Ensure that Spring Quartz job execution doesn't overlap

Question

I have a Java program that executes from Spring Qquartz every 20 seconds. Sometimes it takes just few seconds to execute, but as data gets bigger I\'m sure it run for 20 sec

Answer 1

put them in a queue

Even if the time exceeds 20 second current job should be finished & then the next should be fetched from the queue.

Or you can also increase time to some reasonable amount.