bugs accuring during spring batch scheduling - spring

Question

hey guys i am working on spring batch with scheduling (using cron trigger) it is working but with bugs which are the following:
let's assumme that the cron value launches the batch each 10 seconds, when i launch the first and after, for example 3 seconds I launch another one, spring will not be aware of the gap of the 3 seconds and it will launch them both like i have triggered them in the same time
here is my code
this is the class of the job i'll launch
#Component
public class JobThread implements Runnable {
#Autowired
private JobLauncher jobLauncher;
#Autowired
#Lazy
private Job job;
public JobParameters jobParameters;
private Logger log = Logger.getLogger(JobThread.class);
public synchronized void runBatch() {
jobParameters = new JobParametersBuilder().addLong("LaunchTime", System.currentTimeMillis())
.addString("TenantID", BatchController.getCurrentTenant().get()).toJobParameters();
try {
JobExecution jobExecution = jobLauncher.run(job, jobParameters);
log.info("Job's Status:::" + jobExecution.getStatus());
} catch (JobExecutionAlreadyRunningException | JobRestartException | JobInstanceAlreadyCompleteException
| JobParametersInvalidException e) {
e.printStackTrace();
}
}
#Override
public void run() {
this.runBatch();
}
}
the controller which will invoke the job
#RestController
#RequestMapping("tenant/batch")
public class BatchController {
#Autowired
private ThreadPoolTaskScheduler taskScheduler;
#Autowired
#Qualifier("threadPoolTaskExecutor")
private ThreadPoolTaskExecutor taskExecutor;
#Autowired
private JobThread jobThread;
private static ThreadLocal<String> currentTenant;
#PostMapping("/schedule")
public void setBatch(#RequestBody BatchBean cron) {
currentTenant = new ThreadLocal<String>() {
#Override
protected String initialValue() {
new TenantContext();
return TenantContext.getCurrentTenant();
}
};
//cron = "*/10 * * * * *";
taskScheduler.schedule(taskExecutor.createThread(jobThread), new CronTrigger(cron.getCron()));
}
I hope that i have been clear enough
Thanks in advance

Answer 1

The problem is your code it isn't thread-safe and thus potentially dangerous. Also your ThreadLocal isn't going to work as the job will execute in a different thread, and it won't have access to the ThreadLocal.
Don't recreate your ThreadLocal in your controller. Define it once and leave it like that.
Your JobThread is a singleton which keeps state (the parameters) so only the last one will remain.
Program to interfaces TaskScheduler instead of concrete implementatations
Don't create a thread as your JobThread is Runnable already.
Instead of your JobThread to be a singleton, construct a new one as needed and pass in the required parameters.
Your JobThread should look something like this.
public class JobThread implements Runnable {
private final Logger log = Logger.getLogger(JobThread.class);
private final JobLauncher jobLauncher;
private final Job job;
private final String tenant;
public JobThread(JobLauncher launcher, Job job, String tenant) {
this.jobLauncher=launcher;
this.job=job;
this.tenant=tenant;
}
#Override
public void run() {
JobParameters jobParameters = new JobParametersBuilder()
.addLong("LaunchTime", System.currentTimeMillis())
.addString("TenantID", tenant);
try {
JobExecution jobExecution = jobLauncher.run(job, jobParameters);
log.info("Job's Status:::" + jobExecution.getStatus());
} catch (JobExecutionException e) {
log.error(e.getMessage(), e);
}
}
}
Then in your controller inject the needed JobLauncer and Job. When needed construct a new JobThread and pass in the needed information.
#RestController
#RequestMapping("tenant/batch")
public class BatchController {
#Autowired
private TaskScheduler taskScheduler;
#Autowired
private JobLauncher jobLauncher;
#Autowired
#Lazy
private Job job;
#PostMapping("/schedule")
public void setBatch(#RequestBody BatchBean cron) {
//cron = "*/10 * * * * *";
String tenant = TenantContext.getCurrentTenant();
JobThread task = new JobThread(this.jobLauncher, this.job, tenant);
taskScheduler.schedule(task, new CronTrigger(cron.getCron()));
}
On a final note, the precision of System.currentTimeMillis might differ on your OS/System/Architecture. See the javadoc of said method.