Suthahar Jegatheesan MSDEVBUILD / blog Multi-Stack Dev Build · by Suthahar
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The upload froze the app for 8 seconds.

The fix is the cheapest queue Azure sells, and a pointer instead of a payload.

What you'll learn

  • Why image processing inside the request exhausts the web tier
  • The claim check: put a blob path on the queue, not the file
  • How visibility timeout and DequeueCount handle a dead worker
Azure 10 steps 32 seconds —views

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Understand it one step at a time

The short runs these in order in about 32 seconds. Here they are written out — pick any step to jump the short straight to it.

1 Step 1 of 10

Upload. Then nothing happens

A 4.2 MB photo uploads and the screen just hangs. No progress bar, no response — because the API hasn’t returned yet.

Frequently asked questions

Why move image processing out of the upload request?
Processing the image inline holds a web-tier thread and the user's connection open for the whole operation — do that under load and you exhaust the web tier's capacity. The upload request should end as soon as the answer the user needs — upload succeeded — is known.
What is the "claim check" pattern used here?
Upload the image to blob storage, then put only a small message (the blob's path, here 182 bytes) on the queue — not the file itself. A background worker picks up the message and does the processing, and visibility timeout plus DequeueCount handle a worker that dies mid-job.

Free app · no app store

These are built for a phone

Every short is drawn at full portrait height, the shape a phone already is. Installed, it opens full-bleed with no address bar across the top — and the whole library reads offline.

How it works

Read deeper on Azure

Twenty seconds gets the shape of an idea across. These go into how it behaves in production.

More shorts

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