function lock

MySQL lock usage-row-Level Lock is the smallest lock in MySQL, which can greatly reduce database operation conflicts. However, the smaller the granularity, the higher the implementation cost. The MYISAM engine only supports table-level locks, while the INNODB Engine supports row-level locks. The following content is also for INNODB row-level locks. Row-level lock

Pessimistic lock Introduction (encyclopedia): A pessimistic lock, as its name implies, is conservative in that the data is modified by the outside world (including other transactions of the system, as well as transactions from the external system), so that the data is locked during the entire process of processing. Pessimistic lock implementation, often rely on t

Tags: name water hang Process Control point for SNAP isolation level(in order to facilitate, the English keywords are used in lowercase, the relevant knowledge points will be introduced briefly, strive to be able to read independently)At the beginning of the article I will first introduce the following knowledge points required in this article: Knowledge of InnoDB clustered index (clustered index) and non-clustered index (two-level index, nonclustered index) Isolation level for INNO

Android app. Samsung i9000 series tutorial (2). Engineering Code, network lock and Lock three keys Papaya 20110401 I. Engineering Code The project code provided by i9000 is very useful, as follows.(The content is organized on the network. The original author is unknown) Dial Input * #0 * # mobile phone test (recommended purchase test)Line 1 red green blue (primary color test)Line 2 melody vibrate dimming)Li

Win7 System computer keyboard SCROLL LOCK SCROLL LOCK key how to use? The specific methods are as follows: 1, first scroll LOCK button in the upper right of the computer; 2, Scroll lock button name called ' Lock rolling Screen ', in fact, is to

/** * @author Admin * @date 2018/1/12 9:48 * Function on the same instance object to discuss * synchronized Synchronous method Test * Two threads, one thread calls synchronized adornment method, another thread can call non s Ynchronized modified method, non-impact */public class Synchronizedtest {public synchronized void MethodA () {try {fo R (int i = 0; i /** * @author Admin * @date 2018/1/12 10:16 *

[Guide: The basic theory of locks used in various large databases is consistent, but there are differences in the implementation. SQL Server emphasizes that the locks are managed by the system. When the user has a SQL request, the system analyzes the request, automatically in satisfying the lock condition and the system performance for the database with the appropriate lock, while the systems are often auto

A recently maintained network server encountered performance problems, so it made major changes to the original program framework. Most of the changes are the thread working mode and data transmission mode. The final result is to change the lock usage mode. After some improvement, the GMB Nic can basically work at full speed. After the performance was up to standard, I was wondering if I could use a more lightweight

Mainly talk about the performance of the lock and some other theoretical knowledge, the main source of the content is "Java Concurrency in Practice", combined with their own understanding and practical application of the lock mechanism to a small summary.One of the first things to emphasize is that all locks (including built-in locks and advanced locks) are performance-intensive, that is, in high concurrenc

Mainly talk about the performance of the lock and some other theoretical knowledge, the main source of the content is "Java Concurrency in Practice", combined with their own understanding and practical application of the lock mechanism to a small summary.One of the first things to emphasize is that all locks (including built-in locks and advanced locks) are performance-intensive, that is, in high concurrenc

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

pool in Java, so the lock private variable for these threads actually points to the same area in the heap memory, which holds the area of the lock variable in the main function, so the object lock is unique and shared. Thread Sync!! Here the synchronized lock is the string

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:

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

by Linux developers than to understand the code they write, but it is clear that the automatic release of large kernel locks in the Schedule () function has complicated the problem. Let's take a look at the operations on the large kernel lock in Schedule: Linux_2.6.34/kernel/sched. c 1 /* 2 * Schedule ()Is the main SchedulerFunction. 3 */ 4 asmlinkage void _ sched schedule (void) 5 { ... 19Release

can not be acquired when the system overhead, so the acquisition of locks and release locks of the interval code execution time should be as short as possible.2. In a single CPU core preemption system, kernel preemption is forbidden during spin lock hold. However, in a single CPU core does not support preemption system, spin lock degradation is null operation. -that is, if the interval code that holds the

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

. * * void unlock (); } From the lock interface we can see that there is a main method, the function of these methods can be seen from the annotation: Lock (): Gets the lock and waits if the lock is taken up Unlock (): Release

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