This article explains how to identify and resolve common causes of Java service slowdown—such as excessive Full GC, high CPU usage, intermittent latency, waiting threads, and deadlocks—by using tools like top, jstat, jstack, and MAT for systematic troubleshooting.
The article explores what a bug really is, why bugs inevitably appear in software development, and offers practical strategies—such as effective logging, leveraging debugging tools, and keeping iteration sizes small—to locate and resolve bugs more quickly.
After a 2018 Flutter upgrade caused a mysterious “Ghost Crash” in Xianyu’s app, engineers traced an over‑released NSMutableArray in the accessibility bridge, fixed an illegal dealloc call, added proper checks for iOS Speak Screen, and eliminated the crash through a rapid gray‑scale rollout.
Spring Boot determines the main application class by creating a RuntimeException, inspecting its stack trace for a method named 'main', and loading the corresponding class via Class.forName, a process illustrated with source code and a JUnit test that compares printed stack traces to the thrown exception.
This article compiles a comprehensive set of Linux commands, JVM utilities, and Java debugging tools—including tail, grep, awk, find, tsar, btrace, greys, JProfiler, jps, jstack, jmap, jstat, and IntelliJ plugins—to help engineers quickly diagnose, monitor, and resolve production issues while optimizing performance.
This article explains how to replace manual print debugging with the lightweight PySnooper decorator, showing step‑by‑step installation, usage, log configuration, and detailed output examples that reveal line execution and variable changes in Python functions.
Learn how to disable robots.txt compliance in Scrapy, use the Scrapy shell for rapid URL debugging, and apply XPath selectors directly in the shell to efficiently extract data, dramatically speeding up development and avoiding repeated full-crawl executions.
An Alibaba Cloud expert walks through a rare Kubernetes node NotReady issue, detailing how PLEG failures, Docker daemon stack traces, runC’s D‑Bus interactions, and a systemd cookie overflow combine to stall nodes, and explains the debugging steps and eventual fix.
This article explains how iOS developers can use Xcode's breakpoint features—including basic toggles, conditional breakpoints, ignore counts, actions like LLDB commands and log messages, exception breakpoints, and symbolic breakpoints—to pause execution, inspect state, and streamline debugging workflows.
This article explains how Xcode’s static analysis feature can automatically identify common iOS development problems—including localization warnings, logical errors, memory leaks, dead stores, and syntax mistakes—by analyzing code without execution, and shows how to resolve each type of issue.
MTHawkeye is Meitu’s iOS debugging and performance‑optimization toolkit that provides a three‑layer architecture—foundation, UI foundation, and plugin layers—to assist developers across development, testing, and production by offering memory leak detection, main‑thread profiling, CPU, network, graphics, storage monitoring, and integrated FLEX utilities.
This article explains how iOS developers can create, configure, and use Xcode breakpoints—including basic, conditional, ignore, action, options, exception, and symbolic breakpoints—to pause execution, inspect state, and streamline debugging with detailed examples and screenshots.
This article explains how Xcode’s static analysis feature can automatically identify text localization problems, logic errors, memory management concerns, dead‑store data issues, and syntax mistakes in iOS projects, and provides step‑by‑step instructions and code examples for fixing each type of warning.
This article analyzes the challenges of reproducing external‑network bugs, outlines common failure causes, and presents a complete design for a JavaScript SDK that records environment data, AJAX calls, errors, and user actions, stores them in IndexedDB, and visualizes the timeline for efficient troubleshooting.
This article explains how to capture Android device logs using adb commands, export them, combine with monkey testing, and then analyze logcat output—including ring buffers, priority levels, and common crash or ANR patterns—to efficiently locate and resolve issues.
This guide compiles a practical toolbox of Linux commands and Java utilities—including tail, grep, awk, find, tsar, jstack, jmap, jstat, btrace, Greys, JProfiler, and RateLimiter—to help engineers quickly locate, analyze, and resolve performance and stability problems in production environments.
This article reveals several lesser‑known Python features—including functions that accept arbitrary arguments, powerful file searching with glob, debugging with inspect, generating unique IDs via uuid, data serialization, string compression, and registering shutdown hooks—providing practical code examples for each.
A detailed post walks through a mysterious 10‑second timeout on fast primary‑key SQLs in a sharding middleware, showing how log analysis, thread blocking, and an inefficient string‑replacement implementation caused the slowdown and how refactoring to StringBuilder restored performance.
This article explores practical Python debugging methods—from simple print statements and structured logging to powerful IDE debuggers, GDB, perf, strace, and the inject debugger pylane—providing code examples, best‑practice guidelines, and tips for improving observability and performance in production systems.
This article explores how understanding human nature and sharpening cognition can dramatically improve developers' technical abilities, offering practical examples ranging from technology selection and debugging to interviews, code reuse, and open‑source strategy.
This guide explains how to set breakpoints, start a debugging session, and use step over, step into, force step into, step out, and drop frame functions in IntelliJ IDEA, along with advanced features like multiple breakpoints, breakpoint properties, and variable value modification.
This guide presents practical Bash scripting techniques—including safety flags, function definitions, variable annotations, modern command substitution, double‑bracket tests, string manipulation, process substitution, built‑in variables, and debugging methods—to help you write robust, maintainable shell scripts.
This article introduces Chrome DevTools console shortcuts—including $0‑$4 for element references, $ and $$ for query selectors, $_ for the last expression result, and $i for importing npm libraries—explaining their usage to streamline front‑end debugging and testing.
The article provides a comprehensive analysis of React Hooks, covering their injection model, persistent call ordering, debugging and testing strategies, API design considerations such as useReducer, Context Provider, useEffect, missing APIs, type handling, compilation optimizations, safety concerns, and the overall motivation behind moving from class components to hooks.
This article describes the motivation, architecture, runtime instrumentation, custom class loaders, and serialization challenges behind Qunar's plug‑and‑play online debugging tool that captures application snapshots without requiring code changes or restarts.
This article introduces JDFlutter, JD's cross-platform mobile development framework built on Flutter, detailing its architecture, integration with existing Android/iOS projects, debugging capabilities, data statistics, exception monitoring, degradation mechanisms, and future outlook as part of JD's dual-engine ARES platform.
A developer ran a series of UPDATE statements that appeared correct, but due to misplaced double‑quotation marks the WHERE clause was parsed incorrectly, causing every row's column to be set to 0; the article explains MySQL's expression evaluation, shows binlog analysis, and offers practical debugging tips.
This article introduces React Native Debugger, explains how to install it on macOS, demonstrates its powerful debugging features for React components, Redux state, and network requests, and provides configuration tips and code examples to help developers efficiently troubleshoot RN applications.
This article introduces Python's PrettyPrinter package, explains why native printing tools fall short, and demonstrates its advanced layout algorithm, syntax‑highlighting, and simple descriptive API for custom pretty‑printing, complete with usage examples and visual screenshots.
This article explores the full range of browser console functions—including formatted logging, object inspection, warnings, tables, assertions, counters, timing, tracing, and grouping—to help JavaScript developers debug more efficiently and gain deeper insight into their code.
This article explains how to use the %c placeholder and CSS strings with console.log to create colorful, formatted debug messages that stand out in large JavaScript log outputs, boosting development efficiency.
JDFlutter is JD.com’s next‑generation cross‑platform framework that integrates Flutter into existing Android/iOS projects, offering a rich UI component library, native API bridges, debugging tools, data statistics, and a roadmap for future multi‑engine development alongside JDReact.
This essay explores the history and inevitability of software bugs—from Grace Hopper’s famous moth to today’s massive codebases—examining developer attitudes, debugging practices, and why writing less code may be the only realistic way to reduce bugs.
This article details a step‑by‑step investigation of frequent full GC events and high CPU usage in a Java backend service, covering memory analysis with SGM, heap dumps, identification of large Base64 image strings, static encryption utilities, and remediation actions such as heap size increase and custom encryption handling.
When a WebSocket‑based service built on Netty started returning massive 5xx errors, we used log analysis, CAT monitoring, reflective access to Netty's internal memory counter, and step‑by‑step debugging to locate and fix an off‑heap memory leak caused by a null subType field in the encoder.
This article compiles essential Linux commands and a suite of Java diagnostic utilities—including tail, grep, awk, find, tsar, btrace, Greys, JProfiler, and others—providing concise examples and code snippets to help engineers troubleshoot and monitor production systems efficiently.
This guide walks through Chrome's console features—including basic output methods, formatted and styled logs, DOM and object inspection, grouped messages, performance profiling, timing, assertions, and useful shortcuts—providing practical examples and tips for effective front‑end debugging.
This article provides a comprehensive overview of frequently used Android Debug Bridge (ADB) commands, explains how to troubleshoot common connection and permission issues, and demonstrates how to manage apps, files, system information, and device operations directly from the command line.
This article explains how to enable and use the React Profiler plugin in React DevTools to record, visualize, and analyze component rendering performance through commits, flamegraphs, sorting charts, component charts, and interactions, and provides troubleshooting tips for common issues.
This guide presents eight practical recommendations for writing robust Bash scripts, covering shebang selection, debugging flags, static analysis with ShellCheck, variable expansion, proper use of local, signal trapping, thoughtful coding habits, and choosing the right tool for the job.
The article teaches Lua developers using OpenResty how to debug with the built‑in debug library and ngx.log, implement object‑oriented patterns via tables and metatables, and perform data operations such as file I/O and cache/database access through lua‑resty‑redis, lua‑resty‑memcached, and lua‑resty‑mysql modules.
This article explains why web push notifications stop working when the browser is closed, how Android and desktop browsers handle push messages, how to open added‑to‑desktop web apps in full‑screen, the evolution from GCM to FCM, and provides detailed troubleshooting steps for authorization, payload encryption, connection issues, HTTP status codes, and error reporting.
Whoops is a visually striking PHP debugging library that simplifies error handling with elegant stack traces and a clean API, making debugging faster and more enjoyable for developers, especially within Laravel and other PHP frameworks.
A production Elasticsearch 5.3.2 cluster showed a persistent 80% heap usage due to a hidden memory leak caused by Log4j thread‑local objects retaining large bulk request data, and the article walks through the investigation, heap‑dump analysis, source‑code tracing, and a practical fix using a JVM flag.
This article provides a comprehensive overview of Python, covering its nature as an interpreted, interactive, object‑oriented language, key benefits, coding conventions, memory management, debugging tools, core concepts like decorators, data structures, namespaces, lambda functions, testing, and many practical programming details for newcomers.
This article explains the concept of deadlocks, outlines the four necessary conditions, and provides a step‑by‑step guide using pstack and gdb on Linux to identify, analyze, and fix thread deadlocks, along with practical prevention techniques.
This guide reveals dozens of lesser‑known Chrome DevTools features—from enabling Canary builds and experimental flags to powerful console shortcuts, DOM selectors, conditional breakpoints, network overrides, and Node debugging—helping developers debug faster and more efficiently.
The Android app’s HLS video produced an electric‑like noise because FFmpeg’s av_find_best_stream mistakenly selected the second audio track in a dual‑stream file, a track lacking 1‑8 kHz frequencies, whereas iOS and PC used the correct first track; fixing requires publishing videos with a single audio track and adding detection tools.
Through detailed debugging and source code analysis, the author discovers that MyBatis's SqlSession.clearCache() does clear the first‑level cache, but the observed stale query results are caused by MySQL's default REPEATABLE‑READ isolation level, which can be resolved by setting the transaction isolation to READ COMMITTED.
This article provides an extensive overview of Android Debug Bridge (ADB), detailing its architecture, core components, and a wide range of commands—including shell am, pm, appops, wm, settings, input, dumpsys, logcat, push/pull, screencap, and screenrecord—illustrated with examples and code snippets for effective mobile testing and automation.
When compiling a Solidity contract in Remix, the “mock compiler: source not found” error occurs because the compiler version isn’t specified, and the guide shows how to set the correct version in Remix settings or directly via the URL, plus tips for spotting low‑level syntax mistakes.
EasyReact is an iOS reactive programming framework that replaces closure‑based data flow with object‑graph nodes, offering visual EZRNode debugging, automatic memory management, and cross‑platform potential while delivering up to 725 % faster performance than ReactiveCocoa, simplifying learning, debugging, and future Swift‑based extensions.
A technical article detailing the investigation and resolution of a MySQL error related to insert buffer merge operations during table deletion, involving code analysis and system debugging.
This article presents a comprehensive guide to writing robust Bash scripts, covering safety options, function definitions, variable annotations, modern syntax like $() and [[ ]], string manipulation techniques, built‑in variables, debugging methods, and recommendations on when to avoid Bash in favor of other languages.
This article provides a step‑by‑step tutorial for creating, configuring, and debugging JDReact projects—including project initialization, npm/yarn setup, styling conventions, routing, network requests, animation handling, scroll‑view tricks, H5 conversion issues, and deployment tips—while highlighting frequent Windows compatibility problems and practical solutions.
An Alibaba tech support engineer investigates a server whose CPU appeared fully utilized, discovers the misleading 'ni' metric, reproduces the issue with high‑nice loops, uncovers hidden mining processes via ld.so.preload, and explains how to detect and mitigate such stealthy CPU hogs.
This guide presents practical Bash scripting techniques—including safety flags, function design, variable annotations, modern command substitution, double‑bracket tests, string manipulation, process substitution, debugging tools, and when to avoid Bash—to help you write more robust and maintainable shell scripts.
Learn how to efficiently debug MySQL source code on macOS using Visual Studio Code and LLDB, covering installation of LLDB via Homebrew, configuring VS Code extensions, setting up local and remote debugging parameters, breakpoint management, and essential command-line steps for seamless development.
This guide presents essential Bash scripting practices—including safety flags, function definitions, variable annotations, modern command substitution, double‑bracket tests, powerful string manipulation, process substitution, here‑documents, debugging techniques, and advice on when to avoid Bash—in a concise, example‑driven format for reliable shell scripts.
The article walks through diagnosing a noticeable UI lag in a PC client’s dial‑pad by capturing ETW traces with Windows Performance Toolkit and UIforETW, revealing that a costly LoadKeyboardLayout call during input‑method switching caused a 0.5‑second delay, and resolves it by filtering the keyboard‑layout state.
This comprehensive guide details the setup, configuration, component customization, routing, context usage, debugging, and deployment processes for building the JD Oil Card Shell application with JDReact, covering both Android and iOS platforms, common pitfalls, and practical code examples.
This article provides a comprehensive step‑by‑step guide for developing the JD oil‑card recharge feature with JDReact, covering project background, environment configuration, branch management, building for Android and iOS, troubleshooting image loading, routing, component customization, network requests, debugging, and release procedures.
This article analyzes a recurring Nginx 502 Bad Gateway error triggered by oversized response headers from PHP‑FPM, explores whether fastcgi_buffer_size is the root cause, captures communication data between Nginx and PHP‑FPM, conducts systematic tests with varying buffer sizes, and draws conclusions about header handling and buffer configuration.
This article analyzes the ten most frequent JavaScript errors identified from over a thousand projects, explains why each occurs, and offers practical code examples and preventive techniques to help developers avoid these common pitfalls.
PrettyPrinter is a Python 3.6+ library that delivers high‑quality, syntax‑highlighted pretty‑printing by improving on existing tools like __repr__, pprint, pprintpp, and IPython.lib.pretty, offering a simple descriptive API for custom formatting and stateful object representation.
Explore the extensive capabilities of the browser Console object—including log, group, table, dir, assert, count, trace, timing, profiling, and custom styling—to enhance debugging and streamline development, with practical examples and visual guides for Chrome.
This article explains how React Native handles network requests differently from web browsers, describes the built‑in fetch, XMLHttpRequest, and WebSocket APIs, outlines debugging methods using proxies, Reactotron, and Chrome DevTools, and discusses strategies for sending binary data such as Base64 encoding and WebSocket support.
This guide walks through a systematic troubleshooting workflow for a Linux gateway that spikes to 891% CPU, using top to locate the offending process, inspecting thread usage, capturing stack traces with gstack, dumping core files, tracing system calls with strace, and analyzing the core dump in gdb to pinpoint the poll() call causing the load.
When Git commands produce hard‑to‑diagnose errors, you can activate detailed tracing in PowerShell by setting the environment variables GIT_TRACE and GIT_CURL_VERBOSE to 1, which makes Git output extensive operation details to help locate the problem.
This article thoroughly explains AJAX cross‑domain issues, covering the underlying same‑origin policy, CORS and JSONP mechanisms, common error manifestations, step‑by‑step backend configurations for PHP, Node.js, Java, .NET, and proxy techniques, plus practical debugging methods using Chrome DevTools.
After deploying a Python server for receiving DICOM medical images, the author encountered severe memory consumption, investigated the leak using tools like gc, objgraph, tracemalloc, and pyrasite, identified a self‑referencing DicomFileLike object with a __del__ method, and resolved the issue by patching the code.
An intermittent MySQL authentication error on Windows caused by the Connector/NET driver’s slow WMI OS‑info query triggers a server‑side timeout, and the article explains how packet analysis revealed the root cause and how caching or removing the WMI call resolves the issue.
This article provides a comprehensive overview of Python fundamentals, covering its interpreted nature, interactivity, object‑oriented features, benefits, coding standards like PEP8, serialization with pickle, memory management, debugging tools, decorators, data structures, namespaces, lambda functions, testing, and more.
The article details a real‑world investigation of a surge of HTTP 406 errors on a Chinese e‑learning platform, tracing the issue to malformed Accept headers sent by a search‑engine crawler and illustrating how CDN routing and header negotiation can cause widespread client‑side failures.
A recent internal Linux mailing list message outlines the key updates in the long‑term support Linux Kernel 4.14, including address‑leak mitigation scripts, default %p hashing, changes to /proc/cpuinfo MHz reporting, and hints about upcoming 4.15 development.
This guide lists the most frequent Python runtime and syntax errors—such as missing colons, misuse of assignment operators, indentation mistakes, type mismatches, and name errors—explains why they occur, and provides corrected code examples to help beginners debug their programs effectively.
Learn how to efficiently locate and fix JavaScript bugs by reproducing errors, setting breakpoints, stepping through code, inspecting variables with Watch expressions, and editing code directly in Chrome DevTools, all demonstrated through a concrete addition calculator example.
This article explains the Android ANR mechanism, common scenarios that trigger it, how the system detects and logs ANR events, and provides step‑by‑step methods for locating and fixing ANR issues, illustrated with a recent WeChat bug example.
This article explains Linux's two‑level memory model, lazy physical allocation, the glibc malloc implementation, chunk metadata, large‑vs‑small allocations, memory holes, debugging hooks, leak detection with mtrace, and practical ways to measure a process's memory usage via /proc.
This article explains how to detect whether inbound or outbound packets are being dropped on a Linux system, shows how to use netstat, dropwatch, and perf to pinpoint the cause, and provides step‑by‑step commands and example outputs for debugging packet loss.
This guide explains why precise bug localization is crucial for testers, outlines systematic approaches with real-world examples, and offers practical tips—including preserving the crime scene, asking the right questions, and interpreting HTTP status codes—to efficiently identify and resolve issues across web applications.
This article shares eight hard‑earned recommendations for writing robust Bash scripts, covering shebang selection, debugging flags, static analysis, variable expansion, proper scoping, signal trapping, defensive coding, and knowing when to switch to a more suitable language.
This guide explores JavaScript's console object, detailing its logging methods, formatting placeholders, table displays, grouping, timing, and additional utilities, while providing code snippets and visual examples to help developers debug and present information effectively in browsers.
This guide walks developers through installing Whistle, configuring one‑click proxy switching, and using its powerful rule‑based features—host mapping, file replacement, request forwarding, script injection, mock responses, remote debugging, and HTTPS support—to streamline frontend network debugging.
A Python developer encountered an ImportError while debugging a script on Ubuntu, traced it to a urllib module conflict, restored the Unity desktop with system commands, and finally resolved the issue by removing a stray urllib.py file that blocked PyCharm's debugger.
This article explains why proper JavaScript error handling is essential, compares syntax and runtime errors, demonstrates good and bad try‑catch patterns, shows how to use global onerror listeners, capture stack traces, and handle asynchronous exceptions to improve frontend code reliability.
This article recounts a baffling C bug where Microsoft's tmpfile() on Windows creates files in C:\, causing a stray backslash to comment out code, and explains how replacing a ternary operator with an if‑else fixed the issue while illustrating common cross‑platform pitfalls.
This article explains why Node.js applications suffer memory leaks, describes V8's memory limits and garbage‑collection behavior, outlines common leak causes, and provides step‑by‑step techniques and tools for monitoring, diagnosing, and resolving leaks in production code.
This article enumerates 35 common bad programming habits—ranging from code organization and team collaboration to testing and maintenance—and explains why they harm productivity, offering concrete advice on how to recognize and replace each habit with healthier practices.
This article shares the most frequent Kotlin-related issues encountered in Android projects—including IDE conversion bugs, DexGuard obfuscation crashes, debugging difficulties, missing ternary operators, and other language quirks—along with practical solutions and code examples to help developers avoid them.
This guide walks through installing XAMPP, configuring MySQL and PHP, setting up Xdebug, and integrating PhpStorm to create a complete PHP development and debugging environment for beginners.
This article surveys the essential JavaScript full‑stack development ecosystem, detailing runtime environments, popular IDEs, build automation tools, testing frameworks, performance utilities, and debugging solutions, guiding developers in selecting the right tools for efficient front‑end and back‑end development.
This article analyzes a frequent Android crash caused by posting delayed Runnables to a Handler, explains why it is hard to reproduce, and presents a solution that extends the delay to reliably trigger and then mitigate the issue using message‑queue manipulation.
This article introduces CTrip's independently built WeChat mini‑program framework, detailing its CPage architecture, middleware, CWX extensions, component APIs, common development problems such as rendering white‑screens, page‑level limits, authorization dialogs, package size constraints, and the solutions and future plans adopted to overcome them.
This tutorial explains how to install and use the devtool utility to monitor, capture heap snapshots, and analyze memory usage in a Node.js application, demonstrating the detection of memory leaks through practical examples and timeline visualizations.
This article lists and explains seventeen typical errors that new Python programmers make—from missing colons and using the wrong operators to indentation problems and misuse of built‑in functions—providing clear examples and corrected code to help readers debug their scripts effectively.
This guide explains why production SQL errors appear despite successful local tests, shows how to proactively log and monitor PHP‑MySQL errors, and provides concrete solutions for frequent MySQL error codes with example code and step‑by‑step troubleshooting tips.
This article debunks the ten most frequent Docker misconceptions—ranging from platform limitations and development workflow constraints to debugging and database usage—by explaining why they are inaccurate and providing practical solutions such as using custom Dockerfiles, volume mounts, remote debugging, and proper container management commands.
This article compiles a comprehensive list of frequently encountered problems and practical solutions for WeChat Mini Program development, covering script environment limitations, navigation constraints, styling rules, network request handling, component usage, platform-specific bugs, and performance tips to help developers build stable mobile applications.
This article explains how to transform Dapper's parameterized SQL into the final executable statement by using a C# helper that replaces @ parameters, eliminating manual substitution and simplifying debugging of large stored procedures.
