how to avoid concurrent batch jobs running in salesforce

[Prabhakar Chimakurthy]

Description

- 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).

- You may attempt to use the following code sample to avoid encountering this limit, particularly if the batch is executed in a scheduled class.

Resolution

- Count how many current jobs are being executed.
- This information is stored in the AsyncApexJob table.
- Before calling the Database.executebatch() method within a scheduled class, you should try something like:

//check if there are 5 active batch jobs
if ([SELECT count() FROM AsyncApexJob WHERE JobType='BatchApex' AND (Status = 'Processing' OR Status = 'Preparing')] < 5]){
   Database.executeBatch(batchClassInstance);
} else {
   //schedule this same schedulable class again in 30 mins
   nameOfYourSchedulableClass sc = new nameOfYourSchedulableClass();
   Datetime dt = Datetime.now() + (0.024305); // i.e. 30 mins
   String timeForScheduler = dt.format('s m H d M \'?\' yyyy');
   Id schedId = System.Schedule('MatrixRetry'+timeForScheduler,timeForScheduler,sc);
}

- In the same 'else' clause you can send an e-mail to yourselves so you're notified that the job will run a bit later than normal.

Note:

- You can have more than 5 scheduled classes that will call Database.executeBatch() in a Queued status

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Thanks & Regards,
Prabhakar Chimakurthy.

[Ravindra Babu Nagaboina]

Good one, Prabhakar.

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Thanks & Regards.

Ravindra Babu Nagaboina