionalOnMissingBean
public TaskSchedulerBuilder taskSchedulerBuilder(TaskSchedulingProperties properties,
ObjectProvider<TaskSchedulerCustomizer> taskSchedulerCustomizers) {
TaskSchedulerBuilder builder = new TaskSchedulerBuilder();
builder = builder.poolSize(properties.getPool().getSize());
builder = builder.threadNamePrefix(properties.getThreadNamePrefix());
builder = builder.customizers(taskSchedulerCustomizers);
return builder;
}
}
@ConfigurationProperties("spring.task.scheduling")
public class TaskSchedulingProperties {
private final Pool pool = new Pool();
public static class Pool {
/**
* Maximum allowed number of threads.
*/
private int size = 1;
public int getSize() {
return this.size;
}
public void setSize(int size) {
this.size = size;
}
}
这时候仿佛我们看到了希望，是否执行线程不足以执行定时任务？
我们先来确定默认的是哪个任务调度器，在org.springframework.boot.autoconfigure.task包下有个TaskSchedulingAutoConfiguration对象
@ConditionalOnClass(ThreadPoolTaskScheduler.class)
@Configuration
@EnableConfigurationProperties(TaskSchedulingProperties.class)
@AutoConfigureAfter(TaskExecutionAutoConfiguration.class)
public class TaskSchedulingAutoConfiguration {
@Bean
@ConditionalOnBean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
@ConditionalOnMissingBean({ SchedulingConfigurer.class, TaskScheduler.class, ScheduledExecutorService.class })
public ThreadPoolTaskScheduler taskScheduler(TaskSchedulerBuilder builder) {
return builder.build();
}
@Bean
@ConditionalOnMissingBean
public TaskSchedulerBuilder taskSchedulerBuilder(TaskSchedulingProperties properties,
ObjectProvider<TaskSchedulerCustomizer> taskSchedulerCustomizers) {
TaskSchedulerBuilder builder = new TaskSchedulerBuilder();
builder = builder.poolSize(properties.getPool().getSize());
builder = builder.threadNamePrefix(properties.getThreadNamePrefix());
builder = builder.customizers(taskSchedulerCustomizers);
return builder;
}
}
按照这个发现，我们给spring.task.scheduling.pool.size配上一个适合的值，应该就成了吧
可是呢
可是呢
可是呢
宿主机的线程怎么炸了啊！！！
查看执行任务发现有存在长期hold线程的任务，任务执行线程没上限？
在org.springframework.boot.autoconfigure.task包下还有个TaskExecutionAutoConfiguration对象
从Execution这个词我们就知道了他是配置任务执行线程池的配置
来看看他的配置参数是什么
@ConfigurationProperties("spring.task.execution")
public class TaskExecutionProperties {
private final Pool pool = new Pool();
……
public static class Pool {
/**
* Queue capacity. An unbounded capacity does not increase the pool and therefore
* ignores the "max-size" property.
*/
private int queueCapacity = Integer.MAX_VALUE;
/**
* Core number of threads.
*/
private int coreSize = 8;
/**
* Maximum allowed number of threads. If tasks are filling up the queue, the pool
* can expand up to that size to accommodate the load. Ignored if the queue is
* unbounded.
*/
private int maxSize = Integer.MAX_VALUE;
/**
* Whether core threads are allowed to time out. This enables dynamic growing and
* shrinking of the pool.
*/
private boolean allowCoreThreadTimeout = true;
/**
* Time limit for which threads may remain idle before being terminated.
*/
private Duration keepAlive = Duration.ofSeconds(60);
……
他是个核心线程只有8最大线程数是int最大值的线程池
察看java应用的stack可以发现，确实很多都是task-开头的线程任务，马上修改
spring.task.execution.pool.maxSize和spring.task.execution.pool.queueCapacity的值
把hold住线程的任务中的代码缺陷修复
果然这就解决了，恢复正常了