Weird Runtime Error: The action did not produce a val...

[keilorblend360]

I have two Runtime actions:

1) Get a list (array) of files to download (filename -> download URL)

2) Upload file contents to database. 

The array in action 1 contains 200-250 key/value pairs at any given time. Per key/value pair in the Action 1 array, I invoke action 2 (upload files) as non-blocking via the OpenWhisk package. I'm also leveraging a 5 second delay after every 10 results to avoid concurrency error.

for (let i = 0; i < filesToUpload.length; i++) {		
  if((i + 1) % 10 === 0 )await sleep(5000);
  var name = 'upload-file';
  var blocking = false;
  var result = true;
  var params = {file: filesToUpload[i]};
		
  await ow.actions.invoke({name, blocking, result, params}).then(result => {
    activations.push(result);
  }).catch(err => {
    activations.push(err);
  })
}

When I look at my activation log (limit 50) after running action 1 (consequently invoking 200-250 action 2), I see 85% success, but 15% have a "developer error" status:

When I dig into an individual activation with a "developer error" using wsk activation get, I see this in the response:

"response": {
        "status": "action developer error",
        "statusCode": 0,
        "success": false,
        "result": {
            "error": "The action did not produce a valid response and exited unexpectedly."
        }
    }

I have no idea why this is happening without any real rhyme or reason. The error message is non-descriptive and doesn't really help me drill down to the root of the issue. I have proper error handling set up and return error statusCodes/messages when errors happen in my code. 

@Mihai_Corlan , you seem to be the Runtime responder in this forum from Adobe. Any thoughts on this?

[Mihai_Corlan]

Hello,

Two things come to my mind:

1. Do you have logs in action 2? do you have some try catch that return an error object?
2. I suspect that action 2 is set to run concurrently in the same container. Tweak the concurrency value to 100 and see if this happens again https://github.com/AdobeDocs/adobeio-runtime/blob/master/guides/throughput_tuning.md

Cheers,
Mihai