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Xiao Lou's Tech Notes

Backend technology sharing, architecture design, performance optimization, source code reading, troubleshooting, and pitfall practices

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Latest from Xiao Lou's Tech Notes

79 recent articles

Xiao Lou's Tech Notes

Nov 9, 2021 · Backend Development

Master Reactive Spring: Essential Resources and Insights for Beginners

This article recommends a comprehensive CSDN blog series on reactive Spring, detailing beginner‑friendly explanations of reactive programming, lambda and functional concepts, testing tips, performance insights, and includes vivid CPU‑I/O analogies, plus useful links to the Reactor 3 manual and Apache Shenyu gateway.

Javabackend developmentmicroservices

0 likes · 7 min read

Master Reactive Spring: Essential Resources and Insights for Beginners

Xiao Lou's Tech Notes

Nov 2, 2021 · Backend Development

Why My Custom Dubbo LoadBalance Stopped Working and How to Fix It

The article recounts a puzzling case where a custom Dubbo load‑balance extension (XLB) stopped being applied, explains how conflicting XML and Spring‑Boot configurations caused the consumer to ignore the custom setting, and walks through the source‑code investigation that reveals the loading order and caching behavior, ending with a concise summary of the root cause and resolution.

ConfigurationDebuggingDubbo

0 likes · 8 min read

Why My Custom Dubbo LoadBalance Stopped Working and How to Fix It

Xiao Lou's Tech Notes

Oct 12, 2021 · Databases

Optimizing ORDER BY/LIMIT in Sharded Databases with Cobar’s Algorithm

This article explains Cobar’s sharding middleware and presents an optimization technique for handling ORDER BY and LIMIT queries across multiple databases, detailing the original approach, its inefficiencies with deep pagination, the step‑by‑step improved algorithm, performance analysis, limitations, and practical applicability.

CobarLIMITOrder By

0 likes · 8 min read

Optimizing ORDER BY/LIMIT in Sharded Databases with Cobar’s Algorithm

Xiao Lou's Tech Notes

Sep 27, 2021 · Backend Development

How a Dubbo 2.7.12 Bug Caused Memory Leaks and Service Outages – Diagnosis and Fix

After a late‑night incident where a Dubbo 2.7.12 service crashed, the author traced high memory and CPU usage to a full GC spike, identified a HashedWheelTimer thread‑pool bug causing request timeouts to be missed, reproduced the leak, and confirmed the issue was fixed in Dubbo 2.7.13.

DubboHashedWheelTimerJava

0 likes · 7 min read

How a Dubbo 2.7.12 Bug Caused Memory Leaks and Service Outages – Diagnosis and Fix

Xiao Lou's Tech Notes

Jul 21, 2021 · Backend Development

Mastering Dubbo Generic Calls with Go: From Telnet to Dubbo-go

This article explains how to test and invoke Dubbo services without provider JARs by using telnet or generic calls, compares Java and Go implementations, details the underlying filters, and provides practical code samples for building a Dubbo-go based gateway or testing platform.

DubboGeneric InvocationJava

0 likes · 9 min read

Mastering Dubbo Generic Calls with Go: From Telnet to Dubbo-go

Xiao Lou's Tech Notes

Jul 6, 2021 · Databases

Inside Cobar’s SQL Parser: AST Structure, Traversal, and Real‑World Uses

This article explains how Cobar’s SQL parser converts SQL statements into an abstract syntax tree (AST), details the parser’s implementation options, demonstrates AST node definitions and visitor‑based traversal in Java, and explores practical applications such as sharding, feature extraction, and dangerous‑SQL interception.

ASTCobarDatabase Middleware

0 likes · 8 min read

Inside Cobar’s SQL Parser: AST Structure, Traversal, and Real‑World Uses

Xiao Lou's Tech Notes

Jun 9, 2021 · Backend Development

Mastering Nacos Configuration Center: Architecture, Setup, and Advanced Features

This article explains the purpose, requirements, architecture, setup steps, configuration model, client workflow, request protocol, data storage, gray release, and rollback mechanisms of Nacos's configuration center, providing a comprehensive guide for backend developers.

Config ManagementNacosconfiguration center

0 likes · 9 min read

Mastering Nacos Configuration Center: Architecture, Setup, and Advanced Features

Xiao Lou's Tech Notes

May 8, 2021 · Backend Development

Graceful Shutdown of RocketMQ Consumers in Spring: A Real-World Debugging Tale

In a late-night deployment, the author traced a persistent ‘DataSource already closed’ error to an ungraceful RocketMQ consumer shutdown, explored Spring’s ShutdownHook behavior, and ultimately implemented a SmartLifecycle-based solution for orderly bean destruction.

Graceful ShutdownJavaRocketMQ

0 likes · 7 min read

Graceful Shutdown of RocketMQ Consumers in Spring: A Real-World Debugging Tale

Xiao Lou's Tech Notes

Apr 28, 2021 · Backend Development

Why Does Dubbo 2.7.3 Throw Duplicate Unregister Errors and How to Fix It

This article investigates the duplicate unregister bug in Dubbo 2.7.3, explains how the shutdown hook interaction causes the error, and shows how the issue was fixed in later versions and can be mitigated without upgrading the whole framework.

Bug FixDubboDuplicate Unregister

0 likes · 8 min read

Why Does Dubbo 2.7.3 Throw Duplicate Unregister Errors and How to Fix It

Xiao Lou's Tech Notes

Apr 2, 2021 · Backend Development

Why Upgrading Dubbo 2.6 to 2.7 Can Trigger ‘No Provider’ Errors and How to Resolve Them

Upgrading a Dubbo consumer from 2.6.6 to 2.7.3 can break version matching with providers, leading to “No provider” errors, and the article explains the root cause, code differences, and why the 2.7.7 fix may still fail.

Java RPCVersion Compatibilitybackend upgrade

0 likes · 6 min read

Why Upgrading Dubbo 2.6 to 2.7 Can Trigger ‘No Provider’ Errors and How to Resolve Them