The article explains why the Java JVM throws java.lang.OutOfMemoryError: Unable to create new native threads, outlines common causes such as thread leaks, insufficient RAM, other processes, and kernel limits, and provides practical solutions and troubleshooting steps to resolve the issue.
This article analyzes six common MySQL query performance traps—type conversion, function usage, left‑most prefix, implicit charset conversion, left‑most match, and optimizer mis‑selection—illustrates each with real‑world SQL examples, explains why they degrade performance, and provides concrete remediation steps and verification tools.
This guide explains what Prometheus monitoring is, walks through downloading the correct version for a Kubernetes cluster, customizing alert rules, deploying and cleaning up Prometheus, and troubleshooting common Alertmanager connection problems by checking DNS and network configurations.
This guide explains how to install Erlang, download and compile RabbitMQ 3.0.4, start the server in detached mode, verify its status, and troubleshoot common issues such as port conflicts on CentOS 6, providing complete command‑line instructions and configuration tips.
During a New Year holiday, an Oracle database suffered severe hangs due to a GC buffer busy acquire wait event caused by a faulty heartbeat network cable, leading to index unusable errors and extensive troubleshooting steps that reveal common causes and preventive measures.
This article outlines the most important Linux log files under /var/log, explains what each records—from system and kernel messages to authentication, web server, database, and firewall events—and shows practical commands for inspecting them, helping SREs improve fault detection and system observability.
This article walks through a step‑by‑step troubleshooting process for JVM Out‑Of‑Memory (OOM) incidents, covering symptom identification, monitoring tools like top, jstat, and jmap, root‑cause analysis, and actionable recommendations to prevent future memory leaks.
This article explains common Kubernetes DNS resolution failures, both for external domains and internal service discovery addresses, and provides a step‑by‑step troubleshooting workflow that includes checking CoreDNS, examining resolv.conf, adjusting DNS settings, and recreating CoreDNS when necessary.
This guide explains common Kubernetes DNS problems—including failure to resolve external domains, inter‑pod service discovery addresses, and related impacts on applications like Nginx reverse proxies—and provides step‑by‑step troubleshooting procedures such as checking CoreDNS, inspecting resolv.conf, and customizing dnsPolicy and dnsConfig in pod specifications.
This guide compiles 99 practical kubectl commands that cover every aspect of Kubernetes troubleshooting—from cluster and node information to pod health checks, service and deployment diagnostics, networking, storage, RBAC, scaling, and advanced debugging tools—helping operators quickly identify and resolve issues in their clusters.
This article details a step‑by‑step investigation of OceanBase single‑node replica expansion failures, highlighting missing sys‑tenant expansion, deprecated table replica commands, log_disk_size misconfiguration, log‑stream mechanics, and provides concrete SQL and ALTER statements to reproduce and resolve the issue.
This article provides a detailed overview of common Linux server failures, a step‑by‑step methodology for fault isolation, practical monitoring tools and commands, and a real‑world case study illustrating diagnosis and remediation techniques for production environments.
When a Linux server's CPU spikes to 100%, this guide walks you through a systematic investigation—from identifying the high‑load process and pinpointing the offending Java thread to applying a streamlined shell script—so you can resolve the issue and restore normal performance.
A recent data‑center migration caused certain Kubernetes pods to experience significantly higher latency, which was traced to Redis connection‑pool misconfiguration and lock contention in the Gateway service, and resolved through ARMS code‑hotspot analysis and configuration adjustments.
This article details a week‑long investigation of intermittent Nacos service deregistration in a Spring Cloud Alibaba microservice environment, describing the background architecture, multiple hypothesis tests, diagnostic commands, kernel version mismatch, and the final fix by upgrading the Linux kernel.
This article provides a complete, illustrated walkthrough for downloading and installing Anaconda on Windows, configuring the environment, launching Jupyter Notebook, and troubleshooting common issues such as missing environment variables and permission errors.
A Spring Boot application on CentOS 6.x hung while fetching Apollo configuration because a single /etc/hosts entry listed dozens of domain names, causing hostname resolution to fail; splitting the entry into multiple lines restored normal startup and highlighted a kernel‑specific hosts parsing bug.
This guide outlines frequent Jenkins problems—including master startup failures, out‑of‑memory errors, plugin incompatibilities, disk space exhaustion, configuration corruption, and Java compatibility issues—and provides step‑by‑step troubleshooting procedures to keep CI/CD pipelines running smoothly.
This guide explains why a production Redis cluster may show intermittent timeouts and READONLY errors, analyzes root causes such as network jitter, resource saturation, and costly commands, and provides step‑by‑step troubleshooting and configuration fixes to restore stability and performance.
This guide explains how to use tcpdump for network packet capture, covering basic and advanced filtering options, interface selection, host and port targeting, saving captures to files, and a real‑world troubleshooting scenario involving a Node.js server behind Nginx.
This guide explains why a PostgreSQL connection attempt fails with “FATAL: password authentication failed for user ‘postgres’”, outlines common causes such as wrong passwords and misconfigured postgresql.conf or pg_hba.conf, and provides step‑by‑step solutions including password reset, config correction, trust authentication and environment rebuild.
This guide explains how to verify disk alerts, locate large directories and files using df, du, and find commands, handle discrepancies caused by deleted files, and adjust system-reserved space to efficiently free up disk space on Linux servers.
This guide compiles crucial Linux commands for viewing logs, inspecting CPU, memory, disk I/O, network, system load, and performing common administrative tasks such as IP configuration, file system cleanup, and service health checks, helping sysadmins quickly diagnose and resolve issues.
This guide compiles the 20 most common Linux and Kubernetes troubleshooting commands, illustrating typical outputs and step‑by‑step diagnostic reasoning for high CPU load, disk pressure, network failures, pod crashes, node issues, service outages, database errors, and application performance problems.
This tutorial walks you through installing Erlang, downloading the RabbitMQ server, starting it in detached mode, verifying its status, and troubleshooting common TCP‑listener errors on CentOS systems, providing all necessary commands and configuration details.
This guide walks through typical Linux operational problems—including boot failures, network issues, MBR and GRUB errors, forgotten root passwords, and read‑only file‑system symptoms—explaining their causes, step‑by‑step diagnostic methods, and practical recovery commands to restore a healthy system.
This guide explains why a PHP SoapClient call may return an empty result, shows the relevant code, and provides step‑by‑step instructions to enable the SOAP extension in php.ini, followed by links to additional programming learning resources.
This guide explains how to diagnose and fix TiKV disk‑space problems by identifying oversized log files, redundant space‑placeholder files, and excessive RocksDB/Titan data, offering command‑line checks, configuration tweaks such as enabling log rotation, disabling reserve space, and tuning GC and Titan discardable‑ratio to restore balanced storage.
This comprehensive guide walks you through systematic JVM memory issue diagnosis, covering initial data collection, analysis of heap, metaspace, direct memory, stack problems, and practical command‑line tools, while offering actionable tips and real‑world examples for effective troubleshooting.
This guide introduces nine commonly used kubectl commands—get, create, edit, delete, apply, describe, logs, exec, and cp—explaining their purposes, providing practical examples, and offering tips to help system administrators streamline Kubernetes resource management and troubleshooting.
This article details a step‑by‑step investigation of a compaction‑stuck problem in OceanBase, covering background, environment setup, view and log analysis, root‑cause identification related to clock drift, and the corrective actions taken to restore normal merging.
This guide explains why Elasticsearch throws cluster_block_exception, walks through diagnosing disk space, cluster health, node failures, read‑only settings, and index misconfigurations, and provides step‑by‑step commands and preventive measures to keep your cluster stable.
This guide walks you through ten practical nslookup commands for retrieving A, NS, SOA, MX, any, PTR records and more, showing how to adjust timeouts, enable debugging, and query specific DNS servers to troubleshoot and verify domain configurations.
This article explains why disk space may not be freed after deleting large log files on a Linux server, describes the underlying file system mechanisms, and provides a step‑by‑step troubleshooting guide using /tmp cleanup and the lsof command to identify and kill lingering processes.
This article explains what TCP RST packets are, why they appear during connection establishment, data transfer, and termination, and how to analyze their causes—including server refusals, client errors, firewall policies, retransmission limits, idle timeouts, and bypass blocking—using sequence diagrams and practical diagnostics.
This guide explains why MySQL or Java processes can consume 700‑900% CPU in production, walks through step‑by‑step diagnosis using Linux tools, and provides concrete remediation techniques such as indexing, caching, thread analysis, and code adjustments to restore normal performance.
This guide compiles 50 practical troubleshooting and remediation techniques covering system, network, application, database, and security layers, enabling operations engineers to quickly diagnose failures, apply targeted fixes, and maintain stable, secure infrastructure.
This guide walks you through installing Erlang, downloading and extracting RabbitMQ 3.0.4, starting the server in detached mode, verifying its status, and troubleshooting common port‑conflict errors on CentOS 6, with complete command‑line examples.
This article analyzes a Redis cluster outage caused by a slot‑migration bug where a node simultaneously migrated slots in and out, leading to conflicting config epochs, gossip‑protocol mismatches, and MOVED errors, and provides detailed troubleshooting steps and preventive measures.
This article explains why Linux kernel network packet loss occurs, covering causes such as UDP checksum errors, firewall misconfigurations, rp_filter settings, buffer overflows, and hardware faults, and provides detailed diagnostic steps and practical solutions to identify and resolve each issue in Linux environments.
After installing multiple LNMP services, a reboot left the Ubuntu system unable to run apt update due to a read‑only filesystem caused by a missing /etc/fstab, and this guide walks through diagnosing the issue, restoring fstab with correct UUIDs, remounting the root, and backing up the configuration.
When a data platform server suddenly shows CPU utilization near 99% despite modest traffic, this guide walks through pinpointing the offending Java process, tracing the high‑load thread, uncovering a time‑conversion routine that over‑calculates seconds, and applying a lightweight fix that drops CPU load by dozens of times.
This article explains why CoreDNS may experience DNS resolution timeouts in a Kubernetes cluster, how to analyze logs and timeout settings, locate upstream DNS problems, and apply practical solutions such as adjusting timeout values, switching upstream DNS servers, and deploying a local DNS service.
This article presents a detailed walkthrough of a MySQL InnoDB deadlock case, covering background, log inspection, data preparation, reproduction steps, lock analysis, root‑cause explanation, and practical solutions to prevent and resolve similar deadlock issues.
This guide walks through installing Prometheus on a Kubernetes cluster, customizing alert rules, handling service exposure, and diagnosing common Alertmanager connection issues by inspecting CoreDNS and CNI configurations, offering practical solutions for reliable cloud‑native monitoring.
This article presents a practical guide for backend developers to troubleshoot Linux performance problems, covering essential analysis tools, a systematic diagnosis method, and detailed checklists for CPU, memory, disk I/O, and network I/O issues.
This article outlines practical troubleshooting steps for eight frequent production problems—including OOM, CPU spikes, interface timeouts, index failures, deadlocks, disk issues, MQ backlogs, and API errors—providing clear guidance and code snippets to help engineers quickly identify root causes and resolve them.
This article provides a comprehensive, step‑by‑step guide to the most important native Linux networking commands—such as hostname, host, ping, curl, ip, ss, traceroute, dig, and tcpdump—explaining their purpose, common usage examples, and key options for effective system and network troubleshooting.
A detailed post‑mortem of a three‑time service outage reveals how hidden bugs, frequent FullGC, a saturated connection pool, and an unindexed slow SQL query crippled a Spring Boot backend, and shows the step‑by‑step troubleshooting, temporary fixes, and lasting improvements applied.
This guide explains what RabbitMQ is, walks through installing Erlang and RabbitMQ on a Linux system, shows how to start and verify the server, and provides troubleshooting tips for common startup errors such as port conflicts.
The article presents a concise mind‑map of essential Linux performance tools and a flexible troubleshooting workflow, guiding backend developers through CPU, memory, disk, and network issues by using utilities such as top, oprofile, slabtop, iotop, netstat, and strace to quickly pinpoint and resolve bottlenecks.
The article analyzes a MySQL replication error where a MEMORY table is cleared after a master restart, explains why the binlog records only a statement despite row format, and provides step‑by‑step troubleshooting and remediation measures to ensure data consistency.
This guide explains why MySQL blocks a host after many failed connections, outlines common causes such as wrong credentials, network issues, and configuration errors, and provides step‑by‑step solutions including log inspection, credential verification, network checks, application fixes, and commands to unblock the host while also offering preventive measures.
This article walks through a real‑world Redis latency incident, detailing systematic troubleshooting steps, key metrics to monitor, command‑line diagnostics, and practical optimizations such as scaling, pipelining, and hot‑key mitigation to restore service performance.
This guide walks through fixing four common Jenkins pipeline problems: replacing unreachable plugin update sites with domestic mirrors, resolving Maven build errors caused by missing server JVM libraries, clearing stale Git config lock files, and adjusting file descriptor limits on build nodes to prevent out‑of‑resource failures.
This article explains common scenarios that cause MySQL or Java processes to consume 900% CPU, walks through step‑by‑step diagnosis using Linux tools, and provides concrete optimization techniques such as indexing, caching, thread analysis, and code adjustments to bring CPU usage back to normal levels.
This article walks through a real‑world OceanBase OMS migration case where adding an OCP association triggers a “Server Internal Error”, detailing log analysis, metadb schema inspection, OAT deployment checks, the impact of the MySQL “-f” flag, a temporary fix, and the root‑cause conclusion.
GRUB2, the widely used second‑generation bootloader, offers multi‑platform support, modular design, and powerful command‑line tools; this guide explains its architecture, boot stages, configuration file syntax, common settings, and practical examples for dual‑boot, troubleshooting, and custom startup options.
The article walks through diagnosing and fixing a Git clone timeout on Windows by checking SSH connectivity, discovering DNS misresolution, and correcting the local hosts file to map github.com to its proper IP address, enabling successful repository cloning without a proxy.
The article walks through real interview scenarios where MySQL or Java processes consume 900% CPU, detailing step‑by‑step diagnosis with top, processlist, jstack, and concrete remediation such as adding indexes, using caches, fixing busy loops, and tuning memory.
This guide explains why embedded development seems difficult and provides a systematic approach to reproducing, locating, analyzing, and resolving typical embedded problems—including simulation conditions, log printing, online debugging, version rollback, binary search commenting, register snapshots, stack overflow, and hardware quirks—plus regression testing and experience summary.
Linux system performance depends on CPU, memory, disk I/O, network, kernel parameters, and hardware, and troubleshooting requires comprehensive checks using tools like top, vmstat, iostat, netstat, perf, and sysctl, with step‑by‑step guidance for identifying bottlenecks, optimizing resources, and tuning TCP settings.
This article demonstrates how to diagnose and resolve repeated UPDATE failures in OceanBase by extracting information from Top SQL, log files, and the gv$sql_audit view, identifying error codes such as 6005, 6003, and 6212, and applying corrective actions like adjusting timeout settings, killing lock‑holding sessions, and checking lock statistics.
This guide compiles the most frequent Linux and network problems faced by operations engineers—ranging from non‑executing shell scripts and cron output issues to read‑only filesystems, disk space leaks, and service start failures—providing clear causes and step‑by‑step solutions for each case.
An investigation reveals that a cron‑scheduled script repeatedly launches a process because the limited PATH in cron’s environment prevents the pidof command from running, causing the script to misinterpret the process count as zero, and the fix is to set the correct PATH.
The article walks through diagnosing a Java SSLHandshakeException caused by an untrusted HTTPS certificate when fetching a PDF, and presents three solutions: using InstallCert to add the certificate, configuring trustStore properties, and finally bypassing verification with a custom TrustManager and HostnameVerifier.
Linux’s “watchdog: BUG: soft lockup – CPU#1 stuck” warning indicates a CPU soft lockup, caused by driver bugs, hardware faults, or kernel issues, and can be resolved by updating software, monitoring hardware, analyzing logs, and implementing preventive performance and hardware checks.
This article demonstrates how to use the JDK's built-in command-line and graphical tools—such as jps, jinfo, jvisualvm, jstat, jstack, and jcmd—to monitor JVM performance, analyze GC behavior, inspect thread stacks, and troubleshoot memory and configuration issues in Java applications.
This guide walks you through checking CPU usage, system load, resource consumption, problematic processes, system logs, and performance bottlenecks on a Linux server using common command‑line tools such as top, uptime, pidstat, strace, tail, and perf.
After experiencing up to 50% battery loss overnight when the MacBook lid is closed, the author diagnosed the issue using pmset, identified Bluetooth and Handoff as culprits, and applied three configuration changes—including disabling network wake, turning off Handoff, and using Bluesnooze—to reduce nightly drain to under 5%.
When a user reported errors, I discovered a MySQL table flooded with millions of bad rows from a new group, causing slow queries and crashes; I detail the step‑by‑step investigation, failed attempts with DELETE and lock‑free changes, and the final successful rebuild using temporary tables, DROP, TRUNCATE, and index reconstruction.
This article explains common causes of extreme CPU usage in MySQL and Java applications, provides step‑by‑step troubleshooting methods using Linux tools and SQL commands, and presents real‑world case studies with concrete optimizations such as indexing, caching, and thread‑handling adjustments.
This guide walks you through checking CPU utilization, system load, process resource consumption, tracing problematic processes, reviewing logs, and using performance tools to pinpoint and resolve high CPU usage on a Linux server.
This guide explains why the host‑side veth peer of a Docker container’s network interface matters and provides four practical methods—using iflink, ip link, ethtool, and nsenter—to identify the corresponding host veth device for troubleshooting and management.
This comprehensive guide presents a systematic, step‑by‑step process for diagnosing JVM memory problems—including heap, Metaspace, DirectMemory, JNI memory, and stack issues—using Alibaba Cloud ARMS, ATP, standard JDK tools, and best‑practice commands to quickly locate root causes and apply effective solutions.
This article explains Kafka's fundamental components, version evolution, key monitoring metrics for producers, brokers, consumers and Zookeeper, and provides step‑by‑step troubleshooting methods for common issues such as slow topic throughput and message backlog.
This article lists the most frequent causes—such as an unstarted application, incorrect port listening, cloud security‑group settings, firewall rules, application‑level IP restrictions, network problems, and user‑side issues—and provides step‑by‑step commands and screenshots to help troubleshoot and restore access to cloud server ports.
This guide walks you through checking CPU usage, system load, process resources, tracing problematic processes, reviewing system logs, and using performance tools like perf to pinpoint and resolve Linux server bottlenecks.
This article walks through diagnosing why nvm use does not change the global Node.js version, explains how multiple Node installations can conflict, and provides a clear step‑by‑step solution—including installing nvm, checking versions, installing and switching targets, and removing stray Node binaries.
This guide explains why VMware Workstation 17.5 may lose keyboard and mouse control, provides configuration changes, a downgrade option, safe download sources, and verification steps to restore proper input functionality.
This article walks through a common Matplotlib title garbling issue caused by encoding settings, explains why the 'encoding' argument triggers an AttributeError, and provides a concise code fix using font configuration to display Chinese characters correctly.
When a production container suddenly hit over 90% CPU and excessive JVM garbage collection, the author walks through entering the pod, using top and top‑H to locate the offending thread, extracting its stack with jstack, downloading the data via a simple HTTP server, and ultimately discovering an Excel export routine that caused massive object allocation, fixing the code and restoring stability.
This guide walks you through the essential preconditions, core principles, and step‑by‑step procedures—including physical link checks, IP/DNS verification, gateway testing, public IP pinging, and DNS validation—using Windows and Linux commands to reliably diagnose and resolve network issues.
This guide walks you through ten practical steps for diagnosing Kubernetes problems, from POD startup failures and resource limits to network connectivity, storage configuration, container logs, DNS resolution, and final troubleshooting tips, helping you keep your clusters stable and reliable.
A detailed investigation of an Elasticsearch timeout incident reveals how an overly aggressive node_concurrent_recoveries setting caused CPU saturation, disk I/O spikes, and shard relocation overload, and outlines the steps taken to isolate the faulty node and restore cluster performance.
This article walks through a production incident where a Redis Cluster pipeline caused Dubbo threads to block and eventually deadlock, detailing the root‑cause analysis, code inspection, and verification steps using jstack, jmap, and MAT to confirm the deadlock and propose fixes.
This article walks through a Python web‑crawler error reported in a community chat, shows the original code snippet, explains how downgrading the Python version resolved the issue, and offers practical tips for sharing reproducible examples when seeking help.
The team traced read‑request timeouts to a single overloaded Elasticsearch node where an excessively high node_concurrent_recoveries setting caused many simultaneous shard recoveries and disk‑watermark‑driven relocations, and resolved the issue by lowering concurrent recoveries, enabling adaptive replica selection, and adjusting allocation settings.
This article walks through a real‑world investigation of a pod whose CPU spiked to over 90%, detailing how abnormal JVM garbage‑collection patterns were identified, traced to a specific Java thread, and resolved by fixing an inefficient Excel export routine.
This article explains why Redis may become slower, covering benchmark testing, high‑complexity commands, big keys, concentrated expirations, memory limits, fork overhead, huge pages, AOF settings, CPU binding, swap usage, memory fragmentation, and lazy‑free mechanisms, and provides practical optimization steps.
This guide walks through a systematic approach to diagnosing Kubernetes problems, covering pod startup failures, cluster health checks, event logs, pod status, network and storage verification, container logs, DNS service checks, and provides practical commands and tips for each step.
A sudden Kubernetes outage was traced to a CoreDNS ReadinessProbe failure on port 8181, and the article walks through symptom detection, code‑level root‑cause analysis, and a ConfigMap fix that restores inter‑pod communication.
This article explains what MySQL master‑slave replication lag is, walks through the replication workflow, identifies the main technical reasons for delay such as single‑threaded replay and lock contention, and provides concrete configuration and architectural solutions to reduce or eliminate the lag.
This guide covers a wide range of Docker problems—from migrating storage directories and handling disk space shortages to fixing network connectivity, container removal errors, and configuration issues—providing step‑by‑step commands, code snippets, and best‑practice solutions for reliable container management.
This guide walks you through ten systematic steps—from inspecting pod status and cluster health to verifying network connectivity, storage configuration, DNS resolution, and container logs—to effectively troubleshoot common Kubernetes issues and keep your applications running smoothly.
The article explains what MySQL master‑slave replication lag is, analyzes why it occurs—especially during relay‑log replay and large DDL/DML operations—and provides concrete configuration, hardware, and architectural solutions to reduce or eliminate the delay.
The article analyzes why a Java service repeatedly crashes around midnight in test environments, tracing the issue through system limits, Java version checks, cron job execution, strace logs, and Linux OOM killer behavior, and finally proposes configuration and version upgrades to prevent the failures.
After encountering latency spikes in a service, the article walks through systematic troubleshooting steps—examining module performance, resource metrics, and network latency—followed by detailed Redis diagnostics using metrics, latency commands, and profiling tools, ultimately recommending scaling, rate limiting, and caching strategies to resolve the issue.
This article walks through practical methods for troubleshooting slow service alerts, diagnosing Redis performance bottlenecks, and reproducing issues with local demos and load simulations, offering concrete metrics, command‑line checks, and mitigation strategies such as scaling, rate‑limiting, and pipeline optimization.
This article analyzes a common Git issue where a merge creates an empty commit that drops master changes, explains the underlying cause involving `git merge --continue` and `--allow-empty`, demonstrates reproduction steps, and provides mitigation strategies such as pre‑commit hooks and proper merge handling.
