I have a java application (jar file) and I want to add some sort of scheduling option in it. This means that the application will offer users the ability to carry out a particular job automatically in intervals as defined by the users themselves. I was thinking of calling the scheduler from the command line (through Java code), such as using the 'AT' command for Windows and Anacron for UNIX-based systems.
My first part of the question is about the 'AT' command in Windows:
I have tried using the 'AT' command from the command line directly however I can't seem to get it to work. The job is listed as a scheduled task, however when the time elapses the task is not executed. (The task that I'm trying to run is a jar file which runs perfectly normal when I run it from the command line without the scheduling.) Would anyone be kind enough to point out anything that I might be doing wrong? The command I am supplying is as follows:
'AT XX:XX java -jar C:....\xyz.jar' ,where XX:XX is the time that I want to run it at.
The second part of the question is about any other different implementations of such functions:
I am open for ideas, so if there is a different way of implementing such a function please do not hesitate to mention it. The implementation has to be cross-platform and if possible, free.
Really only an answer to the second part of your question, but you might want to take a look at Quartz Scheduler.
You can also potentially use a framework like Spring that supports Quartz to simplify and understand the usage further Quartz Scheduling with Spring.
you need check "Task Scheduler" service is started and add FULL path to java
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I have situation where I start JDK18 jvm from c++ code to produce vst plugin goal being to implement audio signal algorithms in java side with added value of full java GUI api. My framework works very smoothly apart from the repeatable state where my audio streaming crashes after 14 hours. So I thought this is good place to start learning JFR. My jvm starting parameters are in xml file and relevant part is:
<param>
-XX:StartFlightRecording,dumponexit=true,filename=c:/out/blackbox.jfr
</param>
Even when application exits that named file keeps empty. So what is the idea of filename parameter if it stays empty and how to use it?
The recording is dumped in a Java shutdown hook. If you terminate the C++ application with exit(status), the Java hook never gets a chance to run.
Not sure how to best run the shutdown hooks, but you could perhaps invoke System.exit(status) from native using CallStaticVoidMethod?
My solution with JDK 18 and flight recorder is not to use JVM startup options at all but instead use jcmd's JFR commands. This is due to incompatible JVM options at startup and lacking documentation. Available documentation is clearly for some older versions of JVM. Here is the available documentation:https://docs.oracle.com/javacomponents/jmc-5-5/jfr-command-reference/toc.htm which proposes use of -XX:+UnlockCommercialFeatures which has been long gone. What is current state of command line options is not achieveable for average programmer.
But "jcmd JFR.start" is example of things that work. I got things working observing with "jcmd PID JFR.check" . It is obvious that JFR api is also little bit broken and needs to addressed in a certain way to get the wanted results. There must have been very hurry when implementing it because the order of parameters is very crucial. And there is a nag that "name" must not be a number even it uses it as number. Now I know it is sensitive. So the way I want it to function is to sample and dump periodic chunks so that differences reveal them selves. Now I have the solution to that but it needs another question with no stupid complaints. Baseline is that jcmd with JFR parameter must be used as it comes out of the box in the way which is not obvious.
I want run a background process at a specific time. I want that process to be run on the server even without running the application from End-User side. The application is made using Spring. Please suggest how to approach for it.
Thanks and regards
Souvik
I depends highly on what platform you are working on, and what you want to achieve.
If it is a simple application, that you simply want to invoke that on specific time, then you can use scheduling tools available on your platform, for example, crontab for Unix, or scheduled task (at) for Windows.
If you want the application to be run as a daemon process, and the application itself will handle the scheduling, then you need to solve two problem: 1. create a daemon process (aka system service), and 2. doing scheduling in Java.
For problem 1, there are already answer for it. Just have a search on Google on "Java System Service" will give you some other useful tools too, like Java Service Wrapper
For problem 2, there are a lot of way to perform scheduling in Java. You can do it by built-in Timer etc, or using scheduling library like Quartz
I have a .bat file in a Windows machine that starts our program by calling a main class of a Java executable(.Jar)
Now I need to run this every 30 mins.
I gone through several ways of doing it, but unable to decide which is better.
Scheduling through Windows scheduler or Using Java Timer. Which one to choose?
I want only one instance of the process running. If the previous process doesnt complete within 30min, i could wait.
Please let me know what to go for, based on my use case.
Thanks in advance.
You're better off using the Windows Scheduler. If there's a real risk of the process taking too long, you can create a file, or open a socket while the process is running and when another one tries to start up, it can detect that and simply quit. This would make it "miss" the 30m window (i.e. if the first job started at 12 and finished at 12:35, the next job would not start until 1).
But this way you don't have to worry at all about setting up long running processes, starting and stopping the java service, etc. The Windows scheduler just makes everything easier for something like this.
TimerTask is not a scheduling system, it is a library that provides tools for in-app scheduling. Seems that for your use-case you need a the system: you need it to run whether or not your app is running, you need reporting, etc. Windows Scheduler (or cron on unix/linux) is more appropriate for your needs.
I'm developing an application which requires Contents of the database to be written to an ms-excel file at the end of each day. I've written the code for copying the contents into ms-excel file but Now how to proceed further? Whether threads are to be used to check for the completion of 24 hours or there's some other mechanism? Please provide me some guidance.
If you need to facility to run things at set times during the day, you should consider the Quartz Scheduler. It might be overkill, but it's very capable.
For example, you can use its CronTrigger to configure a job to run on a schedule defined by a cron expression, e.g. 0 23 55 * * ? (or something like that) would run your job at 5 to midnight every night (see examples).
Quartz recently got a boost to its future and fortunes by being acquired by the Terracotta folks. Hopefully it'll get some real active development now.
I agree with the others that using something like crontab would be better. However, if you can't do that, I would use the java.util.concurrent package added in Java 1.5. The class you would need is ScheduledThreadPoolExecutor. Specifically, the scheduleAtFixedRate() method.
I think that from the design perspective it is better to use crontab on linux platform or task scheduler on windows platform. It will keep your java program small, and simple. While the solution with thread waiting for the specific time seems simple it will add one serious concern - you will have to monitor its health.
In addition - I would suggest to carefully plan logs your job is writing each time it is run. It is important to have logs for both successful and unsuccessful runs.
It makes sense to make separate file for such logs.
One more case to be considered - what to do if database was not available exactly in the time when job run? Is it acceptable to wait another 24 hours?
I have a Virtual Dedicated Server, how can I run an application periodically (ie: every Monday - 19:00). I mean, the application starts automatically at a given time.
Is there any way to do it with Java, Ajax, PHP? (sorry, I'm noob)
You can create scheduled tasks in windows and cron jobs in linux/*nix like systems. If you can run programs on the server and want to use java you can use timers to schedule your task - here is a simple example.
I'm assuming your server is linux.
You may be able to do this with webmin.
You will need to use command line to install webmin and setting up a crontab from command line is really not that hard to do.
Here is a tutorial for crontab.
http://www.linuxweblog.com/crotab-tutorial
What OS does the server run?