FIFO vs Standard Queues for Failed Jobs: Why Idempotent Consumers Matter

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The article recommends using a standard queue for most failed-job retries, paired with an idempotent consumer. FIFO queues are only worthwhile when suppressing duplicates within a short five-minute window addresses a real operational risk. The author describes a production case where a webhook delivery timed out after the provider had accepted it, causing a retry that re-sent the same event. The core safeguard is storing each delivery ID so that repeat attempts are recorded as no-ops, ideally using a unique constraint. The piece also outlines a test plan covering timeouts, crashes, and delayed dead-letter redrives to confirm no duplicate side effects occur.

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LiDAR Sensors Face Power-Line Noise That Can Degrade Perception Performance

The article explains that LiDAR units combine precision analog sensing, high-speed digital processing, laser pulse generation, and timing circuits in one compact housing, making them sensitive to electromagnetic interference. Power-supply noise can alter receiver thresholds, timing references, and clock stability, so electrical faults may appear as perception errors. The author argues the LiDAR power input should be treated as an EMC interface, since switching ripple, transients, and ground shifts from robot components like motor inverters and relays can reach the sensor. Conducted noise travels through both differential and common-mode paths, and pulsed laser current draw can also feed noise back into the robot's power network. Because source impedance and cable routing strongly influence these effects, filtering and layout decisions must be based on measured disturbances across the installed power path.

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ProgrammingDEV Community ·

100BASE-T1 Ethernet EMI: Keeping Differential Symmetry to Limit Common-Mode Noise

100BASE-T1 is a single-pair Ethernet technology delivering 100 Mbit/s over one balanced twisted pair, suited to robots, vehicles, and distributed sensor systems where cable weight and packaging matter. Because transmit and receive share the same conductors, impedance discontinuities, imbalances, parasitic capacitance, and layout errors can degrade both signal integrity and EMC. The article stresses preserving electrical symmetry along the whole path from PHY pins through PCB traces, coupling networks, connectors, and cable to the remote node, since asymmetry converts differential energy into common-mode current that radiates and increases susceptibility. It recommends controlled differential impedance, continuous reference planes, matched component values, and careful placement of common-mode chokes near the media interface, with connector and shield termination also affecting overall EMC performance.

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ProgrammingDEV Community ·

AiTM phishing hijacks login sessions to enable business email fraud

A small logistics firm employee received a convincing email with a link to what appeared to be a legitimate cloud login page. After entering credentials and completing multi-factor authentication, the login seemed normal, but an attacker-in-the-middle relayed the process and captured the session cookie. The attacker then accessed the mailbox, created hidden inbox rules, and sent a fraudulent invoice with a changed bank account, which was stopped only by a phone verification. Microsoft reported in 2022 that such AiTM campaigns had targeted over 10,000 organizations since September 2021, and Japan's Anti-Phishing Council recorded about 2.45 million phishing reports in 2025.

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ProgrammingDEV Community ·

Motor Driver EMI: How PWM Switching Creates Electromagnetic Noise

Pulse-width modulation is widely used in motor drives because it efficiently controls voltage, current, torque, and speed. However, the fast switching transitions that give PWM its high efficiency also generate a broad electromagnetic noise spectrum. As a result, a motor inverter acts as a repetitive high-frequency excitation source that couples energy through power cables, motor windings, and chassis structures. The spectrum's envelope depends strongly on rise and fall times, as well as on the switching devices, duty cycle, and modulation scheme. Differential-mode noise arises from rapidly changing currents in power loops, while common-mode noise couples through parasitic capacitance to the chassis and surrounding structures.

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