I'm learning about quartz scheduler. I want to know how it triggers the job at the specified time?
I want to know how does quartz scheduler works.
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I'm using quartz framework to setup a schedule task in java.
eg: I hope the job will be triggered at 12:00 o'clock from 2022-01-25 to 2022-01-29.
is there any way that I can change the quartz's calendar to a specific date and time to make the schedule job can be triggered immediately?
if today is 2022-01-20, how can I mock current date and time in jvm, rather than bring up my spring boot service and wait, until that day...
thanks for your help.
The easiest way is probably using some of the GUI-based Quartz scheduler managers that let you connect to your Quartz scheduler manually execute arbitrary jobs through a GUI.
Here is an example of how to do that using QuartzDesk (I am biased here), but other tools may work similarly. Even the QuartzDesk Lite (free) edition lets you do that. No application code changes are required.
My entire application's state depends on the quartz scheduler.
I am running a daily job which runs every 24 hours and updates the application state based on the logic written in job's execution function.
While testing, I found that sometimes when the system gets heavily loaded, scheduler do not work and the state does not change.
When I was running scheduler for every second and keeps system heavily loaded I was able to reproduce this case frequently.
Is there any way to ensure that quartz scheduler is running always?
I am using quartz to schedule jobs to be executed daily as a part of a much larger web application. However, after a couple of days, the administrator would like to stop the execution of a particular job (maybe because it is no longer needed). How do I go about doing this? I read the api docs for the Scheduler and it has a method called interrupt(JobKey jobkey) but that method would work only with the same instance of the scheduler that was used to schedule the job.
interrupt(JobKey jobKey)
Request the interruption, within this Scheduler instance, of all
currently executing instances of the identified Job, which must be an
implementor of the InterruptableJob interface.
Is there anyway of getting the instance of an existing scheduler? Or maybe use singletons?
Should definitely use a singleton instance of your scheduler. I recommend the use of an IoC container to manage this in a clean and efficient way.
I'm looking into using Quartz Scheduler, and I was wondering if it was possible to schedule jobs not by time, but when another job finishes. So, when Job A is done, it starts Job B. When that's done, it starts Job C, etc.
Job A -> Job B -> Job C -> Job A... continuously.
Is this the right tool for the job? Or should I be looking into something else?
Check out JobChainingJobListener, built-in to Quartz (bold mine):
Keeps a collection of mappings of which Job to trigger after the completion of a given job. If this listener is notified of a job completing that has a mapping, then it will then attempt to trigger the follow-up job. This achieves "job chaining", or a "poor man's workflow".
That's right, you are looking for a process or workflow engine. Have a look at activiti or jbpm.
You may want to check the QuartzDesk project I have been involved in. QuartzDesk is a management and monitoring platform for Quartz-based apps and in version 2.0 we have added a new job chaining engine to the platform.
The engine allows you to orchestrate the execution of your jobs and there is no need to modify your application code in any way. Job chains can be dynamically updated through the QuartzDesk GUI without any disruption to your application.
I have several web-servers and need them to use Quartz. The clustering feature of Quartz would be ideal, but it requires that the servers clocks are in complete sync. They have a very scary warning about this:
Never run clustering on separate machines, unless their clocks are synchronized using some form of time-sync service (daemon) that runs very regularly (the clocks must be within a second of each other).
I cannot guarantee complete clock synchronization, so instead of using the clustering feature I was thinking to have a single Quartz instance (with a stand-by for fail-over). Having a single instance executing jobs is not a problem, but I still need all of the web servers to be able to schedule jobs.
Can I directly add jobs into the JDBCJobStore from the web servers, and will they be picked up by the (non-clustered) Quartz server? I would be doing this by creating schedule instances in the web servers to add jobs. These instances would never be started, just used to access the JobStore.
Wrote a test program that creates a "non-clustered" Quartz scheduler using the same JobStore as the "real" scheduler (also non-clustered), and schedules jobs. After a few seconds, these jobs do get executed, so it seems to work.
Update: I cross-posted this question to the Quartz forum, and got the answer that this should work. In a related question they state that
The jobs can be inserted into that database by another process by:
1- using the rmi features of quartz from another process, and using the quartz API
2- instantiating a scheduler within another process (e.g. webapp), also pointing it to the same database, but NOT start()ing that scheduler instace, and the using the quartz api to schedule jobs.