我在一個 Bean 中有一些函數(shù)，我想每 5 秒運(yùn)行一次，變量應(yīng)該是“通用的”而不是硬編碼：工作代碼如下：（我已經(jīng)寫在相關(guān)的 XML 中）@Component@EnableSchedulingpublic class CacheManager{ @Scheduled(initialDelay=0,fixedDelay=5000) public void updateConfigurations() { Some Code Here } @Scheduled(initialDelay=0,fixedDelay=5000) public void updateMapping() { Some Code Here }}這兩個函數(shù)每 5 秒執(zhí)行一次。現(xiàn)在當(dāng)我想把它移到 XML 中時：<task:scheduler id="ttScheduler" pool-size="1" /> <task:scheduled-tasks scheduler="ttScheduler"> <task:scheduled ref="cacheManager" method="updateConfigurations" fixed-delay="5000" initial-delay="0" /> <task:scheduled ref="cacheManager" method="updateMapping" fixed-delay="5000" initial-delay="0" /> </task:scheduled-tasks>@Componentpublic class CacheManager{ public void updateConfigurations() { log.info("update configurations"); Some Code log.info("end update configurations"); } public void updateMapping() { Some Code Here }}這兩個函數(shù)都可以毫無延遲地執(zhí)行。輸出：20190127-17:24:48.254 INFO [ttScheduler-1] CacheManager[109] - end update configurations20190127-17:24:48.255 INFO [ttScheduler-1] CacheManager[105] - update configurations20190127-17:24:48.282 INFO [ttScheduler-1] CacheManager[109] - end update configurations20190127-17:24:48.283 INFO [ttScheduler-1] CacheManager[105] - update configurations20190127-17:24:48.311 INFO [ttScheduler-1] CacheManager[109] - end update configurations20190127-17:24:48.312 INFO [ttScheduler-1] CacheManager[105] - update configurations20190127-17:24:48.337 INFO [ttScheduler-1] CacheManager[109] - end update configurations20190127-17:24:48.337 INFO [ttScheduler-1] CacheManager[105] - update configurations20190127-17:24:48.362 INFO [ttScheduler-1] CacheManager[109] - end update configuration......
1 回答
LEATH
TA貢獻(xiàn)1936條經(jīng)驗 獲得超7個贊
這可能是因為在 XML 中您使用固定速率，而在 Java 配置中您使用固定延遲。正如官方 Spring Doc所述：
...固定延遲指示每個任務(wù)執(zhí)行完成后等待的毫秒數(shù)。另一個選項是fixed-rate，表示該方法應(yīng)該多久執(zhí)行一次，而不管之前的執(zhí)行需要多長時間......
因此，如果您的示例中的某些代碼在某個時間間隔內(nèi)花費(fèi)的時間比您的固定費(fèi)率多得多，那么連續(xù)的任務(wù)可能剛剛在該時間間隔內(nèi)排隊。一旦完成繁重的執(zhí)行并且如果下一次執(zhí)行恰好是輕量級的，那么您將在日志中看到您在日志中看到的內(nèi)容，直到 ScheduledExecutorService 的隊列被耗盡。之后，您的輕量級任務(wù)將開始以固定速率毫秒運(yùn)行。
嘗試在日志中搜索第一次執(zhí)行以查看它們所花費(fèi)的時間。您還可以注釋掉一些代碼并重新啟動您的應(yīng)用程序以嘗試定位根本原因。下面是我的模擬示例，預(yù)計每 1 秒運(yùn)行一次，但第一次運(yùn)行需要 5 秒：
public class CacheManager {
private static final Logger LOG = LoggerFactory.getLogger(CacheManager.class);
private final AtomicInteger counter = new AtomicInteger();
public void updateConfigurations() throws InterruptedException {
LOG.info("update configurations");
if (counter.getAndIncrement() == 0) {
Thread.sleep(5000);
}
LOG.info("end update configurations");
}
public static void main(String[] args) {
new ClassPathXmlApplicationContext("spring.xml");
}
}
<beans ...>
<bean id="cacheManager" class="CacheManager"/>
<task:scheduler id="ttScheduler" pool-size="1"/>
<task:scheduled-tasks scheduler="ttScheduler">
<task:scheduled ref="cacheManager" method="updateConfigurations" fixed-rate="1000" initial-delay="0"/>
</task:scheduled-tasks>
</beans>
輸出：
21:00:58.703 [ttScheduler-1] INFO CacheManager - update configurations
21:01:03.706 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:03.706 [ttScheduler-1] INFO CacheManager - update configurations
21:01:03.707 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:03.707 [ttScheduler-1] INFO CacheManager - update configurations
21:01:03.707 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:03.707 [ttScheduler-1] INFO CacheManager - update configurations
21:01:03.707 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:03.707 [ttScheduler-1] INFO CacheManager - update configurations
21:01:03.708 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:03.708 [ttScheduler-1] INFO CacheManager - update configurations
21:01:03.708 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:04.707 [ttScheduler-1] INFO CacheManager - update configurations
21:01:04.708 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:05.706 [ttScheduler-1] INFO CacheManager - update configurations
21:01:05.706 [ttScheduler-1] INFO CacheManager - end update configurations
21:01:06.704 [ttScheduler-1] INFO CacheManager - update configurations
21:01:06.704 [ttScheduler-1] INFO CacheManager - end update configurations
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