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Reentrantlock Source Analysis 1--get unfair lock and fair lock () The most common way: View Code 1, for Reentrantlock need to master the following Reentrantlock creation (Fair lock/non-fair lock) Lock: Lock () Unlock: Unlock () Fi

Spin locks and mutex are two important concepts in concurrent programming. They are mainly used to lock shared resources to prevent Concurrent Data Access and ensure data consistency. But they also have some differences. This article mainly introduces these differences and describes when to use the spin lock and when to use the mutex lock. Theoretical Basis T

Why locks (concurrency control) are required. In a multiuser environment, multiple users may update the same record at the same time, which can create a conflict. This is the famous concurrency problem. Typical conflicts are:(1) Missing update: One transaction update overwrites the update result of other transactions, that is, the so-called update is lost. For example: User A changes the value from 6 to 2, and User B changes the value from 2 to 6, then user a loses his update. (2) Dirty read:

I. The background of the spin lock proposedBecause some resources in a multiprocessor system environment are limited and sometimes require mutually exclusive access (mutual exclusion), a lock mechanism is introduced, and only the process that acquires the lock can obtain access to the resource. that is, only one process can acquire a

Description: 1, personal technology is not a drop, also did not write threads in the project, the following are all based on their own understanding of the written. Therefore, only for reference and hope to point out the different views. 2, actually want to put the code of GitHub posted out, but still recommended in the beginner you write more personally, it is not posted out.I. BASIC INSTRUCTIONSClass, Object: ... (Don't know what to say, imaginative achievement here inexpressible >. Class lock

Http://www.infoq.com/cn/articles/java-memory-model-5 deep understanding of the Java Memory Model (v)--lock Http://www.ibm.com/developerworks/cn/java/j-jtp10264/Java Theory and Practice: a more flexible and scalable locking mechanism in JDK 5.0 http://blog.csdn.net/ghsau/article/details/7481142 1, Synchronized Declaring a block of code as synchronized has two important consequences, usually the code has atomicity (atomicity) and visibility (visibilit

The previous article introduces the lock that protects memory structure or variable in MySQL source code, and here we begin to introduce the table lock in MySQL transaction.Note 1: On the implementation of the table lock, the structure of "mutex+condition+queue" is used to implement the table lock function of concurren

Previous continuedA murder caused by a lock-free message queue: How to be a real programmer? (a)--ground: CauseA murder caused by a lock-free message queue: How to be a real programmer? (b)--month: Spin lockParallel spaceIn the copy of the above line I stopped first, is considered to occupy a position, although I know how to write, but the feeling is still very messy.I suddenly thought, since so tangled, so

Prior to Java5.0, only synchronized (built-in lock) and volatile. The display lock Reentrantlock is introduced after Java5.0. Reentrantlock OverviewThe Reentrantlock is a reentrant lock, which differs from the built-in lock, which needs to display the lock and unlock fo

Tags: read-only and tle sele generation process external HTTPS openNote: This article is reproduced from http://www.hollischuang.com/archives/934As described in the lock mechanism of a database, the task of concurrency control in a database management system (DBMS) is to ensure that the same data in the database is accessed simultaneously without disrupting the isolation and uniformity of the transaction and the consistency of the database.Optimistic

Oracle lock 1: DML lockDML lock, also known as data lock, is used to ensure data integrity when multiple users operate on data. DML lock prevents conflicting DML and DDL operations at the same time. DML Locks include Row Locks (TX) and Table Locks (TM). Different DML operations will automatically request the correspond

This article from: http://blog.163.com/hbu_lijian/blog/static/126129153201261722410353/ Kernel synchronization measures (for Linux kernel) To avoid concurrency and prevent competition. The kernel provides a set of Synchronization Methods to protect shared data. Our focus is not to introduce the detailed usage of these methods, but to emphasize the difference between these methods and them.The synchronization mechanism used in Linux has been continuously improved since 2.0 to 2.6. From the initia

A bloodcase caused by a lock-free Message Queue: how to be a real programmer? (2) -- month: spin lock, queue spinPrefix A bloodcase caused by a lock-free Message Queue: how to be a real programmer? (1) -- location: Cause A bloodcase caused by a lock-free Message Queue: how to be a real programmer? (2) -- month: spin lo

With the frontline synchronization only know the Synchronize keyword, then know that there is a lock, why also have a lock to achieve synchronization? Synchronized's limitations occupy the lock thread waiting for IO or other reasons to be blocked, without releasing the lock, Read and read can also conflict when other t

One: OverviewCompared with other databases, MySQL's locking mechanism is relatively simple, and its most notable feature is that different storage engines support different locking mechanisms. For example, the MyISAM and memory storage engines use table-level locks (table-level locking), InnoDB storage engines support row-level locks (row-level locking) and table-level locks, but row-level locks are used by default.MySQL main two types of lock charact

In the database lock mechanism, the task of concurrency control in a database management system (DBMS) is to ensure that multiple transactions simultaneously access the same data in the database without disrupting the isolation and uniformity of the transaction and the consistency of the database. Optimistic concurrency control (optimistic lock) and pessimistic concurrency control (pessimistic

In addition to Spinlock, the Linux kernel also has a spin lock called arch_rwlock_t. Its header file is Qrwlock.h, contained in Spinlock.h, which is called "Queue read/write lock" in the header file. This lock implements a read-write lock using only two member variables. A spinlock, and a shaping

In Java multithreading, you can use the keyword synchronized to implement a mutex between threads. After JDK1.5, a thread concurrency library java.util.concurrent is provided to manipulate multiple threads, including java.util.concurrent.atomic and Java.util.concurrent.lock. Atomic can realize the atomic operation of data or variable, and lock can achieve thread mutual exclusion, can realize read-write lock

Turn InnoDB row-level locksInnoDB Row-level locksCategory: Database 2013-03-13 16:40 1745 people read comments (0) favorite reports Nnodb lock mode and lock methodInnoDB implements the following two types of row locks.? Shared Lock (S): Allows a transaction to read one line, preventing other transactions from acquiring an exclusive

With the development of the Internet, more and more Internet enterprises are confronted with the concurrency security problems caused by the expansion of user volume. This paper mainly introduces several kinds of locking mechanisms common in Java concurrency.1. Bias Lock　The bias lock is a mechanism of lock optimization proposed by JDK1.6. The core idea is that i