Summary Issue: Slow removal of PDF content objects at specific (x, y) coordinates using iText7 due to expensive geometry calculations and initialization. Impact: High latency on complex pages with many operations. Goal: Find a faster, more direct mechanism to identify and remove objects at given coordinates. Root Cause Treating every q … Q block as … Read more
Summary Tcpdump with -i any captures packets from all interfaces, including those not directly visible on the host, such as ipvlan-based pod interfaces. This behavior occurs because the kernel forwards packets to the any interface, even if the interface is not listed via ip addr or ip link. Root Cause The root cause lies in … Read more
Summary A migration from Spring Security 5 → 7 caused the login form submission to return HTTP 404. The root issue is that Spring Security 7 no longer uses WebSecurityConfigurerAdapter, and the old .loginProcessingUrl() and .antMatchers() configuration no longer registers the login endpoint. As a result, the POST to the login URL is not mapped, … Read more
Summary The problem of persisting tooltips in Vega-Lite charts without hover action is a common challenge. The goal is to display and persist multiple tooltips on the chart at the same time, allowing for screenshotting. The expected solution involves finding a workaround to persist multiple tooltips simultaneously. Root Cause The root cause of this issue … Read more
Summary This postmortem analyzes a wkhtmltopdf layout defect where repeated table headers overlap the first row on subsequent pages when rows contain long, multi‑line text. Although the HTML renders correctly in browsers, wkhtmltopdf’s patched Qt layout engine fails to recalculate row heights before placing repeated headers, causing truncation and overlap. Root Cause The failure stems … Read more
Summary This incident examines why a seemingly simple request—plotting a weighted average of two ETF percent‑change series in TradingView Supercharts—fails when implemented naively. Although the user expected Pine Script to directly combine percent‑scaled overlays, the underlying data model of TradingView makes this non‑trivial. The postmortem breaks down what went wrong, why it happens, and how … Read more
Summary This incident analyzes why rm -rf on PolarDB-FileSystem (FUSE mode) is dramatically slower than the same operation on ext4, despite running on the same NVMe SSD. The core issue stems from metadata-heavy operations crossing the user–kernel boundary, compounded by FUSE design constraints and PolarDB-FileSystem’s metadata architecture. Root Cause The slowdown is caused by a … Read more
Summary Choosing the right back-end for a React web app can be daunting, especially for beginners. Key factors include ease of learning, integration with AI/ML, and scalability. For a B.Tech CSE (AIML) student proficient in Python, Flask or FastAPI are ideal choices due to their simplicity, Python-based ecosystem, and compatibility with AI/ML libraries. Root Cause … Read more
Summary The expo-location API failed to retrieve location data on physical Android devices, despite functioning correctly on iOS devices and Android emulators. The issue stemmed from inconsistent permission handling and background service limitations on Android. Root Cause Permission Granting Discrepancy: Android devices required explicit runtime permissions, which were not consistently granted or handled. Background Service … Read more
Summary The issue involves an AXS15231B LCD (model JC3248W535EN) connected via QSPI on an ESP32-S3 using ESP-IDF v5.5.2. The backlight functions correctly, but the display remains blank despite successful initialization and no error logs. The root cause lies in incorrect QSPI bus configuration and missing panel initialization commands. Root Cause Incorrect QSPI bus configuration: The … Read more