Schedule task after certain time when another task finishes execution - java

I am working on spring framework based application.
I have a requirement in which when user logs in to the system, then after certain time gap say 2 minutes or 5 minutes(which should be configurable), another task will start its execution. After that execution completed, result will be published on UI.
So, can anyone tell me the way to implement this in Spring framework.

I do not know if there is a specific way to do it in Spring.
I usually exploit the JAVA SE 7 interface ScheduledExecutorService
There are a lot of samples on the web.
One of them is here.

Related

spring scheduler after maintenance

we are using spring sceduler using
#Scheduled(cron = "0 15 10 15 * ?")
the problem is that some time we have maintenece and the system is down when the job is sceduled to run.
is there another sceduler we can use ? maybe a parameter that checks if there was scedualed job that didnt run during maintenence and run it when the system is up?
or a recomenation for a different scedualer to use
Thanks
M. Deinum mentioned Quartz as a possible solution. It is a very advanced scheduling product that may handle scheduling for multiple nodes insuring that the job would run only on one node. It has many other features. I haven't used it in long while so you can look up if it is something you want to use.
However, I have dealt with your particular case in a simpler way. Part of the scheduled job responsibility was upon each run to write down into a DB table the last scheduled time (the one in the past that triggered the current run), the next scheduled time and the actual last execution time. Then, after a down time when the server starts up it has to check if the next scheduled time is in the past (also the last execution time will be older then the next scheduled time). If it is so, it is your flag that the the job missed its running due to down time (or any other reason). So you can reschedule or run it now
P.S. This will not address your actual problem, but I wrote my own scheduler and published it as part of an open-source library. My scheduler allows you to set the time intervals in more human readable form such as "4h" for 4 hours or "30m" for 30 minutes and so forth. Also it can handle multiple tasks scheduling and allows you to specify the number of threads that will handle all your scheduled tasks. You can read about it here. The library is called MgntUtils and you can get it as Maven artifacts or from Github repository releases (with source code and Javadoc included). You can read an article about the library that describes some of the features here

Getting Started With Real Time Event Scheduling in Java on Linux?

I'm working on a project that will record data on real time events using Java on a linux system.
I have all of the HTML scraping stuff down, that's fine, what I need to figure out is the scheduling and management of the tasks.
There are potentially up to forty events occurring each week, at varying times and events can last up to three hours.
I can create and update the calendar of these events at will, my problem is how to:
Schedule a process to scrape each event at the right time, and update the schedule if there's a change.
Ensure once the scrape process has begun that it stays running for the entire (indeterminate) duration of the event.
Can anyone advise how best to approach this? I'm not sure where I need to start.
Thanks!
a) Schedule a process to scrape each event at the right time, and
update the schedule if there's a change.
If you do not want to use a library, a good starting point for scheduling your tasks can be ScheduledExecutorService. Though you may find other scheduling frameworks useful for your problem out of which Quartz can specifically give you a flexibility in how to schedule the next task based on the current schedule execution results; it also provides a cron capability so that if your schedule is fixed, you can take advantage of a fixed scheduled calendar.
b) Ensure once the scrape process has begun that it stays running for
the entire (indeterminate) duration of the event.
Assuming that you're using a library for HTML scraping, you don't need to ensure it's running since it will be Java task object initiated from your application.

What framework to use for advanced job scheduling in Java?

In my application I need to have periodically run background tasks (which I can easily do with Quartz - i.e. schedule a given job to be run at a specific time periodically).
But I would like to have a little bit more control. In particular I need to:
have the system rerun a task that wasn't run at its scheduled time (i.e. the server was down and because of this the task was not run. In such a situation I want the 'late' task to be run ASAP)
it would be nice to easily control tasks - i.e. run a task on demand or see when a given task was last run or reschedule a given task to be run at a different time
It seems to me that the above points can be achieved with Spring Batch Admin, but I don't have much experience in this area yet. Also, I've seen numerous posts on how Spring Batch is not a scheduling tool so I'm becoming to have doubts what the right tool for the job is here.
So my question is: can the above be achieved with Spring Batch Admin? Or perhaps Quartz is enough but needs configuring to do the above? Or maybe I need both? Or something else?
Thanks a lot :)
Peter
have the system rerun a task that wasn't run at its scheduled time
This feature in Quartz is called Misfire Instructions and does exactly what you need - but is a lot more flexible. All you need is to define JDBCJobStore.
it would be nice to easily control tasks - i.e. run a task on demand or see when a given task was last run or reschedule a given task to be run at a different time
You can use Quartz JMX to access various information (like previous and next run time) or query the Quartz database tables directly. There are also free and commercial management tools basex on the above input. I believe you can also manually run jobs there.
Spring Batch can be integrated with Quartz, but not replace it.

How to do "massive" Job Scheduling (Quartz?)

I have a general question related to the quartz scheduling framework:
I need to perform a task after a fixed amount of time after a user registration. For the sake of simplicity let's say exactly 1 hour after registration of a user in my system. The job MUST be done, even if the system is restarting during this one hour the task must be remembered and it MUST be performed later if my system is down at the usual time.
Is this something where I can or where I would use Quartz? I looked at persistent jobs which looks quite promising but I am not sure if this will still work out for 1000 jobs a day. Furthermore, I am not sure about the performance implications. Maybe someone can help me with information here.
If Quartz is not the right choice, which other ways/frameworks do you see for this issue? My application is a Java 6/Spring 3 based Web-App.
Thanks for your help!
We are using quartz persisted job store successfully in our production environment for a SaaS platform application where 100s of jobs are running.

Concurrent database access pattern for web applications

I'm trying to write a Spring web application on a Weblogic server that makes several independent database SELECTs(i.e. they can safely be called concurrently), one of which takes 15 minutes to execute.
Once all the results are fetched, an email containing the results will be sent to a user list.
What's a good way to get around this problem? Is there a Spring library that can help or do I go ahead and create daemon threads to do the job?
EDIT: This will have to be done at the application layer (business requirement) and the email will be sent out by the web application.
Are you sure you are doing everything optimally? 15 minutes is a really long time unless you have a gabillion rows across dozens of tables and need a heckofalot of joins....this is your highest priority -- why is it taking so long?
Do you do the email job at set intervals, or is it invoked from your web app? If set intervals, you should do it in an outside job, possibly on another machine. You can use daemons or the quartz scheduler.
If you need to fire this process off from the web app, you need to do it asynchronously. You could use JMS, or you could just have a table into which you enter a new job request, with daemon process that looks for new jobs every X time period. Firing off background threads is possible, but its error prone and not worth the complication, especially since you have other valid options that are simpler.
If you are asking about Spring support for long-running, possibly asynchronous tasks, you have a choice between Spring JMS support and Spring Batch.
You can use spring quartz to schedule the job. That way the jobs will run in the same container but will not require an http request to trigger them.

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