Too Many Devices Error

Question

https://github.com/Azure/azure-iot-sdk-java/blob/main/iothub/device/iot-device-samples/file-upload-sample/src/main/java/samples/com/microsoft/azure/sdk/iot/FileUploadSimpleSample.java

Hello,

I am trying to use the above example. I can upload one file to my Azure Blob container fine. Then I start a loop to upload 400+ files. After about 24 files, I get the error "Failed to get the file upload SAS URI" , cause "TooManyDevicesException". I cannot find any documentation explaining why this error comes up.

I cannot seem to get rid of the error and have to wait till the next day and the code runs fine again until the 24th or so upload.

I am closing the client. I am send the "completefileuploadnotification" etc. I am testing the exact same code just to see if this code works vs my code. It seems the example code also has the same issue.

I tried reading the documentation but there is no clear explanation saying if you do this then you will get this particular error.

Any insights. solutions or Wiki I can read where the cause of this error is explained?

Thanks for any help provided. I will follow up on each lead and post what worked to resolve it.

Jerry

Answer 1

Hi @Jerry Naidoo I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to accept the answer .

Error Message:

Failed to get the file upload SAS URI" , cause "TooManyDevicesException"

Issue:

Trying to upload 400+ plus files using the file upload sample results in TooManyDevicesException and fails to upload files.

Solution:

Changing the structure of the file upload code helped resolve the issue.

Here is the initial code structure.

//pseudo code
Start upload loop
	new client
	open client
	uploadfile
	close client
loop end

Here is what worked to address the issue

//pseudo code
new client
open client
	Start upload loop
	uploadfiles
	loop end
close client

If I missed anything please let me know and I'd be happy to add it to my answer, or feel free to comment below with any additional information.

I hope this helps!

If you have any other questions, please let me know. Thank you again for your time and patience throughout this issue.

Kindly note that, even though the issue is resolved with the changed code structure, the limitations mentioned by Sander above are still valid. If you try to use the same code concurrently and upload files onto a different device in your IoT Hub, you will still get throttled with respect to the limitations.

Answer 2

Hello @Jerry Naidoo ,

welcome to this moderated Azure community forum.

There are some limitations to the IoT Hub file upload feature:

1.67 file upload initiations/sec/unit (100/min/unit) for the S1

and

10 concurrent file uploads per device

Can you check if you reach any of these limitations in your test?

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If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.

Answer 3

Hello,

I continued to debug and finally I found my issue.

My code was structured as like this:

//pseudo code
Start upload loop
	new client
	open client
	uploadfile
	close client
loop end

I then changed it to this structure and I no longer get the toomanydevicesexception

//pseudo code
new client
open client
	Start upload loop
	uploadfiles
	loop end
close client

I followed my structure basing my experiences on USB/SERIAL ports. We never keep the connection open longer than needed but I guess for this type of operation it needs a one time open and one time close.

Hope this helps someone one day.

Regards

Jerry