Azure WebJobs - Singleton WebJob on user basis

I need to run, on a scheduled period, a job for different users (e.g. CRM synchronization). This synchronization is triggered by a message on a ServiceBus queue put by another function that is triggered by a TimerTrigger every 30 minutes.

Now what I'd need is to avoid that each user job is run multiple times in parallel, i.e. I would need to block the processing of the same job for the same user if the previous job is not completed.

Let's visualize like this:

• at 09:00 in the morning, the TimerTrigger function is executed. This function determines that user A and user B must be synchronized. For each of these users, a message on a ServiceBus queue is put.
• a different Azure WebJob is triggered as soon as a message is put onto the ServiceBus queue. Jobs are generated and execution is running.
• at 09:10 user A synchronization job completes, while user B's is still running. Let's suppose that it is still running even at 09:30.
• at 09:30, the TimeTrigger function is executed again. This function determines again that user A and B must be synchronized. The message on the queue is put again.
• Function is triggered again twice because of the two messages, but there are currently two concurrent functions running for user B.

How to avoid this?

Do I have to implement manually a logic for Azure Lease Blobs?

Thanks.

Use WebJob's [Singleton] attribute. That acts like a distributed lock. Underneath, it's implemented with blob leases. This is a method-level attribute. You can provide a "scope" which determines the granularity of the lock; and the scope can be based on binding data.

See https://github.com/Azure/azure-webjobs-sdk/wiki/Singleton for more details.