[SalesForce] Scheduled Batch Apex Hangs in Queued Status

This is my first crack at a scheduled batch Apex class. Copied the code from the manual but missing something. When I run class MassDeleteSchedules in Anonymous block, it works fine. But when I use the UI to schedule it it just hangs in queued status. I gave it a couple hours and nothing changed so cancelled it. There's only 1 batch that's being scheduled.

I feel like the last 2 lines are causing the issue.

global class JobScheduler implements Schedulable{
global void execute(SchedulableContext scMain){
    CronTrigger ct = [SELECT Id, CronExpression, TimesTriggered, NextFireTime
                      FROM CronTrigger WHERE Id = :scMain.getTriggerId()];

    System.debug(ct.CronExpression);
    System.debug('Number of times batch triggered '+ ct.TimesTriggered);

    //Ensure batch not already triggered
    System.assertEquals(0, ct.TimesTriggered);

    // Sets up query for time period to remove records
    Date dt = Date.today();
    dt = dt.addMonths(-1);
    String dateStr = String.valueOf(dt); // Passing as string for dynamic query below

    String e = 'ONE__Schedule__c';
    String f = 'ONE__Start_Date__c';
    String v = null;
    String q = 'Select id, name from ' + e + ' where ' + f + ' < ' + dateStr;

    MassDeleteRecords del = new MassDeleteRecords(q,e,f,v);       
    Id idbatch = Database.executeBatch(del,2000);
   }
 }

Best Answer

Scheduled Batch Apex jobs appears as Queued status in the Apex Jobs page until the time comes to execute the job (i.e. as per the time you scheduled it to run).

Could it be that you had scheduled it to run by your local clock but the Salesforce time is different and the Job was never actually due to start yet (and hence it will be correctly showing Queued status)?

I see you have put some debug code in the execute() method, did you ever see that in your debug logs? If not, I'd suggest that your Job never even started.

Related Solutions

[SalesForce] Apex Batch job limits not clear Queued vs Scheduled

In practice, Queued counts toward the limit of 5. We have added code to protect against the dreaded 'Attempted to schedule too many concurrent batch jobs in this org' LimitException (since you can't catch LimitExceptions)

Integer enqueuedJobs = [SELECT COUNT() FROM AsyncApexJob WHERE JobType='BatchApex' AND Status IN ('Processing','Preparing','Queued')] ;

if(enqueuedJobs >= 5){
    throw new TooManyBatchApexJobsException();
}

This article is confusing and contradictory too:

http://help.salesforce.com/apex/HTViewSolution?id=000182449&language=en_US

Relevant contradictory statements from that article:

Batch Apex can have 5 concurrent (simultaneous) jobs running in parallel.

That is, explicitly, the number of Batch Apex jobs whose status in the AsyncApexJob table are 'Processing' or 'Preparing'.

A job is not executing when in Queued or any other status.

Scheduling more than 5 Batch Apex jobs returns the error "Attempted to schedule too many concurrent batch jobs in this org"

You may sometimes receive a Developer script exception e-mail when this limit is reached, but not always. (This is also by design).

[SalesForce] Scheduled batch “already scheduled”

I have seen similar behavior before. I've also run into two related issues when running self-scheduling jobs that run a lot:

the "scheduled job" list gets really long even though most jobs in the list have run already
a job in State "DELETED" still holds references to the classes, leading to the dreaded "Schedulable class has jobs pending or in progress" error if/when you try to edit classes in the scope of the job.

The last time I encountered this was a while ago, so API changes may have affected behavior since then, but the approach that has worked with us since is:

the scheduled job is scheduled under a unique name (I use name + System.currentTimeMillis()).
its ID is stored in a custom setting.
when attempting to reschedule, we first call abortJob if the job is returned by [select Id, NextFireTime from CronTrigger where Id = :jobId].
next, we clear all past jobs by deleting the results of [select Id from CronTrigger where State = 'DELETED' and NextFireTime = null].
then we reschedule.

That works for us and has been reliably working for at least a year.

There is another issue you may run into with jobs who run on a one-off (rather than recurring) cron schedule, which is that during major SFDC maint outages/upgrades I've seen what appears to be the symptom of in-progress batch jobs get terminated or not run, leading to a failure to reschedule. To solve that related issue, I'd recommend the approach that Stephen Willcock presented in answer to this question.

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