I have a building block which sets up a Quartz job to send out emails every morning. The job is fired three times every morning instead of once. We have a hosted instance of Blackboard, which I am told runs on three virtual servers. I am guessing this is what is causing the problem, as the building block was previously working fine on a single server installation.
Does anyone have Quartz experience, or could suggest how one might prevent the job from firing multiple times?
Thanks,
You didn't describe in detail how your Quartz instance(s) are being instantiated and started, but be aware that undefined behavior will result if you run multiple Quartz instances against the same job store database at the same time, unless you enable clustering (see http://www.quartz-scheduler.org/docs/configuration/ConfigJDBCJobStoreClustering.html).
I guess I'm a little late responding to this, but we have a similar sort of scenario with our application. We have 4 servers running jobs, some of which can run on multiple servers concurrently, and some should only be run once. As Will's response said, you can look into the clustering features of Quartz.
Our approach was a bit different, as we had a home-grown solution in place before we switched to Quartz. Our jobs utilize a database table that store the cron triggers and other job information, and then "lock" the entry for a job so that none of the other servers can execute it. This keeps jobs from running multiple-times on the servers, and has been fairly effective so far.
Hope that helps.
I had the same issue before but I discovered that I was calling scheduler.scheduleJob(job, trigger); to update the job data while the job is running which is randomly triggered the job 5-6 times each run. I had to use the following to update the job data without updating the trigger scheduler.addJob(job, true);
Related
I'm wanting to setup an ECS task to schedule various other application tasks.
The "tasks" this task will schedule will mostly involve calling restful endpoints in another load balanced service.
I know there are other ways to do this, using cloudwatch to trigger a lambda etc. However this seems overly complex for what I need.
I was planning to just make a very simple, light-weight apline based image with a crontab to do the triggering of the restful calls.
This all seems easy enough. The only concern I have is that I would want to prevent, as far as possible, having multiple instances of this task running, even if only for a short period of time.
If my CI/CD pipeline triggers an update to this cron task, then there may be a short period of time, where the old and new task will be running simultaneously.
There may therefore be a small chance that a cron task could be triggered twice.
What I would like to do, is to have ECS stop the currently running task completely, before attempting to start the new one.
This seems to be contrary to the normal way it wants to work, where it will ensure the new task is up, and healthy before stopping the old one.
Is this possible, and if so, how do I configure it?
It's not a problem if my crons don't run for a period of time, but it could be a problem if any get triggered more than once.
Instead of using ECS Service (which makes sure a particular number of tasks is always running and deploys via rolling or B/G deploy strategy which is not you desire) - how about using StopTask and RunTask api to control when a task is stopped and started - gives you complete control.
Instead of using scheduled tasks, you could create an ECS service and use scheduled scaling to scale the desired service count to 1 and back down to zero.
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 have a requirement to generate certain reports as and when the DB is updated (say new alerts have been generated or new users have been created etc). I have MySQL DB triggers that get fired when the tables get updated and my question is can I schedule a job that gets executed whenever the DB trigger fires off?
This is Java Spring based application and I am considering Quartz but so far I haven't been able to figure out if Quartz can trigger jobs based on DB triggers. I have come across a 'jBatchEngine' that says "In contrast to time driven schedulers like Cron, jBatchEngine is event driven". Has anyone done such event-based job scheduling with Quartz or any other tools? Please advise !!
Thanks much !!!
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.
I have to move an SAP background job (ABAP report for A/P) into Cronacle and can't figure out how to stop the job in SAP so I can start running it with the Cronacle schedule.
The job runs in SAP from user SAPSYS every morning at 7:15am, but if you look it up with sm37 there is no time scheduled for it and it's not triggered by an event; also, it's status is SCHEDULED.
I had our Cronacle team search by job number but they couldn't find any scripts pointing to that job. If you look at the finished job it shows that it's scheduled daily for 7:15am. Also, there is no predecessor or successor jobs listed. Is it possible it's being started from another job? How do I find out without deleting this one?
Some suggestion.
If you don't want to delete the scheduled job. try to rename it, and see if it still runs.
Make sure that the users you are using for sm37 has full authorization for the backround administration.
A previous job can schedule and release and create and whatever a new job. Look at what is running before the problematic job.
Look deeply at the dev traces. They somtimes hints about what is going on in the system.
In addtion to a previous job creating the new job explicitly it is also possible that the job is created manually by an ABAP program that is scheduled in another job. Doing a where-used on the function module OPEN_JOB and looking for Z* or Y* programs may give you a hint.
Another thing: Is this scheduled job ever actually excecuted (i.e. are there any previous "FINISHED" jobs with the same name). A Scheduled job will not run unless it is first released. So if it never runs it may be obsolete.
Thanks for the responses! It turned out to be a case of "newbie ignorance." When using SM37 to view the job I neglected to extend the search date to the next day. I don't know why it doesn't show the released job for the current day, but extending it to the next day showed it. That's a lesson I won't forget!