lock computer

The above discusses the mutex and conditional variables used for thread synchronization, this article will discuss the use of read and write locks and spin locks , and give the corresponding code and considerations, the relevant code can also be downloaded on my GitHub . read/write lock The mutex is either locked or unlocked, and only one thread can lock it at a time, while a read-write

Note: 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 concurrency control (optimistic

Turn from: http://blog.csdn.net/javazejian/article/details/75043422 From "Zejian's blog." Related articles: Deep understanding of Java type information (class object) and reflection mechanism Deep understanding of Java Enum Types (enum) Deep understanding of Java Annotation Types (@Annotation) Deep understanding of the Java Class loader (ClassLoader) Deep understanding of the synchronized implementation principle of Java concurrency Java concurrent Programming-non-

Multi-thread pessimistic lock, optimistic lock, multi-thread 1. pessimistic lock, as it is called, refers to a conservative attitude towards data being modified by the outside world (including other transactions of the current system, as well as transactions from the external system). Therefore, the data is locked during the entire data processing process. Pessim

Tags: c blog http a COM strongIn the database, concurrency control has optimistic lock and pessimistic lock between, when with optimistic lock compare good when with pessimistic lock?In the actual production environment, if the concurrency is not small, can use pessimistic locking method, this method is very convenient

The case lock and number lock icons are always displayed on the desktop, as shown in the figure: Operation Steps: 1. Right-click on the desktop space, select "Screen resolution"; 2. Select "Advanced Settings"; 3. Select the "Screen display" tab; 4. This tab allows you to see a "digital lock and Case

1. application. Lock and application. Unlock are usually paired to lock allCode(Do not lock the assignment to the application ). 2. Lock (OBJ) is used to lock the OBJ object. The OBJ object must be a global object (for example, application ). Application.

Lock, lock 1. view the current Lock ObjectSelect a. owner,A. object_name,B. xidusn,B. xidslot,B. xidsqn,B. session_id,B. oracle_username,B. OS _user_name,B. process,B. locked_mode,C. machine,C. status,C. server,C. sid,C. serial #,C. programFrom all_objects,V $ locked_object B,V $ session cWhere (a. object_id = B. object_id)And (B. process = c. process)Order by 1,

possible, you can insert the records into the staging table and then periodically update the data in the staging table to the actual tables. This can be accomplished with the following command:Copy CodeThe code is as follows:mysql> LOCK TABLES real_table Write, insert_table write;Mysql> INSERT into real_table SELECT * from insert_table;mysql> TRUNCATE TABLE insert_table;Mysql> UNLOCK TABLES;The advantages of row-level locks are:Reduce conflict locks

Reprint: http://blog.csdn.net/sunp823/article/details/49886051The state of the lock: lock-free, biased, lightweight, and heavy-lock.The bias lock applies to scenarios where only one thread accesses the synchronization block.Lightweight locks, competing threads do not block, and are suitable for holding locks for a relatively short period of time. A thread that do

The last tool in the lock is introduced from this section: read-write Lock (Readwritelock).Reentrantlock implements a standard mutex, which is the notion that only one thread can hold a lock at a time, or the so-called exclusive lock. This feature has been emphasized in the previous chapters. Obviously this feature red

Another mechanism for implementing thread synchronization or mutual exclusion in Java 5 is the use of lock. Lock is more object-oriented than the synchronized method in the traditional threading model.Mutual-exclusion lock –lock (Reentrantlock)A mutex is a lock that can be h

How to lock a row table database 1 how to lock a row of a table SET transaction isolation level read uncommitted Select * from Table rowlock where id = 1 2. Lock a table in the database Select * from table with (holdlock) Lock statement:SYBASE:Update table set col1 = col1 where 1 = 0;MSSQL:Select col1 from table (tabl

How do I set the win10 screen lock screen image ?, Win10 screen lock screen image Windows 10 has been in use for some time for many users, but it is not so easy to use at the beginning. After all, it is quite different from the previous xp, Windows 7, and other systems. I believe many people care about the appearance of the screen lock interface and want to set

Lock (Locking)In the process of implementing business logic, it is often necessary to guarantee the exclusivity of data access. As in the final settlement of the financial system, we want to process the data for a cut-off point in time, and we do not want the data to change again during the settlement process (which may be a few seconds or maybe a few hours). At this point, we need some mechanism to ensure that the data will not be modified in the pro

The recent accidental discovery before the pessimistic lock optimistic lock understanding is wrong, so re-study a bit.1. Pessimistic lockPessimistic lock Introduction (encyclopedia):Pessimistic locking, as its name implies, is a conservative attitude to the data being modified by the outside world (including other transactions currently in the system, as well as

In concurrent environments, you can consider the use of lock mechanisms when resolving shared resource conflict issues. 1. Object Lock All objects automatically contain a single lock. The JVM is responsible for tracking the number of times an object is locked. If an object is unlocked, its count becomes 0. When a task (thread) locks an object for the first time,

the way the Win7 system laptop locks the screen is as follows: Method one: On your own Win7 system computer desktop, select Click to Start menu options, click the menu options after the column we find the Control Panel tool options, click Open, Pop-up Control Panel window options, select the keyboard icon options inside, click on the open after we select the hardware settings, the option to close can be selected. Win7 system Method Two: Ther

Java thread fair lock ReentrantLock (boolean fair), reentrantlock fair lockI. Fair lock 1. Why is there a fair lock? The CPU selects a thread randomly while waiting for the queue to schedule the thread. Because of this randomness, the thread cannot be guaranteed first-come-first-served (the lock controlled by synchroni

Two types of locks are available in the Java Reentrantlock constructor: Create fair and unfair locks (default). The code is as follows:Public Reentrantlock () {Sync = new Nonfairsync ();}Public Reentrantlock (Boolean fair) {Sync = Fair? New Fairsync (): New Nonfairsync ();}In the fair lock, the thread acquires the lock in the order in which they make the request, but in the unfair