ledger locks

Analysis of Inter-thread communication 2: read/write locks and spin locks, analysis of spin The mutex and condition variables are used for thread synchronization. This article discusses the use of read/write locks and spin locks, and provides the corresponding code and precautions, the relevant code can also be found i

OracleDatabasePessimistic lockAndOptimistic lockIs what we will introduce in this article. Sometimes, for maximum performance, databases generally have a concurrency mechanism, but the problem is Data Access conflicts. To solve this problem, most databases Use Data Locking. There are two methods to lock data: Pessimistic lock and optimistic lock. What is a pessimistic lock? A pessimistic lock, as its name implies, is a pessimistic attitude towards data conflicts. That is to say, assume that data

In this article, we mainly focus on key-range lock. Key-range lock has s-s, S-u, I-n, X-X several situations. One by one, we strive to understand. Unfortunately, the deadlock analysis may be prolonged. Acquisition rules for range S-S locks Msdn partially describes the range lock rules, but it is concise. Below we will separate various situations and clarify the rules involved or not involved in msdn, these rules apply to SQL Server 2000/2005/2008/200

Application scenarios and scenarios of optimistic locks and pessimistic locks Locking)During the implementation of business logic, data access needs to be exclusive. For example, end computing on the day of the Financial SystemProcessing, we want to process the data at a cut-off time point, rather than in the settlement process.(Several seconds or several hours), and the data changes again. In this case, w

Lock(Locking)During the implementation of business logic, data access needs to be exclusive. For example, in the daily final computing process of the financial system, we want to process the data at a cut-off time point instead of the settlement process (which may be several seconds, or several hours), and the data changes again. At this point, we need to use some mechanisms to ensure that the data will not be modified by the outside world during an operation. This mechanism is called a "Lock" h

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 count changes to 1. The count increments whenever this same task (thread) Gets a lock

control is the kind of problem to solve.Blocking, timestamp, optimistic concurrency control (optimistic lock) and pessimistic concurrency control (pessimistic lock) are the main techniques used in concurrency control.2 Concept IntroductionLock type:Read lock: Shared lock, can be shared by multiple read operations, can only be shared to read.Write lock: Exclusive lock;Size of Lock:Table Lock: Locks are applied at the table level, concurrency is low, a

, shared) provided in the data. In fact, in DBMS, pessimistic lock is implemented by using the lock mechanism provided by the database itself. Below to learn the pessimistic lock and optimistic lock respectively.Pessimistic lock In the relational database management system, pessimistic concurrency control (aka "Pessimistic lock", pessimistic Concurrency control, abbreviated "PCC") is a method of concurrency control. It can prevent a transaction from modifying the data in a way that affe

PHP implementation code for common locks and locks under concurrency. This is the case in recent projects. 1. when a file is generated, multiple users have the permission to generate the file to prevent errors in the generated results due to concurrency. in this case, you need to perform the generation process in the latest project. 1. when a file is generated, multiple users have the permission to generate

Latch locks and tlock (transaction locks), DML lock rules, and deadlock analysis in MySQL.I. The relationship between latch and TlockLatch: Designed to protect the correctness of critical resources, such as protecting the memory pages that are being used from being destroyed.There is no deadlock detection mechanism, a lightweight lock, and a memory page or memory sharing variable when the object is in effec

into two types: Read lock and Write lock. If a thread obtains a read lock, the other thread that performs the read operation can continue to acquire the read lock, which means that the read operation can be executed concurrently, but the other write locks will be blocked. If a thread obtains a write lock, any other threads that attempt to acquire read and write locks are blocked.Let's look at an example:Im

Locking) During the implementation of business logic, data access needs to be exclusive. For example, end computing on the day of the Financial System Processing, we want to process the data at a cut-off time point, rather than in the settlement process. (Several seconds or several hours), and the data changes again. In this case, we need to use some machines This mechanism ensures that the data is not modified by the outside world during an operation. To lock the data of the selected

Original: http://blog.csdn.net/l1028386804/article/details/735238101. Can be re-entered lock (Reentrant lock)Redisson's distributed reentrant lock Rlock Java object implements the Java.util.concurrent.locks.Lock interface, and also supports automatic expiration unlocking.[Java]View PlainCopy Public void Testreentrantlock (Redissonclient redisson) { Rlock lock = Redisson.getlock ("AnyLock"); try{ //1. The most common way to use //lock.lock (); //2. Support expired unlock function,

This article mainly introduces the deadlocks, reentrant locks, and mutex locks in Python. although Python GIL problems in thread programming are commonplace, you can refer I. deadlock To put it simply, a deadlock occurs when a resource is called multiple times, and a deadlock occurs when the resource is not released by multiple callers. here we use examples to illustrate the two common deadlocks. 1. iterat

Implement read/write locks and read/write locksExclusive lock disadvantagesData is shared among multiple threads. The common practice is to lock read/write, that is, only one thread can read or write data at the same time point to ensure data consistency, that is, thread security. For example, the following pseudocode is a common practice. 1 void Read () 2 {3 Lock (mutex); 4 5 // Read data 6 7 UnLock (mutex); 8} 9 10 void Write () 11 {12 Lock (mutex);

When synchronized modifies a static method, a class lock (that is, the class itself, note: it is not an instance) is obtained under multiple threads ),The scope of action is the entire static method, and the target object is all objects of this class.When synchronized modifies a non-static method, the object lock (the Instance Object of the class) is obtained under multiple threads ),The function scope is the entire method. The function object is the object that calls the method.Conclusion: Diff

Id is the primary key. Are the following statements row locks or table locks? First sentence: updateTablesetX1whereIdIN (100,); second sentence: updateTablesetX1whereIdBetween1AND10; third sentence: updateTablesetX1whereId gt; 1 ANDId lt; mysql innolock DB Id is the primary key. Are the following statements row locks or table

(); } finally { lock.unlock (); } }Redisson also provides methods for asynchronous execution of distributed locks: public void Testasyncreentrantlock (Redissonclient redisson) { Rlock lock = Redisson.getlock ("AnyLock"); try{ Lock.lockasync (); Lock.lockasync (timeunit.seconds); future 2. Fair Lock (Fair Lock) Redisson Distributed Reentrant Fair Lock is also a Rlock object to implement the Java.util.concurrent.locks.Lock interface. Whe