kiosk lock

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

Tags: check log eric Share blog exclusive pessimistic lock good usesql-optimistic lock, pessimistic lock in the concurrency Every time you write a blog, the first sentence is this: the programmer is very hard, in addition to writing procedures, but also to write a blog! Of course, hope that the future day, a boss see this blog, to your programmer staff pay bar! B

Mysql Innodb Lock Mechanism and mysqlinnodb Lock MechanismLatch and lock Latch can be considered as a lock in an application. It can be called a latch (lightweight lock) because it requires a very short lock time. If the

Every time you write a blog, the first sentence is this: the programmer is very hard, in addition to writing procedures, but also to write a blog! Of course, hope that the future day, a boss see this blog, to your programmer staff pay bar! Because the programmer's world is silent except bitter force. Most of the programmers in my eyes do not love to talk, silently bear the great pressure of programming, in addition to technical exchanges, they do not want to be good at communicating with others,

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

I have never carefully understood the UPDATE lock. I recently saw a problem on the MSDN forum asking about the deadlock issue of heap table UPDATE. The problem is very simple. There are tables and data like this: Create table dbo. tb ( C1 int, C2 char (10 ), C3 varchar (10) ); GO DECLARE @ id int; SET @ id = 0; WHILE @ id BEGIN; SET @ id = @ id + 1; INSERT dbo. tb VALUES (@ id, 'B' + RIGHT (10000 + @ id, 4), 'C' + RIGHT (100000 + @ id, 4 )); END; Per

Basic ConceptsIn this chapter, we will explain the principle of "thread access to Fair lock", and we need to understand a few basic concepts before explaining it. The following are all based on these concepts, which may be tedious, but from these concepts, you can see some of the architecture of the Java lock, which is helpful for us to know about locks.1. AQS -refers to the Abstractqueuedsynchronizer class

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

Go to: http://blog.sina.com.cn/s/blog_6d7fa49b01014q7p.htmlMany people ask this question, what does the Linux kernel do to provide a variety of synchronization lock mechanisms? Traced is actually due to the existence of multiple processes in the operating system concurrent access to shared resources, resulting in the race between processes. These include the SMP system we know, the competing resources between multiple cores, the competition between si

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,

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

Locking mechanism used in multiple CPU systems, when a CPU is accessing the critical section of the spin lock protection, the critical section will be locked, the other need to access the critical section of the CPU can only busy wait until the previous CPU has access to the critical section, the critical section unlocked. The spin lock allows the waiting thread to wait for the busy waits instead of sleep b

This article mainly introduced the PHP program in the file lock, mutual exclusion lock, read-write lock using skills analysis, which focuses on the Sync module and pthreads module use examples, the need for friends can refer to. We hope to help you. File lockFull name advisory file lock, which is mentioned in the book

Original: Lock-free data structure (LOCK-FREE data structures)One weeks ago, I wrote an article about the latch (latches) and spin lock (Spinlocks) in SQL Server. The 2 synchronization primitives (synchronization primitives) are used to protect shared data structures in SQL Server, such as pages in the cache pool (via a latch (latches)), and locks in the

1. PrefaceMultithreaded programming, we not only want to be able to achieve a logical sequencing between two threads, but also want to two unrelated threads when accessing the same resource, while only one thread can operate on the resources, otherwise there will be unpredictable results.For example, there are two threads need to add 1 to the same counter, we want the result is the counter finally add 2, but may also get to this counter, the first thread to the counter plus 1, but the second thr

Hibernate supports two types of locking mechanisms:The "Pessimistic lock (pessimistic Locking)" and "optimistic Lock (optimisticlocking)" are usually called. Pessimistic lock implementation, often rely on the database provided by the lock mechanism (also only the database layer provides a

One weeks ago, I wrote an article about the latch (latches) and spin lock (Spinlocks) in SQL Server. The 2 synchronization primitives (synchronization primitives) are used to protect shared data structures in SQL Server, such as pages in the cache pool (via a latch (latches)), and locks in the Lock Manager hash table (via a spin lock (Spinlock)). Next you will se