Polling
Polling is the repeated checking or querying of a resource, system, or condition, often at intervals, to detect data, events, or state changes.
Latency
Polling is the repeated checking of a device or status condition by software instead of waiting for an interrupt.
- How it is used
- Uses polling to reduce unpredictable interrupt interference in latency-sensitive device and network I/O.
- How deep it goes
- Defines active checking, explains idle-work costs and Linux’s hybrid network behavior, but does not provide a polling implementation.
- Examples
- Illustrates polling with a Linux network driver checking a NIC for packets and switching modes when traffic stops.
- What you can do after
- Evaluate/understand polling versus interrupts by weighing controllable latency against unnecessary checks during idle periods.
API Design Patterns
A polling loop is a repeated sequence of requests that checks an asynchronous operation until a completion condition is reached.
- How it is used
- Uses repeated status requests to retrieve results from asynchronous long-running API operations.
- How deep it goes
- Defines the request loop, delay strategies, API methods, costs, and recovery concern without detailing transport internals.
- Examples
- Demonstrates CreateChatRoom, GetOperation, a one-second delay, and a chat-room result.
- What you can do after
- Apply it via GetOperation and an operation ID, then return the completed result after the done condition is reached.
Logs and Telemetry
Polling is a technique in which a client periodically requests data or checks state from a service.
- How it is used
- Collects Prometheus metrics and Kubernetes events through recurring endpoint and API requests.
- How deep it goes
- Explains interval trade-offs, failure modes, security implications, SQLite deduplication, and Kubernetes plugin configuration.
- Examples
- Uses Prometheus scraping of Fluent Bit and a kubernetes_events input polling Kubernetes every five seconds.
- What you can do after
- Operate/configure a Kubernetes event poller while choosing intervals, preventing duplicates, and protecting API credentials.
Python Concurrency with asyncio
Polling is a technique that repeatedly checks a resource to determine whether it is ready for processing.
- How it is used
- Uses polling to check non-blocking sockets or refresh web data when no event-driven alternative is applied.
- How deep it goes
- Explains polling through socket-loop behavior and HTTP tradeoffs, then contrasts it with event notifications and WebSockets.
- Examples
- Uses a non-blocking echo server and a live user counter to demonstrate polling costs and alternatives.
- What you can do after
- Evaluate polling overhead and choose event notifications or WebSockets when repeated checks waste CPU or server resources.
The Art of Code
A communication technique in which a program repeatedly requests an endpoint to check for changes.
- How it is used
- Uses repeated endpoint requests to detect changes in dashboards and similar applications.
- How deep it goes
- Defines polling, illustrates fixed intervals and wasted requests, and stops short of implementation code.
- Examples
- Uses weather or financial dashboards and a five-second-versus-five-minute interval comparison.
- What you can do after
- Evaluate polling intervals and choose between polling and push-based updates for a use case.
Data Pipelines with Apache Airflow, Second Edition
Polling is the technique of repeatedly checking an external system or condition at intervals until a desired state is observed.
- How it is used
- Coordinates Airflow workflows with external data arrival by repeatedly checking conditions before downstream processing.
- How deep it goes
- Defines condition checks, success and timeout behavior, intervals, and overload risk, but not sensor internals.
- Examples
- Uses supermarket delivery timelines, a FileSensor, a CSV path, task logs, and configurable poke intervals.
- What you can do after
- Operate/configure Airflow sensors to wait for files and control checking intervals and timeouts.
Read how Data Pipelines with Apache Airflow, Second Edition explains polling →
Learn Rust in a Month of Lunches
Polling is the process of repeatedly checking asynchronous computations for progress or completion.
- How it is used
- Coordinates asynchronous futures so multiple operations can progress together or race toward the first completion.
- How deep it goes
- Explains sequential awaits, join!, select!, and try_join! with runnable examples, but does not describe executor internals.
- Examples
- Demonstrates random delays, ordered sequential output, variable join completion order, selection, timeout handling, and failed or successful joins.
- What you can do after
- Apply it via Tokio macros to poll futures concurrently, select the first result, add a timeout, or propagate join errors.
Read how Learn Rust in a Month of Lunches explains polling →
Build Your Own Robot: Using Python, CRICKIT, and Raspberry Pi
Polling is a technique that repeatedly checks a resource or condition at a configured interval.
- How it is used
- Uses repeated filesystem checks to detect newly saved camera frames and drive downstream image applications.
- How deep it goes
- Explains a reusable watcher, modification-time comparison, loop timing, and web-stream integration without deeper scheduling internals.
- Examples
- Demonstrates watching robo_stream.jpg and forwarding changed JPEG frames to a browser at a 60-check-per-second interval.
- What you can do after
- Build it from scratch as a Python FileWatcher and apply it to camera-file monitoring or browser video streaming.
Read how Build Your Own Robot: Using Python, CRICKIT, and Raspberry Pi explains polling →
The Design of Web APIs, Second Edition
A polling strategy repeatedly sends requests to check the current state or result of an asynchronously running operation.
- How it is used
- Handles long-running API operations by separating initiation from status retrieval.
- How deep it goes
- Explains the request sequence and optimization metadata, but does not detail client scheduling algorithms.
- Examples
- Uses an on-demand bank stock-market stress test lasting up to an hour.
- What you can do after
- Apply it via HTTP by starting an operation, following its status URL, and adapting request timing.
Read how The Design of Web APIs, Second Edition explains polling →
Related concepts
- WebSocketalternative to · WebSocket is a network protocol that enables persistent, bidirectional, full-duplex communication between endpoints over a single TCP connection.
- sensorused by · An Airflow sensor is a task component that repeatedly waits for an external condition or event and succeeds when it becomes true.
- source connectorused by · A source connector is a Kafka Connect connector that reads data from an external source system and publishes records to Kafka.
- HTTP GETuses · HTTP GET is a request method for retrieving a representation of a resource identified by the request target, without requesting a state change.
- event loopused by · An event loop is a runtime mechanism that repeatedly selects ready events or tasks and dispatches their associated work for execution.
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