execute apex batch only if not running

Question

I have below trigger where I am executing a batch apex. I need to see whether the batch job is currently not running. Can someone help me here?

Apex trigger:

trigger BatchTrigger on Compliance_Incident_abv__c (after update)
{
 if(Trigger.isUpdate)
 {
  for(Compliance_Incident_abv__c s:Trigger.New)
  {
     ComplianceIncidents_expireNotify st = new ComplianceIncidents_expireNotify();
     database.executeBatch(st);
  }
 }
}

Please let me know if batch code is also needed.

Thanks!

Answer 1

I haven't done this personally but here are some thoughts.

As you may already know, there's AsyncApexJob that holds instance's background jobs (finished or otherwise).

So I think, you can do a simple SOQL when your batch apex starts, i.e.:

public Database.QueryLocator start(Database.BatchableContext bc) {
    Id thisClassId = '<id_of_you_batch_apex_class>'; //can be in a custom label for easier maintenance.
    Id thisJobId = bc.getJobId();
    AsyncApexJob[] jobs = [select id from AsyncApexJob where id!=:thisJobId AND status='Processing' AND ApexClassId=:thisClassId AND JobType='BatchApex'];
    if (jobs==null || jobs.size()==0) {
        return null;
    }
    else {
         //return records to process here
    }
}

These are all based on the documentation of AsyncApexJob object.

Basically, the SOQL is trying to get existing batch jobs (JobType='BatchApex') that is currently in processing status (status='Processing') using the current batch apex class (ApexClassId=:thisClassId) and is NOT the currently running job (id!=:thisJobId).

Again, I haven't tried this personally, but this could be it.

Good luck :)

Answer 2

Normally, I look at Monitoring- >Jobs-> Apex Jobs to check weather a batch is running or not. You can use search menu for it.