Now, aside from “how many can I store?” is the question of “how many jobs can Quartz be running at the same moment in time?”
One thing that CAN slow down quartz itself is using a lot of listeners (TriggerListeners, JobListeners, and SchedulerListeners). The time spent in each listener obviously adds into the time spent “processing” a job’s execution, outside of actual execution of the job. This doesn’t mean that you should be terrified of using listeners, it just means that you should use them judiciously – don’t create a bunch of “global” listeners if you can really make more specialized ones. Also don’t do “expensive” things in the listeners, unless you really need to. Also be mindful that many plug-ins (such as the “history” plugin) are actually listeners. The actual number of jobs that can be running at any moment in time is limited by the size of the thread pool. If there are five threads in the pool, no more than five jobs can run at a time. Be careful of making a lot of threads though, as the JVM, Operating System, and CPU all have a hard time juggling lots of threads, and performance degrades as the
