[NIFI-3242] CRON scheduling can occur twice for the same trigger

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.7.0
• Assignee: Unassigned
• Reporter: Joe Percivall
• Created: 21/Dec/16 19:01
• Updated: 14/Jun/18 14:12
• Resolved: 14/Jun/18 14:12

Description

Initially brought up in this message[1] to the user list.

The logic for CRON scheduling is done here[2]. The CRON expression is evaluated and used to check when to schedule the next trigger[3]. I believe problems arise due to the approximate nature of the java scheduler and potentially the millisecond portion of quartz scheduler getting wiped here[4] can lead to the behavior seen in the mailing list (an extra invocation right before the correct time).

[1] http://mail-archives.apache.org/mod_mbox/nifi-users/201612.mbox/%3C1482106268095-481.post%40n4.nabble.com%3E
[2] https://github.com/apache/nifi/blob/c10d11d378ffd7c3044446830e24d50c5befc98a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core/src/main/java/org/apache/nifi/controller/scheduling/QuartzSchedulingAgent.java#L177-L177
[3] https://github.com/apache/nifi/blob/c10d11d378ffd7c3044446830e24d50c5befc98a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core/src/main/java/org/apache/nifi/controller/scheduling/QuartzSchedulingAgent.java#L180
[4] https://github.com/quartz-scheduler/quartz/blob/quartz-2.2.1/quartz-core/src/main/java/org/quartz/CronExpression.java#L1170

Issue Links

• is duplicated by: NIFI-3271 GenerateFlowFile processor creates duplicates with CRON scheduling strategy and Primary node only execution
• links to: GitHub Pull Request #2789