Performance Issues

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

Summary This incident examines a common analytical gap in Apache IoTDB: the inability to compute a rate of change between a data point and an N‑th previous point using built‑in functions. The system supports derivative(), but only for adjacent points. When engineers attempt to compute multi‑step deltas (e.g., 10‑step lag), they discover that IoTDB lacks … Read more

Summary The issue occurs when accessing the /login endpoint in a Spring Boot 4.0.2 application with Thymeleaf, resulting in a 404 error despite a valid @GetMapping(“/login”) mapping in the @Controller. The root cause is Spring Boot’s static resource handling overriding the controller mapping. Root Cause Static resource precedence: Spring Boot serves static resources (e.g., HTML, … Read more

Summary The issue at hand is that the UI is not updating during a long press event in a React Native app built with Expo, specifically when running Detox tests on an iOS simulator. This problem arises because the test environment and the app’s event handling are not properly synchronized, leading to a delay in … Read more

Summary Shrinking a SQL Server database, especially one of significant size (700GB), can be a time-consuming process. The provided script attempts to shrink the database incrementally but suffers from inefficiency, taking approximately 2 hours to reduce just 700MB. The root cause lies in the frequent execution of DBCC SHRINKFILE and the lack of optimization for … Read more

Summary Swift 6 strict concurrency requires careful handling of callback-based C APIs, especially when integrating with private frameworks like MultitouchSupport. The challenge arises from uncontrolled thread execution in callbacks, leading to potential data races and concurrency violations. This postmortem explores the root cause, real-world impact, and solutions for bridging such APIs with Swift’s structured concurrency. … Read more