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
Related
I have a JavaFX application, when the user closes the window, I want to destroy all of the JavaFX related resources and only have a tray icon, where the user can then reopen the application.
I have many background threads running, which should stay running when the GUI is closed. I have tried using Platform.exit() however it has no impact on the RAM usage of the program.
What is the best way to accomplish this? My goal is to reduce the impact on the system from my program as much as possible when the application is closed, but still running all of the background threads.
One option is to run the application as a separate process, launching the process when you want to create the application and exiting the process when the application is no longer needed (so completing a full application lifecycle). That way you will be absolutely sure that the application is not consuming any resources when it is not being used, because it won't be running.
How you would accomplish the launching and any communication between your tray service and the application would be up to you. You can research various mechanisms and, if you decide to go this route, ask some new follow up questions on accomplishing certain aspects of the task.
Some example routes you could look at are the ProcessBuilder, which is admittedly a pretty finicky and horrible API or the new Process API updates that will be available with Java 9. If wish to ensure at most a single instance of the application process is ever used, there are solutions for that. If you need to send a signal to the running application process, you could use something like RMI or run a basic HTTP REST server in your application and send messages into that.
As an aside, years ago there used to be some ongoing work on building multi-process JVMs, but there was never any wide uptake of the idea for Java. Though most modern browser clients, such as Chrome and Firefox, are multi-process architectures, the linked articles give some insight into this architecture, some of the potential implications of it and why it used for those applications.
Before going such a route, I would advise you to ensure that such an approach is truly necessary for your application (as pointed out by user npace in comments).
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 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
What's the best/easiest way to run periodic tasks (like a daemon thread) on a tomcat/jetty server? How do I start the thread? Is there a simple mechanism or is this a bad idea at all?
If want to keep everything on java side, give a look to Quartz.
It handles failover and fine grained repartition of jobs, with the same flexibility of cron jobs.
It's okay and effective to stash a java.util.Timer (or better yet ScheduledExecutor) instance in your ServeletContext. Create it in a Servlet's init() call and all your servlets can add TimerTasks to it.
One general purpose way which works for many systems is simply to have a cron job which performs a periodic wget against your app.
I can't answer the tomcat/jetty stuff, but I've done similar things with Python based web apps.
I normally just run a separate app that does the periodic tasks needed. If interop is needed between the website and the app, that communication can happen through some sort of API (using something like XML-RPC/unix sockets/etc) or even just through the database layer, if that's adequate.
Hope that helps.
If you want to use a cron job but don't have administrative access to the development system, you can do a user crontab by executing the command:
crontab -e
It uses vi by default on most systems, but you can change it to the editor of your choice via:
export EDITOR=/usr/local/bin/my_editor
Then, executing the crontab -e command will launch your crontab file in your editor. Upon saving, the changes will be committed back into the system's cron.
We have a application that should always be running. Does anyone know of a way to create an automated way of monitoring to see if this application is running (possibly using a batch file)? If it is not running, then send an email notification and start the application?
Nagios is generally what's used by systems administrators that I've come across. You can script it to do whatever check you need and alert based on a variety of conditions. Works well with cacti so you can graph stuff too :)
If you want to ensure that your service always restarts should it die you could use supervise from daemontools.
Alternative to Nagios is zabbix
You don't mention an OS but if you're looking for something on Windows, Application Monitor might be a good start.
If you're on Linux, monit look pretty useful.
Most monitoring systems have a built-in test which watches the process list to check that everything that should be running is running.
We use Hobbit, it has a configurable table of processes which should be running (and the number of instances, red/yellow alert etc).
We are now heading to release our service that can do some monitoring tasks that usually are hard to handle by Nagios or other similar tools. We provide instant notifications (email, SMS) when:
a) your application/service does not respond for some time
b) some conditions are met (e.g. time of execution of some part of logic > X, number of emails sent < Y or whatever you want)
This is absoltely easy to use when compared to Nagios or others and it does not require installation. We spent a lot of time to make it user-friendly
As I mentioned this will be released very soon (will come back and give you the information). If you are interested in our approach we invite you to beta tests of our application (there will be some promotion for participants).