I want a task to be executed after a delay of 3 seconds and my one task takes 2 seconds to finish.
The output i am getting is showing interval of 5 seconds
Note:The Student class implements Callable interface
I have the following queries
Why there is delay of 5 seconds coming.How can make a delay of 3
seconds Why are thread 1 is showed in second execution ,it should be
thread two
The output i am getting is
The time is : Sat Nov 26 15:08:02 IST 2016
Doing a task during : prerna - Time - Sat Nov 26 15:08:06 IST 2016
pool-1-thread-1 Helloprerna
Doing a task during : abc - Time - Sat Nov 26 15:08:11 IST 2016
pool-1-thread-1 Helloabc
Doing a task during : def - Time - Sat Nov 26 15:08:16 IST 2016
pool-1-thread-2 Hellodef
Doing a task during : xyz - Time - Sat Nov 26 15:08:21 IST 2016
pool-1-thread-1 Helloxyz
Doing a task during : ritu - Time - Sat Nov 26 15:08:26 IST 2016
pool-1-thread-3 Helloritu
Doing a task during : babita - Time - Sat Nov 26 15:08:31 IST 2016
pool-1-thread-2 Hellobabita
The code:
private String display(String name2) {
try {
// System.out.println(Thread.currentThread().getName());
name2=Thread.currentThread().getName()+" Hello"+ name;
System.out.println("Doing a task during : " + name + " - Time - " + new Date());
Thread.sleep(000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return name2;
}
#Override
public String call() throws Exception {
// TODO Auto-generated method stub
if (name == "archana") {
throw new Exception();
}
/*} catch (Exception e) {
// TODO Auto-generated catch block
// e.printStackTrace();
}finally{
return "error";
}*/
return display(name);
}
public class ExecutorScheduleDemo {
public static void main(String args[]) throws InterruptedException{
ScheduledExecutorService executor= Executors.newScheduledThreadPool(5);
ArrayList<Student> list = new ArrayList<Student>();
list.add(new Student("prerna"));
list.add(new Student("abc"));
//list.add(new Student("archana"));
list.add(new Student("def"));
list.add(new Student("xyz"));
list.add(new Student("ritu"));
list.add(new Student("babita"));
System.out.println("The time is : " + new Date());
List<Future<String>> resultList= new ArrayList<Future<String>>();
for(Student s:list){
Future<String> f=executor.schedule(s, 3, TimeUnit.SECONDS);
try {
System.out.println(f.get());
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
Use scheduleAtFixedRate(Runnable, long initialDelay, long period, TimeUnit timeunit) instead of schedule(Runnable task, long delay, TimeUnit timeunit).
scheduleAtFixedRate (Runnable, long initialDelay, long period,
TimeUnit timeunit)
Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor. If any execution of this task takes longer than its period, then subsequent executions may start late, but will not concurrently execute.
next execution.
To complete eeedev's answer, since your object seems to be a Callable:
You can simply create a new FutureTask by passing your Callable to the constructor, as described in the oracle docs
Note that the FutureTask's type parameter must be the same as the Callable's.
Example:
class Main {
public static void main(String[] args) {
Foo foo = new Foo();
FutureTask<String> fooFutureTask = new FutureTask<>(foo);
}
}
class Foo implements Callable<String> {
#Override
public String call() throws Exception {
return "Calling";
}
}
You can then schedule your newly created FutureTask for execution as described by eeedev.
Related
Using java concurrent executor, future cancel method not stopping the current task.
I have followed this solution of timeout and stop processing of current task. But it doesn't stop the processing.
I am trying this with cron job. Every 30 seconds my cron job gets executed and I am putting 10 seconds timeout. Debug comes in future cancel method, but it is not stopping current task.
Thank you.
#Scheduled(cron = "*/30 * * * * *")
public boolean cronTest()
{
System.out.println("Inside cron - start ");
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date));
System.out.println("Inside cron - end ");
ExecutorService executor = Executors.newCachedThreadPool();
Callable<Object> task = new Callable<Object>() {
public Object call() {
int i=1;
while(i<100)
{
System.out.println("i: "+ i++);
try {
TimeUnit.SECONDS.sleep(1);
}
catch(Exception e)
{
}
}
return null;
}
};
Future<Object> future = executor.submit(task);
try {
Object result = future.get(10, TimeUnit.SECONDS);
} catch (Exception e)
} finally {
future.cancel(true);
return true;
}
}
The expected result is cron job runs every 30 seconds and after 10 seconds it should time out and wait for approximately 20 seconds for a cron job to start again. And should not continue the older loop because we have timeout on 10 seconds.
Current result is:
Inside cron - start
2019/07/25 11:09:00
Inside cron - end
i: 1
i: 2
i: 3
i: 4 ... upto i: 31
Inside cron - start
2019/07/25 11:09:30
Inside cron - end
i: 1
i: 32
i: 2
i: 3
i: 33
...
Expected result is:
Inside cron - start
2019/07/25 11:09:00
Inside cron - end
i: 1
i: 2
i: 3
i: 4 ... upto i: 10
Inside cron - start
2019/07/25 11:09:30
Inside cron - end
i: 1
i: 2
i: 3 ... upto i:10
The first problem is in this part of code:
catch(Exception e)
{
}
When you invoke future.cancel(true); your thread is being interrupted with Thread.interrupt()
Which means that when a thread is sleeping, it gets awoken and throws InterruptedException which is caught by the catch block and ignored. To fix this problem you have to handle this exception:
catch(InterruptedException e) {
break; //breaking from the loop
}
catch(Exception e)
{
}
The second problem: Thread.interrupt() may be invoked while the thread is not sleeping. In this case InterruptedException is not thrown. Instead, the interrupted flag of the thread is raised. What you have to do is to check for this flag from time to time, and if it's raised, handle interruption. The basic code for it would look like:
try {
if (Thread.currentThread().isInterrupted()) {
break;
}
TimeUnit.SECONDS.sleep(1);
}
...
// rest of the code
UPDATE:
Here's the full code of Callable:
Callable<Object> task = new Callable<Object>() {
public Object call() {
int i=1;
while(i<100)
{
System.out.println("i: "+ i++);
try {
if (Thread.currentThread().isInterrupted()) {
break; //breaking from the while loop
}
TimeUnit.SECONDS.sleep(1);
} catch(InterruptedException e) {
break; //breaking from the while loop
} catch(Exception e)
{
}
}
return null;
}
};
I have 2 schedulers, which executes at a fixedDelay of 5s.
I have 2 use-cases:
If If - condition BusinessLogic class is true, then I want to sleep both the schedulers for a time of 3 secs, which means both the schedulers should execute now after 8 secs [5 secs + 3 secs].
If code qualifies the else condition, then both the schedulers should continue to execute at fixed delay of 5 secs.
Code:
Scheduler class:
import java.util.Date;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
#Component
public class TestSchedulers {
#Autowired
private BusinessLogic businessLogic;
#Scheduled(fixedDelay = 5000)
public void scheduler1(){
Date currentDate = new Date();
System.out.println("Started Sceduler 1 at " + currentDate);
String schedulerName = "Scheduler one";
businessLogic.logic(schedulerName);
}
#Scheduled(fixedDelay = 5000)
public void scheduler2(){
Date currentDate= new Date();
System.out.println("Started Sceduler 2 at " + currentDate);
String schedulerName = "Scheduler two";
businessLogic.logic(schedulerName);
}
}
Business logic class:
import java.util.Random;
import org.springframework.stereotype.Service;
#Service
public class BusinessLogic {
public void logic(String schedulerName) {
if(randomGen() < 100){
System.out.println("\nExecuting If condition for [" + schedulerName + "]");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else if(randomGen() > 100){
System.out.println("\nExecuting Else condition for [" + schedulerName + "]");
}
}
//Generate random numbers
public int randomGen(){
Random rand = new Random();
int randomNum = rand.nextInt((120 - 90) + 1) + 90;
return randomNum;
}
}
The problem
Both the schedulers are not starting at the same time.
When the if part is executing, then only one schedulers sleep for extra 3 secs, but I want both theschedulers to do so.
Log for reference:
Started Sceduler 1 at Sun May 26 12:34:53 IST 2019
Executing If condition for [Scheduler one]
2019-05-26 12:34:53.266 INFO 9028 --- [ main] project.project.App : Started App in 1.605 seconds (JVM running for 2.356)
Started Sceduler 2 at Sun May 26 12:34:56 IST 2019
Executing If condition for [Scheduler two]
Started Sceduler 1 at Sun May 26 12:35:01 IST 2019
Executing Else condition for [Scheduler one]
Started Sceduler 2 at Sun May 26 12:35:04 IST 2019
Executing Else condition for [Scheduler two]
Started Sceduler 1 at Sun May 26 12:35:06 IST 2019
Executing If condition for [Scheduler one]
Started Sceduler 2 at Sun May 26 12:35:09 IST 2019
Executing Else condition for [Scheduler two]
Started Sceduler 1 at Sun May 26 12:35:14 IST 2019
Executing If condition for [Scheduler one]
Started Sceduler 2 at Sun May 26 12:35:17 IST 2019
Executing If condition for [Scheduler two]
Started Sceduler 1 at Sun May 26 12:35:22 IST 2019
Executing Else condition for [Scheduler one]
Started Sceduler 2 at Sun May 26 12:35:25 IST 2019
Executing Else condition for [Scheduler two]
Started Sceduler 1 at Sun May 26 12:35:27 IST 2019
please help..
In each scheduler you invoke if(randomGen() < 100) independently of each other. So for one scheduler it could give result > 100 and for other < 100 or for both it could be the same. What you will need to do is to run randomGen() outside of the schedulers and store the single result in a way that both schedulers can access it and then they will rely on the same value in their if(randomGenValue < 100) statement and will behave the same way
public class QuartzStudy implements Job {
#Override
public void execute(JobExecutionContext jobExecutionContext) {
System.out.println(jobExecutionContext.getJobDetail().getKey().getName() + "-" + Thread.currentThread().getName() + "-" + Thread.currentThread().getId() + "-" + new Date());
}
private static SchedulerFactory schedulerFactory = new StdSchedulerFactory();
private static Scheduler scheduler;
static {
try {
scheduler = schedulerFactory.getScheduler();
scheduler.start();
} catch (SchedulerException e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws SchedulerException, InterruptedException {
JobDetail jobDetail = JobBuilder.newJob(QuartzStudy.class).withIdentity("job1").build();
CronTrigger trigger = TriggerBuilder.newTrigger()
.withSchedule(CronScheduleBuilder.cronSchedule("*/5 * * * * ?").withMisfireHandlingInstructionIgnoreMisfires())
.build();
scheduler.scheduleJob(jobDetail, trigger);
Thread.sleep(10000);
scheduler.pauseJob(jobDetail.getKey());
}
}
This code should console twice and then pause?
But sometimes console three times,why?
job1-DefaultQuartzScheduler_Worker-1-14-Thu Jan 03 09:34:45 CST 2019
job1-DefaultQuartzScheduler_Worker-2-15-Thu Jan 03 09:34:50 CST 2019
job1-DefaultQuartzScheduler_Worker-3-16-Thu Jan 03 09:34:55 CST 2019
First of all, */5 * * * * ? means Every 5 seconds starting at :00 second after the minute.
You are doing Thread.sleep(10000);. This means main thread will be paused for 10 seconds. But, since you are getting logs even in those 10 seconds, that means scheduler is independent of main thread. So, at 10th second, scheduler will create a thread to run execute and also after 10th second, you are pausing job.If first one(i.e. creating of thread occurs before pausing) occurs first, logs will be printed thrice. Whereas if second one(pausing of job occurs before spawning new thread) occurs first, logs will be printed only twice. That's why sometime log is getting printed twice and sometimes thrice.
So, to be sure that logs are printed only twice, decrease sleep time to 9 seconds. I tried below code and it always prints logs twice:
public static void main(String[] args) throws SchedulerException, InterruptedException {
System.out.println("Main method:" + Thread.currentThread().getName() + "-" + Thread.currentThread().getId());
JobDetail jobDetail = JobBuilder.newJob(QuartzStudy.class).withIdentity("job1").build();
CronTrigger trigger = TriggerBuilder.newTrigger()
.withSchedule(CronScheduleBuilder.cronSchedule("*/5 * * * * ?").withMisfireHandlingInstructionIgnoreMisfires())
.build();
scheduler.scheduleJob(jobDetail, trigger);
scheduler.start(); // it's better to start job once you have scheduled one
Thread.sleep(9000);
scheduler.pauseJob(jobDetail.getKey());
System.out.println("Job is Paused!!!");
}
I have Java web application with REST calls using SPRING.
I want to control the number of threads the application is opening for the requests.
So I added Thread config:
package myPackage;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.task.TaskExecutor;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
#Configuration
public class ThreadConfig {
#Bean
public TaskExecutor threadPoolTaskExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(1);
executor.setMaxPoolSize(1);
executor.initialize();
return executor;
}
}
I'm using Sync service not Async, I tested it and it doesn't limit the threads handling the requests, it handles them all at the same time.
What I was expecting is when I send 2 requests at a time - either the 2nd request will be thrown or it will wait until the 1st request will finish.
I'm not implementing Thread in my application at all.
This is the relevant code from my controller:
#RestController
public class Module1Controller {
#RequestMapping(method = RequestMethod.GET, path = "/module1")
InterruptedException {
public Module1 Module1() throws InterruptedException {
Date startDate = new Date();
System.out.println("Thread #: " + Thread.currentThread().getId() + " Request received at: " + startDate);
Thread.sleep(10000);
Date endDate = new Date();
long diff = endDate.getTime() - startDate.getTime();
long seconds = TimeUnit.MILLISECONDS.toSeconds(diff);
System.out.println("Thread #: " + Thread.currentThread().getId() + " thread released at: " + endDate + ", total seconds: " + seconds);
return new Module1(new Clock());
}
This is the console result:
Thread #: 34 Request received at: Sun Dec 17 10:16:20 IST 2017
Thread #: 35 Request received at: Sun Dec 17 10:16:21 IST 2017
Thread #: 34 thread released at: Sun Dec 17 10:16:30 IST 2017, total seconds: 10
Thread #: 35 thread released at: Sun Dec 17 10:16:31 IST 2017, total seconds: 10
What am I missing here?
The problem is that the creation of a TaskExecutor in a configuration bean has no effect on your RestController.
The easiest way to make your RestController process only 1 request at a time is to make the handling method synchronized, e.g. like this:
#RequestMapping(method = RequestMethod.GET, path = "/module1")
public synchronized Module1 getModule1() throws InterruptedException {
If you want a certain maximum number of requests to be processed simultaneously you can use a FixedThreadPool, e.g. like this:
// allow only 2 requests at a time, more requests are automatically placed in a queue
private final ExecutorService es = Executors.newFixedThreadPool(2);
#RequestMapping(method = RequestMethod.GET, path = "/module1")
public Module1 getModule1() throws ExecutionException, InterruptedException {
Future<Module1> result = es.submit(new Callable<Module1>() {
#Override
public String call() throws Exception {
try {
//.... do your work here....
return Module1()
} catch (InterruptedException e) {
return null;
}
}
});
return result.get();
}
I'm not sure why you would want to do this. Limiting the number of requests will result in bad performance and users are not going to like this.
You can not control the threads of request in application instead in container. Maybe you want to run some tasks in limited threads in application. You can do like this:
#RestController
public class ThreadController {
#Autowired
private TaskExecutor taskExecutor;
#RequestMapping(method = RequestMethod.GET, path = "/thread")
public void Module1() {
taskExecutor.execute(new Runnable() {
#Override
public void run() {
Date startDate = new Date();
System.out.println("Thread #: " + Thread.currentThread().getId() +
" Request received at: " + startDate);
try {
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
Date endDate = new Date();
long diff = endDate.getTime() - startDate.getTime();
long seconds = TimeUnit.MILLISECONDS.toSeconds(diff);
System.out.println("Thread #: " + Thread.currentThread().getId() +
" thread released at: " + endDate + ", total seconds: " + seconds);
}
});
}
}
The result:
Thread #: 55 Request received at: Sun Dec 17 22:40:57 CST 2017
Thread #: 55 thread released at: Sun Dec 17 22:41:07 CST 2017, total seconds: 10
Thread #: 55 Request received at: Sun Dec 17 22:41:16 CST 2017
Thread #: 55 thread released at: Sun Dec 17 22:41:26 CST 2017, total seconds: 10
Thread #: 55 Request received at: Sun Dec 17 22:41:32 CST 2017
Thread #: 55 thread released at: Sun Dec 17 22:41:42 CST 2017, total seconds: 10
I'm getting some really weird behavior with multithreading. I have two classes: DipoleTester and Dipole.
DipoleTester attempts to create several Dipole objects, and then run them asynchronously. The problem is that DipoleTester just runs all of its Dipole objects at once, rather than 2 at a time.
Here is DipoleTester:
public class DipoleTester {
public static String DIR = "./save/";
public static void main(String[] args) throws InterruptedException {
Dipole trial;
ExecutorService service = Executors.newFixedThreadPool(2);
for (int r = 10; r < 13; r += 1) {
double radius = (double) r / 10000.0;
for (int matType = 0; matType < 3; matType++) {
String name = "Simple_mat"+matType + "_rad" + radius;
trial = new DipoleSimple(DIR + "Simple/", name);
trial.materialType = matType;
trial.RADIUS = radius;
service.submit(trial);
}
}
service.shutdown();
service.awaitTermination(100, TimeUnit.HOURS);
}
}
And here are the (relevant bits) from Dipole
public abstract class Dipole implements Runnable{
...
public void run() {
initiate();
}
public void initiate() {
DateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date) + ": Starting: " + NAME);
model = ModelUtil.create(NAME);
model.modelNode().create("mod1");
makeParams();
makeVariables();
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
...
}
The problem now is that all the threads execute at once, even with the thread.sleep(5000)! I have no idea what's going on. Here is the console output:
05/08/2013 19:17:31: Starting: Simple_mat0_rad0.001
05/08/2013 19:17:31: Starting: Simple_mat1_rad0.001
05/08/2013 19:17:31: Starting: Simple_mat2_rad0.001
05/08/2013 19:17:31: Starting: Simple_mat0_rad0.0011
05/08/2013 19:17:31: Starting: Simple_mat1_rad0.0011
05/08/2013 19:17:31: Starting: Simple_mat2_rad0.0011
05/08/2013 19:17:31: Starting: Simple_mat0_rad0.0012
05/08/2013 19:17:31: Starting: Simple_mat1_rad0.0012
05/08/2013 19:17:31: Starting: Simple_mat2_rad0.0012
Your Runnable task is throwing an exception before it gets to the Thread.sleep() call. This allows the next task to begin execution. All the tasks fail in such quick succession that all appear to run concurrently.
Make the call to Thread.sleep() the first thing you do in your run() method and you will see that only two threads run at a time.
To detect such failures, you'll need to examine the Future instance that results from each call to submit(). There are other methods for submitting a list of tasks in bulk, and waiting for them to complete, that might be better suited to your application.