Two Channels Race — the Queue Overtakes Storage Replication Diagram

Two Channels, One Pair of Systems

The video file is too big for the queue, so the bytes travel through file storage
The web server must explicitly instruct the transcoder, so the instruction travels through the message queue
The instruction references the file, but the two channels replicate independently

The Race

Steps 3-4 travel the queue and overtake the lagging storage replica
The transcoder fetches the original video and gets a stale version or a missing file
It then writes a transcoded copy of the OLD video

Outcome and Lesson

Original and transcoded versions are permanently inconsistent
Two channels between the same pair of systems = race condition unless the storage is linearizable (or the extra channel carries read-your-writes)