Java stop executor service once one of his assigned tasks fails for any reason
The idea is that the tasks are pushing to a common object TaskCompleteEvent. If they push an error the scheduler is stopped and all the tasks will stop.
You can check the results of every task-iteration in the maps "errors" and "success".
public class SchedulerTest {
@Test
public void scheduler() throws InterruptedException {
ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(2);
TaskCompleteEvent taskCompleteEvent = new TaskCompleteEvent(scheduledExecutorService);
Runnable task1 = () -> {
int num = new Random().nextInt(100);
if (num < 5) {
taskCompleteEvent.message("task1-"+UUID.randomUUID().toString(), "Num "+num+" was obatined. Breaking all the executions.", true);
}
};
Runnable task2 = () -> {
int num = new Random().nextInt(100);
taskCompleteEvent.message("task2-"+UUID.randomUUID().toString(), num < 50, false);
};
scheduledExecutorService.scheduleAtFixedRate(task1, 0, 1, TimeUnit.SECONDS);
scheduledExecutorService.scheduleAtFixedRate(task2, 0, 1, TimeUnit.SECONDS);
scheduledExecutorService.awaitTermination(60, TimeUnit.SECONDS);
System.out.println("Success: "+taskCompleteEvent.getSuccess());
System.out.println("Errors: "+taskCompleteEvent.getErrors());
System.out.println("Went well?: "+taskCompleteEvent.getErrors().isEmpty());
}
public static class TaskCompleteEvent {
private final ScheduledExecutorService scheduledExecutorService;
private final Map<String, Object> errors = new LinkedHashMap<>();
private final Map<String, Object> success = new LinkedHashMap<>();
public TaskCompleteEvent(ScheduledExecutorService scheduledExecutorService) {
this.scheduledExecutorService = scheduledExecutorService;
}
public synchronized void message(String id, Object response, boolean error) {
if (error) {
errors.put(id, response);
scheduledExecutorService.shutdown();
} else {
success.put(id, response);
}
}
public synchronized Map<String, Object> getErrors() {
return errors;
}
public synchronized Map<String, Object> getSuccess() {
return success;
}
}
}
You just need to add an additional task whose job it is to monitor all of the other running tasks -- and when any of the monitored tasks fail, they need to set a semaphore (flag) that the assassin can inspect.
ScheduledExecutorService executor = (ScheduledExecutorService) Executors.newScheduledThreadPool(2);
// INSTANTIATE THE REMOTE-FILE-MONITOR:
RemoteFileMonitor monitor = new RemoteFileMonitor(remotesource, localtarget);
// THIS TimerTask PERIODICALLY TRIGGERS THE RemoteFileMonitor:
TimerTask remote = new TimerTask() {
// RUN FORREST... RUN !
public void run() {
try {
kae.trace("TimerTask::run() --> Calling RemoteFileMonitor.check()");
monitor.check();
} catch (Exception ex) {
// NULL TRAP: ALLOWS US TO CONTINUE AND RETRY:
}
}
};
// THIS TimerTask PERIODICALLY TRIES TO KILL THE REMOTE-FILE-MONITOR:
TimerTask assassin = new TimerTask() {
// WHERE DO BAD FOLKS GO WHEN THEY DIE ?
private final LocalDateTime death = LocalDateTime.now().plus(ConfigurationOptions.getPollingCycleTime(), ChronoUnit.MINUTES);
// RUN FORREST... RUN !
public void run() {
// IS THERE LIFE AFTER DEATH ???
if (LocalDateTime.now().isAfter(death)) {
// THEY GO TO A LAKE OF FIRE AND FRY:
kae.error(ReturnCode.MONITOR_POLLING_CYCLE_EXCEEDED);
}
}
};
// SCHEDULE THE PERIODIC EXECUTION OF THE RemoteFileMonitor: (remote --> run() monitor --> check())
executor.scheduleAtFixedRate(remote, delay, interval, TimeUnit.MINUTES);
// SCHEDULE PERIODIC ASSASSINATION ATTEMPTS AGAINST THE RemoteFileMonitor: (assassin --> run() --> after death --> die())
executor.scheduleAtFixedRate(assassin, delay, 60L, TimeUnit.SECONDS);
// LOOP UNTIL THE MONITOR COMPLETES:
do {
try {
// I THINK I NEED A NAP:
Thread.sleep(interval * 10);
} catch (InterruptedException e) {
// FAIL && THEN cleanexit();
kae.error(ReturnCode.MONITORING_ERROR, "Monitoring of the XXXXXX-Ingestion site was interrupted");
}
// NOTE: THE MONITOR IS SET TO 'FINISHED' WHEN THE DONE-File IS DELIVERED AND RETRIEVED:
} while (monitor.isNotFinished());
// SHUTDOWN THE MONITOR TASK:
executor.shutdown();