I want to use camel->quartz component to schedule some job to be done at specified time interval.
But I want that in synchronized manner. Means, Next execution of scheduled job should only start after completion of current execution.
I created Route and Scheduler Service for Servicemix.
QuartzRoute.java
public class QuartzRoute extends RouteBuilder {
#Override
public void configure() throws Exception {
from("quartz://myGroup/myTimerName?cron=0/1+*+*+*+*+?").process(new SchedulerService());
}
}
SchedulerService.java
public class SchedulerService implements Processor {
public void process(Exchange exchange) throws Exception {
System.out.println("I'm running every 5 sec...");
Thread.sleep(5000);
System.out.println("Exiting iteration ");
}
}
Here, I want "I'm running every 5 sec..." and "Exiting iteration " to be printed in same order every time.
In sort i want this SchedulerService to be executed again only after completion of current execution.
Use the stateful=true option of the quartz component. See Scheduled with fixed delay in quartz scheduler?
"stateful jobs are not allowed to execute concurrently, which means new triggers that occur before the completion of the execute(xx) method will be delayed."
Related
I've the problem, that I want to create a scheduled task during runtime. The scheduled task should be triggered with a fixed rate. But now I'm having the problem that the manual setup schedules are not triggered in an async way.
The main problem is, that we do not have any fix point were we can start the scheduler. It should get created when I read a specific value (1) and gets destroyed when the value changes back (0). Otherwise we could use the annotation configuration described in test 1 below.
What I have tried so far:
1. Schedule with #Scheduled(fixedRate = 500L) and #Async
Code
#Async
#Scheduled(fixedRate = 500L)
public void annotationTest() {
UUID id = UUID.randomUUID();
log.warn("Hello from Thread {} going to sleep", id);
try {
Thread.sleep(1000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
log.warn("Finished Thread {}", id);
}
Also having the #EnableAsync and #EnableScheduling annotations on class level.
Result
09:56:24.855 [task-5] : Hello from Thread 3b5514b2-3b80-4641-bf12-2cd320c4b6e5 going to sleep
09:56:25.355 [task-6] : Hello from Thread e98514a7-e193-422b-9569-f7635deb33f8 going to sleep
09:56:25.356 [task-4] : Finished Thread d86f5f24-bffb-4ddd-93fe-2334ed48cf91
09:56:25.854 [task-7] : Hello from Thread cfc2ab03-4e7e-4a4a-aa08-41d696cb6df7 going to sleep
09:56:25.855 [task-5] : Finished Thread 3b5514b2-3b80-4641-bf12-2cd320c4b6e5
09:56:26.355 [task-6] : Finished Thread e98514a7-e193-422b-9569-f7635deb33f8
Comment
This works as expected, but we are not able to use it, because we have to create the scheduler during runtime and destroy it after a specific time/input.
2. Setting up a ScheduledTaskRegistrar
Code
//#Configuration
#Bean
public ScheduledTaskRegistrar scheduledTaskRegistrar() {
ScheduledTaskRegistrar scheduledTaskRegistrar = new ScheduledTaskRegistrar();
scheduledTaskRegistrar.setScheduler(threadPoolTaskScheduler());
return scheduledTaskRegistrar;
}
#Bean
public TaskScheduler threadPoolTaskScheduler() {
ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
scheduler.setPoolSize(20);
return scheduler;
}
//#Component
public void printMessages() {
scheduledTaskRegistrar.scheduleFixedRateTask(new FixedRateTask(new OwnRunnable(), 500L, 0L));
}
The OwnRunnable will also sleep 1 second and print the finish Text afterwards
Result
10:13:56.983 [TaskScheduler-1] : Finished Thread 73f70de9-35d9-47f0-801b-fb2857ab1c34
10:13:56.984 [TaskScheduler-3] : Hello from Thread 7ab16380-8dba-49e1-bf0d-de8235f81195 going to sleep
10:13:57.984 [TaskScheduler-3] : Finished Thread 7ab16380-8dba-49e1-bf0d-de8235f81195
10:13:57.984 [TaskScheduler-2] : Hello from Thread cc152d2e-f93b-4770-ac55-853a4dd6be97 going to sleep
10:13:58.985 [TaskScheduler-2] : Finished Thread cc152d2e-f93b-4770-ac55-853a4dd6be97
10:13:58.985 [TaskScheduler-4] : Hello from Thread 8d4510a4-773d-49f3-b51b-e58e425b0b68 going to sleep
Comment
As we can see the tasks run in a synchronous way and will not fit to our requirement.
3. Other tests
All other tests are similar to the test described in 2 but will use some other configurations of the ScheduledTaskRegistrar. The results are the same as in test 2.
ConcurrentTaskScheduler instead of ThreadPoolTaskScheduler
ConcurrentTaskScheduler with SimpleAsyncTaskExecutor as ConcurrentExecutor
ConcurrentTaskScheduler with ThreadPoolTaskExecutor as ConcurrentExecutor
Question(s)
How can I use the configuration described in test 2 but get the result of test 1? Is there a way to use the #Async annotation with solution described in test 2? Or does anyone have a better/ another solution for my problem?
Yes, it is possible. Assume that your class that implemented SchedulingConfigurer has a method, doMyJob(). You can annotate that method with Async and use the reference in FixedRateTask. Also notice the class level annotation
#Configuration
#EnableAsync
public class MyJobConfig implements SchedulingConfigurer {
#Override
public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
taskRegistrar.scheduleFixedRateTask(new FixedRateTask(this::doMyJob, 500L, 0L));
}
#Async
public void doMyJob() {
try {
Thread.sleep(1000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
Hope it helps
EDIT
I provided the code without testing. Recently when I tried to recreate this scenario, I noticed that if doMyJob is within SchedulingConfigurer, it will not be truly async (if delay is 5seconds and job takes 10seconds, next job runs only after 10seconds). But moving the method to a service class helped.
I'm using Java and I want to keep a servlet continuously running in my application, but I'm not getting how to do it. My servlet has a method which gives counts of the user from a database on a daily basis as well as the total count of the users from the whole database. So I want to keep the servlet continuously running for that.
Your problem is that you misunderstand the purpose of the servlet. It's intented to act on HTTP requests, nothing more. You want just a background task which runs once on daily basis.
EJB available? Use #Schedule
If your environment happen to support EJB (i.e. a real Java EE server such as WildFly, JBoss, TomEE, Payara, GlassFish, etc), then use #Schedule instead. Here are some examples:
#Singleton
public class BackgroundJobManager {
#Schedule(hour="0", minute="0", second="0", persistent=false)
public void someDailyJob() {
// Do your job here which should run every start of day.
}
#Schedule(hour="*/1", minute="0", second="0", persistent=false)
public void someHourlyJob() {
// Do your job here which should run every hour of day.
}
#Schedule(hour="*", minute="*/15", second="0", persistent=false)
public void someQuarterlyJob() {
// Do your job here which should run every 15 minute of hour.
}
#Schedule(hour="*", minute="*", second="*/5", persistent=false)
public void someFiveSecondelyJob() {
// Do your job here which should run every 5 seconds.
}
}
Yes, that's really all. The container will automatically pickup and manage it.
EJB unavailable? Use ScheduledExecutorService
If your environment doesn't support EJB (i.e. you're not using not a real Java EE server, but a barebones servletcontainer such as Tomcat, Jetty, etc), then use ScheduledExecutorService. This can be initiated by a ServletContextListener. Here's a kickoff example:
#WebListener
public class BackgroundJobManager implements ServletContextListener {
private ScheduledExecutorService scheduler;
#Override
public void contextInitialized(ServletContextEvent event) {
scheduler = Executors.newSingleThreadScheduledExecutor();
scheduler.scheduleAtFixedRate(new SomeDailyJob(), 0, 1, TimeUnit.DAYS);
scheduler.scheduleAtFixedRate(new SomeHourlyJob(), 0, 1, TimeUnit.HOURS);
scheduler.scheduleAtFixedRate(new SomeQuarterlyJob(), 0, 15, TimeUnit.MINUTES);
scheduler.scheduleAtFixedRate(new SomeFiveSecondelyJob(), 0, 5, TimeUnit.SECONDS);
}
#Override
public void contextDestroyed(ServletContextEvent event) {
scheduler.shutdownNow();
}
}
Where the job classes look like this:
public class SomeDailyJob implements Runnable {
#Override
public void run() {
// Do your daily job here.
}
}
public class SomeHourlyJob implements Runnable {
#Override
public void run() {
// Do your hourly job here.
}
}
public class SomeQuarterlyJob implements Runnable {
#Override
public void run() {
// Do your quarterly job here.
}
}
public class SomeFiveSecondelyJob implements Runnable {
#Override
public void run() {
// Do your quarterly job here.
}
}
Do not ever think about using java.util.Timer/java.lang.Thread in a Java EE / Servlet based environment
Last but not least, never directly use java.util.Timer and/or java.lang.Thread in Java EE. This is recipe for trouble. An elaborate explanation can be found in this JSF-related answer on the same question: Spawning threads in a JSF managed bean for scheduled tasks using a timer.
I would suggest using a library like quartz in order to run the task at regular intervals. What does the servlet really do ? It sends you a report ?
You can use cron4j. http://www.sauronsoftware.it/projects/cron4j/manual.php
Implement two classes and call startTask() in main.
public void startTask()
{
// Create a Runnable
Runnable task = new Runnable() {
public void run() {
while (true) {
runTask();
}
}
};
// Run the task in a background thread
Thread backgroundThread = new Thread(task);
// Terminate the running thread if the application exits
backgroundThread.setDaemon(true);
// Start the thread
backgroundThread.start();
}
public void runTask()
{
try {
// do something...
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
In a production system that may have multiple non-jee containers running. Use anot enterprise scheduler like Quartz scheduler which can be configured to use a database for task maamgememt.
I have a thread which executes code periodically, e. g. every 10 seconds. I'd like to have the option to also invoke the same code in a spontaneous way and not have to wait 10 seconds. But the code of the automatic and spontaneous execution must never run concurrently, instead they should run in sequence if the user presses the execute button while the thread is invoking the same method.
Does anyone know a good pattern or even a class that can address this kind of requirement?
First thing that comes to mind would be to make the work method synchronized. But in that case the manual execution (e. g. button press) is blocked and has to wait until the method in the thread is finished. Is there a better approach without blocking?
Example:
public class Executor extends Thread {
// endless loop, executes work method periodically with pause inbetween
#Override
public void run() {
while( true) {
work( "automatic");
pause(10000);
}
}
// Working method that's executed periodically or manually
private synchronized void work( String text) {
System.out.println( "Working " + text + " " + System.currentTimeMillis());
}
// helper method that pauses the thread
private static void pause( long sleepMs) {
try {
Thread.sleep(sleepMs);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
// start automatic execution
Executor executor = new Executor();
executor.start();
// pause a while
pause(1000);
// manual execution
executor.work( "manual");
}
}
Edit: Solution for my requirement:
public class ScheduledExecutor {
public static void main(String[] args) throws InterruptedException {
ScheduledThreadPoolExecutor executor = (ScheduledThreadPoolExecutor) Executors.newScheduledThreadPool(1);
executor.scheduleWithFixedDelay(new Work("auto"), 0, 10, TimeUnit.SECONDS);
Thread.sleep(1000);
executor.execute(new Work("manual"));
}
public static class Work implements Runnable {
String text;
public Work(String text) {
this.text = text;
}
#Override
public void run() {
System.out.println("Working " + text + " " + System.currentTimeMillis());
}
}
}
I would create a new, single-thread executor service:
ExecutorService executorService = Executors.newFixedThreadPool(1);
Then, I would set up a timer that feeds the executorService a task once every 10 seconds.
new Timer(10000, new ActionListener {
public void actionPerformed(ActionEvent evt) {
executorService.execute(() -> doWhatever());
}
}).start();
Finally, you can call executorService.execute(() -> doWhatever()); in your button press handler, or wherever else you want in your code.
Only one activation of doWhatever() will run at a time because the executorService has only one thread on which to run them. And, your button press handler will never have to wait, because it does nothing but put a new object on a queue.
I have a thread which executes code periodically, e. g. every 10 seconds. I'd like to have the option to also invoke the same code in a spontaneous way and not have to wait 10 seconds.
A simple way to do this in your code is not to pause by using Thread.sleep(...) but rather do wait(...). Then whenever you want the command to wakeup and run manually it just does a notify().
So you code would look something like:
while( true) {
work( "automatic");
synchronized (this) {
try {
// wait for a bit but allow someone else to awake us to run manually
wait(10000);
} catch (InterruptedException ie) {
// always a good pattern
Thread.currentThread().interrupt();
return;
}
}
}
Then when you want to have it run manually you do:
synchronized (executor) {
executor.notify();
}
The notify will awaken the thread immediately so that it can run it's task. The work method then does not need to be synchronized because only the Executor thread is running it.
NOTE: As pointed out by #shinobi, using wait() like this could suffer from spurious wake-ups which can happen with certain OS thread implementations.
Lastly, it is a better practice to make Executor implement Runnable as opposed to extending Thread.
Share a semaphore between the server thread (the one that executes the task) and client threads (the ones that need to trigger immediate execution):
Semaphore sem = new Semaphore( 0 );
The server thread needs to execute the following code (note that it's an endless loop — you'll likely want to plug-in your program termination check as the condition to while()):
while( true ) {
try {
sem.tryAcquire( 10, TimeUnit.SECONDS );
} catch( InterruptedException e ) {
continue;
}
runTask();
sem.drainPermits();
}
Then, in order to trigger immediate execution, the client thread needs to do:
sem.release();
Thus, the server thread will execute the task upon either acquiring a permit from the semaphore as soon as a client thread releases one (triggered immediate execution,) or timing-out in Semaphore.tryAcquire() (periodic executions 10s apart, end-to-start.) Having executions 10s apart start-to-start will take some slightly more involved logic, as well as keeping track of last execution's starting time, but the basic idea remains the same.
You need to drain the permits each time in order to avoid multiple back-to-back executions of the task, in cases where it might be triggered for immediate execution while still being executed.
My aim is to create a queue system where I can specify a maximum amount of concurrent jobs for each group, i.e. for group A maximum 3 jobs should run at the same time, for group B max Y jobs etc. The jobs can be executed both on cron schedule and only once with SimpleTrigger, therefor I can't check the queue when scheduling the job, I have to check it before or during execution. I'm implementing a joblistener and I'm trying to prevent execution in the jobToBeExecuted() method. I've tried scheduler.interrupt() but it doesn't work when the job hasn't started yet. scheduler.deletejob() and scheduler.unschedule() didn't stop it from executing either.
Any ideas?
public class JobQueueListener implements JobListener {
#Override
public void jobToBeExecuted(JobExecutionContext context) {
JobKey currentJobKey = context.getJobDetail().getKey();
JobDetail jobDetail = context.getJobDetail();
Scheduler scheduler = context.getScheduler();
if (shouldBePutInQueue(currentJobKey)) {
/// Prevent execution and put in queue here, but how?
}
}
#Override
public void jobWasExecuted(JobExecutionContext context, JobExecutionException jobException) {
//Check queue and execute next in queue
}
}
Can you look at TriggerListener
You should implement TriggerListener and have your abort logic within "vetoJobExecution" method.
boolean vetoJobExecution(Trigger trigger,
JobExecutionContext context)
Its Called by the Scheduler when a Trigger has fired, and it's associated JobDetail is about to be executed. If the implementation vetos the execution (via returning true), the job's execute method will not be called.
I have an application with a few different, long running quartz jobs. Every job is triggered by a kind of event (for example user action) and it is intended to run only once per such an event. In the environment where the application works the following scenario happens...
Application is running,
Long running job is triggered,
During the execution of the job application shutdown occurs,
Application is starded again.
Is it possible to cause that quartz will automatically refire the job started and not finished previously (in the previous session of the application)? I mean using jdbc job store, which works well for misfired jobs - but is it possible to refire not finished job.
This is the best approach I've found:
Configure quartz scheduler with:
org.quartz.scheduler.interruptJobsOnShutdownWithWait=true
Make your recoverable jobs implementing InterruptableJob, and manually trigger the current job as part of interrupt logic (example below).
Write your own ShutdownHook to call Scheduler.shutdown(true) or use quartz ShutdownHookPlugin
This way, when an ordered shutdown is detected by the VM (hard shutdowns bust be handled by RequestRecovery: quartz jobDetail requestRecovery), jobs implementing InterruptableJob will be interrupted and re-triggered. This trigger will not occur until next start.
There is a quick example of how to implement:
public static class TriggerOnInterruptJob implements InterruptableJob {
private boolean interrupt = false;
#Override
public void execute(JobExecutionContext context) throws JobExecutionException {
LOGGER.debug("START");
synchronized (mutex) {
mutex.notifyAll();
}
executionCount.incrementAndGet();
try {
while (!interrupt)
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
context.getScheduler().triggerJob(context.getJobDetail().getKey());
} catch (SchedulerException e) {
e.printStackTrace();
}
}
#Override
public void interrupt() throws UnableToInterruptJobException {
interrupt = true;
}
}