How do you start parallel instances of 1 durable function via HTTP Post?

Using a Durable Functions template I've created a function that simply starts execution of a method by calling the generated SendEventPostUri request which starts a timer of 60 minutes and completes after the expiration of those minutes.

http://localhost:7228/runtime/webhooks/durabletask/instances/{instanceId}/raiseEvent/{eventName}?code={code}

This works but now I want to send 2 more requests so there are a total of 3 requests running the same method simultaneously at staggered start times and then get the status of each of the requests for the same orchestrator in a JSON response collection but cannot figure out how to do it.

I tried posting the same URI a couple of times but the console output doesn't suggest that there are any more than 1 instance of the method "InitiateDurableFunction" being called or running.

Instead I get a new instance of the Orchestrator, which isn't what I wanted to do.

I can see the status of each new Orchestrator instance using

http://localhost:7228/runtime/webhooks/durabletask/instances/{orchestratorId}?code={code}

How can I start the same method within 1 Orchestrator multiple times or is my expectation not possible?

Also, if this question is a duped post. I cannot find it.

Solution

Each orchestration instance in Azure Durable Functions is isolated , meaning you can't run multiple parallel executions of the same method within a single instance. Instead, you need to start multiple orchestrator instances, each handling its own execution. Use the HTTP Start Endpoint .Instead of raiseEvent, use the startNew endpoint to create new orchestrator instances:

POST http://localhost:7228/api/orchestrators/InitiateDurableFunction?code={functionKey}

Call this endpoint three times (with staggered delays if needed), and each call will create a new instance.

Each response will return a unique instanceId. Store these IDs so you can later query their statuses individually:

GET http://localhost:7228/runtime/webhooks/durabletask/instances/{instanceId}?code={functionKey}

If you want a JSON collection of all statuses, you can write a simple HTTP-triggered function that takes a list of instance IDs and returns their statuses by querying the Durable Task API for each.

Alternative Approach: If you're looking for parallel execution within a single orchestrator, consider using fan-out/fan-in patterns. This allows you to start multiple activity functions in parallel and wait for their completion before aggregating results.