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select requires rebuilding and scanning descriptor sets on each wait and has platform-specific descriptor limits; poll also examines a supplied list. epoll maintains kernel-side interest and ready structures, which suits large mostly-idle sets. It does not remove per-connection memory costs, application scheduling, or edge-triggered drain requirements.

PostgreSQL and MySQL support ORDER BY with LIMIT; standard FETCH FIRST syntax is also available in modern versions. Oracle supports FETCH FIRST in current versions; older ROWNUM queries must sort in an inner query before limiting in an outer query. Always specify deterministic ordering and test the exact target version.

On Linux, `ss -lntup` lists listening sockets; `netstat` may be available via net-tools on older systems. Confirm the process, address, and network namespace. A service bound only to 127.0.0.1 is not externally reachable; also check container port mapping and host policy.

String values are immutable and can be safely shared. StringBuilder supports mutable append operations without synchronization and is usually appropriate for thread-confined construction. StringBuffer synchronizes individual methods, but that does not automatically make a multi-call workflow atomic; synchronization often costs more than needed when a builder is local to one thread.

When you pipe commands together, the shell normally reports the exit status of the last command. That hides failures earlier in the chain. Setting pipefail makes the pipeline fail if any stage fails, which is critical for build automation and production scripts where silent partial failures create huge operational risk.

Treat the failure as evidence of an uncontrolled input. Record test order, random seed, runtime, timing, and environment; run the test alone and repeatedly. If it only fails in a suite, inspect shared fixtures, globals, ports, environment patches, clocks, and unawaited tasks before adding retries.

Kafka commits represent when the consumer believes work has been finished. If the offset is committed before the business effect is truly durable, a crash can lose data. If it is committed only after a delay, the application may re-process messages when the consumer restarts. The correct strategy is to commit only after the state change is stored successfully and the work is idempotent enough to recover from retries.