[GitHub] [activemq-artemis] franz1981 commented on pull request #3287: ARTEMIS-2926 Scheduled task executions are skipped randomly

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franz1981 commented on pull request #3287:
URL: https://github.com/apache/activemq-artemis/pull/3287#issuecomment-717082441


   @gemmellr 
   
   A couple of observations on the changes on be3c193 on https://github.com/apache/activemq-artemis/blob/be3c193f73775b961f855e6d935c442e28a14875/artemis-commons/src/main/java/org/apache/activemq/artemis/core/server/ActiveMQScheduledComponent.java#L324-L331
   I've chosen on purpose to allow a racing booking request (can be either from a `delay` or the next periodic task submission on `executor`) to happen before instead of on completion of `ActiveMQScheduledComponent.this.run()`:
   
   - because of the expected behaviour of `delay`: 
   eg `JDBCJournalImpl` submit some records and call `syncTimer.delay()`; it means that if a pending task hasn't yet hit`bookedForRunning.compareAndSet(true, false)`, the delay request will fail, leaving some records to not be picked up and processed later
   - because of the uselessness (due to how a JVM work?) to detect a "slow" (ie which execution time is > period) pending task (see https://issues.apache.org/jira/browse/ARTEMIS-2926?focusedCommentId=17212908&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17212908): TLDR if `bookedForRunning.compareAndSet(true, false)` takes long time to be hit it doesn't mean that the task hasn't been prompty executed/is slow -> skipping the next period task just means we're slowing down rate!


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