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The article demonstrates that synchronizing on a locally created object does not provide proper thread safety, shows the resulting chaotic output, and explains how moving the lock object to a class field resolves the issue, illustrated with Java code and debugging screenshots.
This article explains how Java's synchronized keyword works, covering object and class locks, lock upgrades such as biased, lightweight, and heavyweight locks, the underlying monitor implementation, example code for a thread‑safe counter, and performance considerations for high‑concurrency scenarios.
This article examines the evolution of Java's ConcurrentHashMap, comparing the segment‑lock implementation in Java 7 with the CAS‑plus‑synchronized, bucket‑level locking and red‑black tree enhancements introduced in Java 8, covering lock mechanisms, data structures, resizing strategies, core operations, performance and suitable use cases.
This article explains MySQL's three concurrency types—read‑read, read‑write, and write‑write—describes how InnoDB uses MVCC, shared and exclusive locks, and provides practical examples and code for handling update‑loss and write‑write conflicts with optimistic and pessimistic locking.
The article explains five fundamental concurrency levels—Blocking, Starvation‑Free, Obstruction‑Free, Lock‑Free, and Wait‑Free—detailing their definitions, implementation mechanisms in Java, performance trade‑offs, suitable scenarios, and practical decision guidance for building high‑performance, reliable systems.
This comprehensive guide explores why locks are essential in concurrent programming, explains the principles behind mutexes, semaphores, read‑write locks, and re‑entrant locks, provides Python code examples, discusses common pitfalls like deadlocks, and offers best‑practice strategies for production environments.
KeyDB, a Redis fork, replaces the single‑threaded architecture with a multi‑threaded model using a main thread and worker I/O threads, SO_REUSEPORT, per‑thread connection management, fastlock spin‑lock mechanisms, and active‑replica support, enabling concurrent data access and improved performance.
After publishing 50 installments of the 'MySQL Core Modules' series covering transactions, locks, and undo, the author expresses gratitude to readers and the community, outlines upcoming articles on Undo, MVCC, and Redo, and reviews past content while planning a compiled book.
This article demonstrates how to simulate a high‑concurrency flash‑sale scenario using SpringBoot, MySQL, Mybatis‑Plus and JMeter, analyzes the overselling problem caused by premature lock release, and presents seven solutions—including lock‑first strategies, AOP, pessimistic and optimistic locks, and queue‑based approaches—along with code samples and test results.
This article examines how InnoDB acquires various row, gap, and next‑key locks during INSERT … ON DUPLICATE KEY UPDATE statements under REPEATABLE‑READ and READ‑COMMITTED isolation levels, illustrating the lock behavior with detailed SQL examples and performance‑schema queries.
This article examines how InnoDB acquires row‑level locks during INSERT … ON DUPLICATE KEY operations under REPEATABLE‑READ and READ‑COMMITTED isolation levels, explains the lock types on primary and unique indexes, and shows the rollback and lock‑conversion process with concrete SQL examples.
This article explains how MySQL 8.0.32 InnoDB handles INSERT … ON DUPLICATE KEY UPDATE under REPEATABLE‑READ and READ‑COMMITTED isolation levels, showing the preparation steps, lock acquisition process, and why the same exclusive record lock is obtained in both cases.
The article examines how frequent inventory adjustments in JD retail supply‑chain can suffer from concurrency issues, explains why traditional locking may fail, analyzes a real‑world case of lock misuse, and presents code‑level, database‑level, and architectural solutions to guarantee data consistency.
This article reproduces a MySQL 8.0.32 InnoDB deadlock using two concurrent DELETE statements on the same secondary index, explains the lock types and lock‑wait graph, and details why the deadlock occurs and how it is resolved.
This article demonstrates how InnoDB acquires different types of row and gap locks under REPEATABLE-READ and READ-COMMITTED isolation levels by creating a test table, inserting data, setting transaction isolation, executing SELECT ... FOR SHARE statements, and inspecting lock information from performance_schema.
This tutorial demonstrates, using MySQL 8.0.32 InnoDB source code, how REPEATABLE-READ and READ-COMMITTED isolation levels affect the locking behavior of SELECT ... FOR SHARE statements on primary‑key rows, including preparation, execution, and detailed lock analysis.
This article examines how MySQL 8.0.32 InnoDB handles locking when inserting a row that violates a unique index under the READ‑COMMITTED isolation level, detailing the preparation steps, observed lock types, the underlying mechanism, and the final cleanup actions.
This article examines how InnoDB handles row locking when an INSERT triggers a primary‑key index conflict, detailing the lock types on primary and unique indexes, the implicit‑to‑explicit lock conversion, and the role of the supremum record in the locking process.
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 article explains how InnoDB in MySQL 8.0.32 grants table and row locks, detailing the active versus passive acquisition, the lock‑granting algorithms for tables and rows, and the priority, weight, and FIFO rules that determine lock ordering and deadlock handling.