A Spring‑based service repeatedly hung because Redis connections were never returned to the pool, leading to thread starvation; the article walks through the investigation using top, jstack, Arthas, and code analysis, then shows the proper way to use RedisCallback and release connections to prevent the deadlock.
After a week of intermittent API hangs in an internal sandbox, we traced the issue to Redis connection pool blocking caused by missing max‑wait configuration, leading to threads waiting indefinitely; by adjusting Jedis pool settings, using proper connection release, and avoiding unsupported commands, the deadlock was resolved.
This article demystifies source maps by explaining their purpose, the mapping mechanism, Base64‑VLQ encoding, and the full range of webpack devtool options, while providing practical code examples, best‑practice configurations for development and production, and detailed tables of keywords and fields.
The article walks through Go’s memory allocator by first demonstrating assembly‑level debugging with Delve, then detailing its TCMalloc‑inspired design where tiny, small, and large objects follow distinct paths through per‑P caches, central spans, and the global heap, highlighting the roles of mcache, mcentral, mspan, and mheap.
The article discusses identifying and resolving ImageIO-related crash issues in iOS applications, particularly those occurring after iOS 14 updates, by analyzing crash logs and system behavior.
This article explores how Java developers can use the ASM framework, the Instrument API, and JVM TI to dynamically generate and transform bytecode at runtime, enabling powerful debugging features like Evaluate and custom agents for class redefinition.
This article introduces the jps tool for listing Java processes, explains its common options and usage examples, then provides a detailed overview of jstack, including its purpose, command syntax, thread‑state definitions, sample outputs, and practical tips for detecting deadlocks, counting threads, and diagnosing high CPU usage in Java applications.
To improve debugging speed and reduce issue resolution time, the article recommends defining a unified LogObject structure with fields such as eventName, traceId, msg, costTime, request, and response, using JSON serialization, and discusses adding traceId, consolidating request/response logs, and implementation examples in Java.
This guide walks through configuring Spring Boot 2.3.10 with OAuth2 client support, detailing required dependencies, application and security settings, common session‑related errors, step‑by‑step debugging of OAuth2LoginAuthenticationFilter and OAuth2AuthorizationRequestRedirectFilter, and the final solution of aligning hostnames to preserve cookies.
This comprehensive guide walks you through IntelliJ IDEA's debugging features, covering the interface, basic shortcuts, variable inspection, expression evaluation, smart step‑into, conditional breakpoints, multithreaded debugging, frame rollback, request interruption, and JRebel activation for hot‑deployment.
A morning outage revealed an ingress‑nginx CrashLoopBackOff caused by a non‑TLS secret, and this article walks through the log analysis, code inspection of the controller startup, the faulty extractTLSSecretName logic, and the two‑pronged fix to prevent future crashes.
Debugging is inevitable for programmers, and this guide presents ten practical strategies—from mindset adjustments and bug reproduction to log analysis, online research, code commenting, breakpoint usage, and even the quirky rubber duck method—to help developers efficiently locate and resolve bugs across any codebase.
This article explains why data exchange between numerous frontend plugins in large‑scale applications is hard to trace, reviews common debugging techniques, adapts backend tracing ideas, and presents a concrete implementation for retrieving and validating plugin data in real time.
This article explains the concept of Flutter hot reload, why it is essential for efficient mobile development, answers common questions, demonstrates Dart‑based hot‑reload demos, shows how to enable VM service, automate reloads, and provides an in‑depth source‑code walkthrough of the Flutter toolchain.
This article explains why well‑structured error logs are essential for troubleshooting, analyzes common sources of errors, and provides concrete guidelines and code examples to make logs complete, specific, and actionable for developers and operations teams.
Cyberbrain, a Python debugging tool created by a Tsinghua alumnus and Google engineer, records detailed data flow, variable changes, and program states, then visualizes them, enabling developers to debug more efficiently without manually stepping through code.
This guide explains how to enable core dumps on Linux, examine the generated core file, and pinpoint the exact source line of a crash using dmesg, addr2line, gdb, and strace, with concrete command examples and code snippets.
This guide introduces the most essential Visual Studio Code extensions for Python developers, covering tools for code analysis, snippets, docstring generation, testing, preview, type hinting, and Jupyter Notebook integration, each with download links and key features to boost productivity.
LLDB is a high‑performance debugger integrated with Xcode that supports C, Objective‑C, and C++ development; this article introduces its command‑line syntax, explains key commands such as help, expression, thread, breakpoint, watchpoint, and image, and provides usage examples to improve debugging efficiency.
This article presents a comprehensive technical overview of the K‑Song recommendation platform, covering its backend architecture, the evolution of recall strategies, feature management and ranking pipelines, large‑scale deduplication techniques, and the debugging and monitoring infrastructure that support high‑performance personalized music recommendations.
This article walks through a real‑world Linux kernel bug investigation, showing how to detect a frozen process, use tools like ps, strace, pstack, and the /proc filesystem to trace system calls, identify the blocking kernel function, and pinpoint the root cause.
This guide explains how to enable core dumps on Linux, examine the generated core file, and pinpoint the exact source line that caused a crash using dmesg, addr2line, gdb, and strace, with step‑by‑step commands and example code.
A developer recounts a five‑day debugging saga where a new lock‑free network queue caused intermittent core dumps, ultimately traced to differing GCC optimization behaviors, and shares practical lessons on bug attitude, reproduction, static analysis, and effective logging.
Effective error logging provides crucial clues for troubleshooting, yet many logs lack context, consistency, or detail, making debugging time‑consuming; this article explains common error sources, fourteen typical causes, improvement measures, and practical guidelines—including formatting rules and code examples—to help developers write clear, actionable logs.
This step‑by‑step guide shows how to locate a Linux process frozen in uninterruptible sleep by using tools such as top, ps, WCHAN, /proc files, strace, pstack, and kernel stack traces to pinpoint the offending system call and its root cause.
When using the laravel-sms extension with Luosimao, SMS sending fails because the package uses an HTTPS endpoint while the official documentation specifies HTTP, and correcting the URL in the LuosimaoAgent.php file resolves the issue.
The article explains why Nginx silently discards request headers containing underscores, demonstrates the issue with a Spring Boot service and Postman, and shows how adding the 'underscores_in_headers on;' directive resolves the problem.
The article explains Android native crashes (NE) by describing .so file composition, the need for un‑stripped libraries, how to view and generate stripped/un‑stripped binaries, and detailed workflows using ndk‑stack, DropBox, BreakPad, objdump, addr2line, and minidump_stackwalk to reconstruct stack traces and pinpoint source lines.
This article explains why using plain print() for debugging can become confusing in larger Python projects and demonstrates how the Icecream library provides concise, informative output with minimal code, including installation, basic usage, custom prefixes, context information, and clean‑up techniques.
This guide lists frequent Python errors such as invalid syntax, unexpected EOF, invalid characters, index out of range, type mismatches, indentation issues, value errors, name errors, and attribute errors, providing clear definitions, common causes, and key vocabulary for each.
This guide introduces GoBoy, a multi‑platform Game Boy and Game Boy Color emulator written in Go, explains how to install it on macOS, Windows, and Linux, and details its usage, debugging commands, and saving features for a complete retro gaming experience.
This article analyzes a crash caused by NSInvocation argument out‑of‑bounds on iOS 13.3+, explains the underlying runtime changes, demonstrates how to reproduce the issue with a timer‑triggered message forwarding scenario, and provides a fix by correcting the method signature.
This guide walks you through powerful IntelliJ debugging techniques—including conditional breakpoints, the Drop Frame feature, multithread breakpoint control, remote JVM debugging setup, and on‑the‑fly expression evaluation—to help you troubleshoot complex Java applications efficiently.
This guide explains how to identify OutOfMemoryError crashes in Android applications caused by excessive thread‑pool creation, using tools like Android CPU Profiler, adb ps commands, and code hooks, and provides concrete steps to refactor OkHttp, RxJava, and SDK usage to prevent resource leaks.
JupyterLab now offers a visual debugger plugin and the xeus‑python kernel, allowing users to set breakpoints, inspect variables, and navigate execution directly in notebooks, with simple installation commands and future enhancements such as richer variable rendering and conditional breakpoints.
Faced with a legacy Dubbo service needing both Dubbo and HTTP protocols and a new Spring Cloud project requiring seamless Feign calls, this article details the challenges, the solution using Dubbo’s SPI Container extension, and how Arthas was employed to diagnose and resolve hidden loading errors.
This tutorial explains how to create a VS Code extension that automatically prefixes console.log statements with custom identifiers, covering project scaffolding, key file structures, activation events, command registration, implementation details, debugging, and publishing to the marketplace.
This article introduces a collection of essential Java tools—including jstack, jmap, jhat, jstat, jdb, jcmd, jps, jinfo, javap, javac, jconsole, and jvisualvm—explaining their purposes, common commands, and how they help diagnose memory leaks, CPU spikes, thread issues, and overall JVM performance.
IntelliJ IDEA 2020.3 introduces a revamped welcome screen, reader mode, easier window splitting, enhanced refactoring, upgraded debugging tools, AI‑powered code completion, Search Everywhere improvements, Java 15 support, built‑in database tools, Lombok integration, and a refined VCS menu, all aimed at boosting developer productivity.
This guide explains what strace is, how to use it for filtering system calls, profiling execution time, diagnosing configuration issues, and tracing network activity, providing concrete command examples and interpretation of output to help troubleshoot Linux processes efficiently.
Learn how to enhance Python debugging using the PySnooper library, covering quick installation, simple examples, advanced features like output redirection, variable watching, depth control, thread info, custom representations, and remote debugging tips, all illustrated with clear code snippets and screenshots.
This article explains why effective error logging is crucial for debugging, analyzes common causes of errors across system layers, and provides concrete guidelines and code examples for writing complete, specific, and actionable error logs that simplify issue identification and resolution.
This guide walks through Chrome DevTools features—including inspecting pseudo‑class styles, temporarily toggling classes, making pages editable, checking placeholder styles, testing performance and SEO, viewing network details, examining event handlers, searching code globally, recording runtime performance, using rendering diagnostics, and exploring application storage—providing step‑by‑step instructions with code snippets and visual examples.
This article compiles a curated list of practical VS Code techniques—from refactoring code and customizing view layouts to fast debugging, symbol navigation, terminal management, Git operations, and essential shortcuts—offering developers concrete ways to accelerate their workflow and write cleaner code.
This article describes how the author investigated recurring errors in a Java-based lecture hall system, identified thread pool leaks caused by improper use of AsyncHttpClient, and resolved the issue through command‑line diagnostics, code fixes, and system monitoring, improving stability.
This article explains several IntelliJ IDEA debugging tricks—including setting conditional breakpoints, using Drop Frame to rewind execution, managing multi‑thread breakpoints, configuring remote debugging, and evaluating or modifying expressions on the fly—to help developers debug complex Java applications more efficiently.
This article explains the fundamentals of Linux ftrace, details the event‑tracing mechanism and tracepoint macros, shows how to enable and filter events on ARM64 Android devices, and demonstrates a practical workflow for capturing low‑probability scheduling bugs in camera‑related processes.
This guide explains how to configure Android Studio and LLDB to perform native debugging of the Dalvik virtual machine on Android devices, covering both scenarios with and without app source code, required environment setup, useful LLDB commands, and step‑by‑step procedures for remote debugging.
After migrating from Docker to Docker Swarm and finally to Kubernetes, the author shares six practical kubectl troubleshooting techniques—including inspecting deployments, viewing events, streaming logs, exporting YAML, scaling pods, and port‑forwarding—to quickly identify and fix common cluster issues.
This article provides a comprehensive overview of Google’s V8 JavaScript engine, covering its architecture, compilation process, bytecode, hidden classes, inline caches, garbage collection, and debugging tools such as d8, with practical code examples and performance optimization tips for developers.
A web testing engineer recounts how a user‑reported gray banner on a Chrome browser led to a step‑by‑step investigation that ultimately uncovered the AdGuard extension as the culprit, illustrating practical troubleshooting techniques for front‑end issues in production.
This article walks through the ThinkPHP framework's initialization process, explains the underlying design patterns, shows how to trace method calls with debug_backtrace, and discusses configuration loading, container updates, debugging mode, and code redundancy, providing practical code examples for developers.
This article demonstrates how to locate and extract cover‑image URLs from a web page using Scrapy, explains handling absolute and relative URLs, shows the necessary XPath and meta‑passing code, and provides debugging tips to verify that the image URL is correctly transferred through the spider.
This article provides a detailed walkthrough of ThinkPHP's initialization process, explains how to trace method executions using debug_backtrace, analyzes the init method and container configuration updates, and offers practical suggestions for code optimization and debugging in backend development.
This article explains how to investigate a MySQL crash when core dumps are disabled by extracting the crash address from the error log, obtaining the matching binary, using GDB to map the address to source code, and decoding encoded function signatures to pinpoint the underlying bug.
This article explains what remote debugging is, why it is useful, introduces the JPDA architecture, details the JDWP command‑line options such as transport, server, suspend, address, and shows step‑by‑step how to start a Spring Boot service in remote‑debug mode and attach IntelliJ IDEA for debugging.
When starting a Spring Boot application, WARN messages about missing JAR files appear because Tomcat incorrectly scans Manifest Class-Path entries, and the article explains the root cause, debugging steps, and multiple ways to resolve the issue.
The article investigates a CPU load spike caused by a red‑black tree cycle inside Java's HashMap after JDK 8, detailing monitoring steps, stack‑trace analysis, heap dump inspection, and concluding with a recommendation to replace HashMap with ConcurrentHashMap in concurrent scenarios.
After noticing abnormal memory usage in a production service, the author traced a leak to a race condition in shared data during a C++ code refactor, demonstrated the debugging steps, explained why traditional tools like Valgrind help, and shared lessons on avoiding multithreaded memory leaks.
This guide shows how to quickly reformat code without opening settings, generate UML class diagrams, view and test Spring Boot endpoint mappings, navigate debugging execution points, and rename methods using IntelliJ IDEA Ultimate shortcuts, enhancing productivity for Java developers.
This article details a two‑month journey of reading MySQL 8.0.20 source code to uncover how the DELETE statement performs mark‑delete, describing the experimental setup, trace‑log analysis, query and delete phases, and the exact functions that set the deletion flag in InnoDB.
The article explains a puzzling bug where a Groovy‑created object's toString becomes empty after fastjson serialization, traces the issue to Java access modifiers, demonstrates the problem with sample code and console output, and resolves it by adding a public modifier.
This article explains why C heap memory leaks cause board resets after months of operation, describes heap allocation methods, the three key leak elements, common release misconceptions, and provides practical code‑review techniques to detect and eliminate leaks.
The article shares the author's personal experience of reading source code—starting with Java collections, moving to Spring and MyBatis, diving deep into Spring Boot and Quartz integration, and offering practical tips such as using official guides, books, blogs, design‑pattern knowledge, and IDE breakpoint debugging to master backend frameworks.
This article explains why iOS launch images often fail to update, reveals that the system caches multiple storyboard‑generated images in the app sandbox, and provides a step‑by‑step method to replace those cached files with custom‑generated ones, including code, orientation handling, and support for older iOS versions.
This guide walks you through Linux process fundamentals and equips you with practical commands—ps, strace, pstack, pstree, gdb, and /proc file inspection—to diagnose, trace, and debug running programs step by step.
This article examines the complexities of testing environments, outlines typical causes of failures such as resource constraints, external dependencies, and service bugs, and provides systematic troubleshooting methods, useful tools, and real‑world case studies to improve reliability and efficiency.
This article explains how Node.js child_process.spawn handles stdio options, why failing to attach 'data' listeners or consume pipe streams can cause the child to block, and demonstrates experiments, debugging techniques, and proper configuration such as using 'ignore' or 'pipe' to avoid deadlocks.
This article demonstrates how the open‑source Java diagnostic tool Arthas can be employed in various production scenarios—such as CPU spikes, class‑loading conflicts, method‑level monitoring, performance bottlenecks, and hot‑code replacement—to rapidly locate and resolve runtime problems without restarting services.
This guide details typical Laravel 7 installation problems—such as missing PHP extensions, version mismatches, 403 errors, cache and permission issues—and provides step‑by‑step Composer commands, code snippets, and troubleshooting solutions to help developers quickly resolve them.
This article explains why Python programs raise common built‑in exceptions, illustrates each with clear code examples, and shows practical techniques for catching, raising, and debugging these errors to write more robust code.
After an AWS network jitter caused lingering slow Redis requests in a Java project using Redisson sentinel, the team traced the issue through source code inspection, custom Prometheus metrics, chaos‑blade testing, and Arthas debugging, ultimately identifying a connection‑pool bug and submitting a fix to Redisson's master branch.
Explore essential IntelliJ IDEA techniques—including string highlighting with regex validation, batch replacement via Alt+J, interactive Java Streams debugging, enhanced auto‑completion for Stream APIs, and document block rendering—to boost your Java development productivity and streamline code editing workflows.
This article explains how to set up the environment, identify key MyBatis components such as SqlSession, Executor, StatementHandler, ParameterHandler, TypeHandler, and ResultSetHandler, and strategically place breakpoints to effectively read and understand MyBatis 3.5 source code within a Spring Boot 2.3.3 application.
Discover ten practical VS Code techniques—from fast refactoring and custom view layouts to debugging, symbol navigation, split editing, terminal renaming, Git shortcuts, search snapshots, and visual page building—that can dramatically improve your frontend development efficiency and productivity.
A production MySQL server was overwhelmed by a high‑volume query that ignored a crucial composite index because the leftmost key was missing, leading to full‑table scans, CPU saturation, and a half‑hour outage, and the post explains how the issue was diagnosed and fixed.
This article explains MySQL 8.0.20's lexical analysis, describing the lexer’s role, the state‑machine implementation, step‑by‑step debugging with LLDB on macOS, the init_state_maps function, key source code snippets, and the optimizations introduced in this version.
This comprehensive guide explains how to use IntelliJ IDEA's Debug mode—including launching the debugger, managing breakpoints, inspecting variables, evaluating expressions, employing smart step‑into, configuring conditional breakpoints, handling multithreaded debugging, and using drop‑frame and force‑return features—to efficiently trace and troubleshoot Java applications.
This article critically examines Fiddler Everywhere, comparing its free and Pro editions, highlighting missing capabilities, analyzing the product roadmap and update cadence, and concluding why the tool is unlikely to become popular despite its attractive pricing.
This article explains Java's Compare-And-Swap (CAS) mechanism, illustrates its usage with AtomicInteger code examples, walks through step‑by‑step debugging of CAS operations, and discusses its advantages, limitations such as the ABA problem and spin‑wait overhead.
An intermittent slowdown in a Java SaaS app, even during low traffic, was traced to a Log4j locking bug that blocked hundreds of threads; capturing a thread dump, analyzing it with fastthread.io, and upgrading to Log4j2 resolved the issue.
This tutorial shows Python developers how to configure the interpreter so that a short "peace mantra" is automatically printed before any script or interactive session runs, using usercustomize.py, PYTHONSTARTUP, and simple shell setup to help keep bugs at bay.
This article introduces ten practical IntelliJ IDEA plugins for Java developers, explaining their core features, shortcuts, and visual cues, so you can streamline code generation, dependency management, JSON conversion, decompilation, and more while avoiding common pitfalls.
This article explains the root cause of a memory‑leak bug in JDK8's ConcurrentLinkedQueue, demonstrates how to reproduce and visualize the issue with custom CLQ implementations, analyzes the removal algorithm, and shares practical debugging tips including a notorious IDEA debug pitfall and its resolution.
The article explains why effective error logging is crucial for troubleshooting, analyzes common sources of errors, and provides concrete guidelines and code examples for writing clear, complete, and actionable log messages that aid developers in quickly identifying and resolving issues.
This comprehensive tutorial walks you through installing PyCharm Community or Professional, creating and configuring Python projects, writing and running code, debugging, unit testing, version control integration, using plugins, and leveraging advanced features such as remote development and profiling, all illustrated with screenshots for macOS, Windows, and Linux.
This article explains how Android native exceptions (NE) are captured, processed, and logged as tombstone files, detailing the signal registration, debuggerd workflow, crash_dump execution, unwinder backtrace generation, and how developers can analyze the resulting data using tools like addr2line.
A Java Spring service method misused map.contains and REQUIRES_NEW transaction propagation, leading to unreleased DB connections and a CannotCreateTransactionException, and the article walks through the bug, its root causes, and concrete fixes including correct key checks and timeout settings.
jcmd, introduced in JDK 7, is a powerful built‑in Java diagnostic tool that lets you send commands to running JVMs, replace utilities like jstack and jmap, and perform tasks such as listing processes, printing thread stacks, retrieving heap information, and using Java Flight Recorder.
The article explains how to integrate Flutter into existing iOS projects using both source code and product (binary) approaches, detailing scripts, Podfile modifications, and build processes to enable seamless debugging and minimal native impact.
This article provides a comprehensive guide to using Arthas for Java backend debugging, covering installation, core trace and watch commands, OGNL expression syntax, practical examples for inspecting method calls, accessing static fields, and integrating with Spring context via advanced command techniques.
The article recounts the author's evolution from avoiding source code to actively reading JDK, Spring, MyBatis, Shiro and Quartz implementations, explains why reading code matters for interviews and personal growth, and shares practical methods—including official docs, books, blogs, and IDE breakpoint debugging with concrete Spring Boot‑Quartz examples.
The article details a step‑by‑step investigation of a Spring Boot application that unexpectedly used 7 GB of physical memory despite a 4 GB heap limit, revealing how native memory allocations, the Inflater class, and glibc memory pools caused off‑heap leaks and how proper configuration and library updates resolved the issue.
This article walks through a real‑world Dubbo debugging case where a NoClassDefFoundError was silently swallowed, showing how to use Arthas watch commands to capture the exception, analyze the root cause in static initializers, and fix the logging dependency conflict.
This article explains Python error handling using try...except...finally, demonstrates how to interpret tracebacks, and introduces debugging techniques such as print statements, assertions, and the pdb module, providing code examples and practical guidance for developers.
The article outlines a six‑step method for diagnosing sporadic JVM hangs in a high‑concurrency Xianyu service—starting with code review, live state capture, I/O checks, lock analysis, resource‑exhaustion assessment, and finally framework thread‑pool tuning—to uncover lost‑lock behavior and severe thread‑pool imbalance that cause prolonged lock waits despite low CPU load.
This guide explains the Linux packet‑receive path, shows how to verify UDP loss with tools like ethtool, ifconfig, and netstat, and provides step‑by‑step methods to identify NIC, driver, kernel, firewall, buffer‑size, and application causes while offering concrete commands to adjust ring buffers, sysctl parameters, and socket settings.
This article narrates a detailed, step‑by‑step debugging process for a sudden drop in data volume caused by Kafka partition bottlenecks, covering problem verification, code inspection, environment checks, logging, packet capture, load testing, and the final resolution of increasing partition size.
This article introduces essential JDK command‑line tools such as jps, jinfo, jstat, jmap, jhat and jstack, explaining their options, usage examples, and how they help developers monitor, diagnose and troubleshoot Java applications in production environments.
The article recounts a detailed troubleshooting process—including data verification, code review, DBA assistance, local debugging, environment comparison, logging, packet capture, service restarts, async‑to‑sync changes, load testing, and Kafka partition tuning—that ultimately identified a Kafka partition bottleneck as the cause of a sudden data‑volume decline after a new feature went live.
