Top 3 Polling Interview Questions
Browse 3 real-world technical and behavioral interview questions about Polling. Review scenarios, edge cases, and architectural best practices.
Write a helper that polls a condition until it is true or a timeout expires, then tell me what yours does when the condition throws.
A correct wait helper tracks a wall-clock deadline rather than an attempt count, treats an exception from the condition as a not-yet rather than a failure, returns the condition's value, and reports the last observed value or error when it gives up.
You need a second system reading the same PLC data that SCADA already polls. What could that do to the line?
Answering a poll is work the controller does with the processor that runs its logic, so a second master competes with the control function rather than sitting beside it. Take the feed from the existing aggregation point, and treat the tag map as somebody else's change-controlled artefact.
One of your endpoints takes four minutes to complete. How should the API expose it?
Accept the request, return 202 with the location of an operation resource, and do the work behind a queue. Clients poll that resource or receive a signed callback, and either way the operation id is the contract - one that a callback can reach before the submitter has finished recording it.