Java Spring：选择MICROSECONDS为时间单位时@Scheduled注解报错

Question

根据 Spring 文档https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/scheduling/annotation/Scheduled.html，我们可以使用各种时间单位来调整我们的周期任务（默认为毫秒）。

我想要一个粒度为 1 微秒的任务。因此我定义了：

    @Scheduled(timeUnit = TimeUnit.MICROSECONDS, fixedDelay = 1, initialDelay = 1000)
    public void scheduleTask() throws IdaDatabaseException {...}

但是在启动应用程序或集成测试时，我遇到了一个错误（见下文）。 微秒粒度有什么问题？

java.lang.IllegalStateException: Failed to load ApplicationContext for [MergedContextConfiguration@27d45d8 testClass = com.ida.sr.IdaIsrDbReceiverTest, locations = [], classes = [com.ida.sr.IdaIsrDbReceiver, com.ida.database.config.IdaDatabaseServiceConfiguration, com.ida.tz.appconfig.TzKafkaConfiguration, com.ida.tz.appconfig.TzKafkaConsumerConfiguration, com.ida.appconfig.IdaMonitoringConfig, com.ida.sr.KafkaTestConfig], contextInitializerClasses = [], activeProfiles = [], propertySourceLocations = ["classpath:application-test.properties"], propertySourceProperties = ["org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true"], contextCustomizers = [org.springframework.kafka.test.context.EmbeddedKafkaContextCustomizer@cc7406bd, org.springframework.boot.test.autoconfigure.actuate.observability.ObservabilityContextCustomizerFactory$DisableObservabilityContextCustomizer@9da1, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@7c9bdee9, org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@221dad51, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@73a19967, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.web.client.TestRestTemplateContextCustomizer@756b58a7, org.springframework.boot.test.context.SpringBootTestAnnotation@4514ad9b], contextLoader = org.springframework.boot.test.context.SpringBootContextLoader, parent = null]
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:142)
    at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:127)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:141)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:97)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:241)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
    at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:110)
    at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
    at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:38)
    at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:62)
    at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
    at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
    at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
    at jdk.proxy2/jdk.proxy2.$Proxy5.processTestClass(Unknown Source)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
    at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
    at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:133)
    at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:71)
    at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
    at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
Caused by: java.lang.IllegalArgumentException
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor.scheduleWithFixedDelay(ScheduledThreadPoolExecutor.java:671)
    at org.springframework.scheduling.concurrent.ConcurrentTaskScheduler.scheduleWithFixedDelay(ConcurrentTaskScheduler.java:247)
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleFixedDelayTask(ScheduledTaskRegistrar.java:525)
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleTasks(ScheduledTaskRegistrar.java:406)
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.afterPropertiesSet(ScheduledTaskRegistrar.java:371)
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:319)
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:238)
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:109)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:413)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:370)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:587)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:432)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
    at org.springframework.boot.test.context.SpringBootContextLoader.lambda$loadContext$3(SpringBootContextLoader.java:137)
    at org.springframework.util.function.ThrowingSupplier.get(ThrowingSupplier.java:59)
    at org.springframework.util.function.ThrowingSupplier.get(ThrowingSupplier.java:47)
    at org.springframework.boot.SpringApplication.withHook(SpringApplication.java:1386)
    at org.springframework.boot.test.context.SpringBootContextLoader$ContextLoaderHook.run(SpringBootContextLoader.java:543)
    at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:137)
    at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:108)
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:184)
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:118)
    ... 44 more

Answer 1

我相信您已经发现了调度程序工作方式中的错误。它声称接受TimeUnit，但如果你查看ScheduledAnnotationBeanPostProcessor，你会看到这些行：

long fixedDelay = convertToMillis(scheduled.fixedDelay(), scheduled.timeUnit());
if (fixedDelay >= 0) {
    Assert.isTrue(!processedSchedule, errorMessage);
    ...
}

第一部分将您的微秒转换为毫秒。该逻辑只是做一个除法，duration / milliRatio。根据 fixedDelay 属性，您的持续时间设置为 1，毫秒与微秒的比率为 1000，因此返回 1/1000，四舍五入为 0。这将使您进入 if 块，因为此过程有尚未安排，断言失败并抛出捕获的异常。

换句话说，如果您以微秒或纳秒作为时间单位传递，它似乎不会起作用。

您可能认为您可以将其设置为等于正值的值，但是当它检查固定利率时，您会在几行之后发现另一个陷阱。