Frontend polling may create overlapping requests

[nathabee]

Anomaly 4 — Frontend polling may create overlapping requests

Title

Dashboard polling should prevent overlapping API requests

Type

bug, frontend, performance, polling

Problem

The dashboard appears to poll /printers and /jobs every few seconds. If the backend is slow, unreachable, or blocked, a new polling tick may start before the previous request has completed.

This can produce request accumulation:

t=0s   GET /printers starts
t=5s   previous still pending, new GET /printers starts
t=10s  another GET /printers starts
...

Over time this can make both frontend and backend behavior worse.

Expected behavior

Polling must be non-overlapping.

For each polling loop:

• do not start a new request if the previous one is still running
• optionally abort old request with AbortController
• count timeout/network failures
• keep only the latest successful state
• avoid updating the DOM from stale responses

Acceptance criteria

• If /printers request is still pending, the next /printers poll is skipped or delayed.
• If /jobs request is still pending, the next /jobs poll is skipped or delayed.
• Slow backend responses do not create a request backlog.
• Stale responses cannot overwrite newer dashboard state.
• Network failures are counted by the offline-state mechanism.

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