Summary This incident examines a subtle but common lifetime‑management failure when using epoll with pointer‑associated event data. The core issue is that the file descriptor and the dynamically allocated object tied to it can fall out of sync, leading to dangling pointers, double frees, or memory leaks if not managed with a disciplined ownership model. … Read more
Summary The NetworkOnMainThreadException occurred when attempting to establish an MQTT connection in an Android Compose app. The issue arose from performing network operations on the main thread, violating Android’s threading rules. Key takeaway: Network operations must be offloaded to background threads or coroutines to prevent UI freezes and crashes. Root Cause Direct network calls on … Read more
Summary A transactional Spring service using JTA (JtaTransactionManager) attempted to commit inside an already-managed global transaction, triggered by an AOP advice that invoked another @Transactional service. The application server correctly blocked this, raising: java.sql.SQLException: IJ031019: You cannot commit during a managed transaction This postmortem explains why this happens, why it is common in legacy Spring … Read more
Summary This incident examines a common misconception in Node.js: “Node.js is non‑blocking, so CPU‑intensive work shouldn’t block anything.” In reality, Node.js is non‑blocking only for I/O, not for CPU-bound JavaScript execution. When heavy computation runs on the main thread, it blocks the event loop, delaying all other tasks. Worker Threads exist to offload that CPU … Read more
Summary Your CNN improved through moderate augmentation but collapsed once augmentation strength exceeded model capacity. The final run shows classic underfitting due to overly destructive transforms, causing the network to latch onto whatever residual patterns remain (runway edges, borders), which explains the “hotter” Grad‑CAM maps. Root Cause The performance drop in Run 5 is driven … Read more
Summary Training LeRobot models with Accelerate+DeepSpeed Stage 3 Offload requires pre-initializing all tensors to avoid runtime errors caused by FP32 data clips that cannot be dynamically created during training. This issue arises when using optimizer offloading to NVMe devices and specific model features like XVLA. Root Cause Dynamic tensor creation: Tensors are typically created on-the-fly … Read more
Summary This postmortem analyzes why a CameraX/Camera2 + PreviewView pipeline on a Pixel 7 shows a narrower field of view (FOV) than the stock Google Camera app, even when using the same lens, aspect ratio, and zoom level. The issue stems from sensor crop regions, stream configuration limits, and PreviewView scaling behavior, all of which … Read more
Summary Xcode 26 throws a “The data being read was corrupted or malformed” error when running iOS projects. This issue is resolved by: Quitting Xcode from the dock Deleting derived data Restarting the connected iPhone Root Cause The error stems from corrupted or missing data in Xcode’s derived data folder, which is essential for project … Read more
Summary Moving from Nginx to Spring Boot for TLS handling required implementing metrics and logging for TLS handshake failures. While overwriting the TrustManager in JSSEUtils.getTrustManagers() allowed capturing handshake data, enriching logs with client IP and hostname proved challenging due to the lack of context within the TrustManager. Root Cause The TrustManager operates at a low … Read more
Summary A custom intermediate URL in front of the Add to Google Wallet save URL is technically feasible, but it introduces a failure mode that often goes unnoticed: the redirect chain breaks the expected contract of the Google Wallet button. This postmortem explains how such designs fail in production, why they fail, and how senior … Read more