idn locks

This article describes how to handle the problem. net locks six methods. First, let's discuss the concurrency problem, and then discuss the three methods to deal with optimistic locks. Optimistic locks cannot solve the concurrency problem from the root, therefore, we will introduce pessimistic locks later. Finally, we

lock. There are two basic types of locks in the database: exclusive locks (Exclusive Locks, i.e., x locks) and shared locks (Share Locks, or S locks). When a data object is added to t

manages resources and locks, SQL Server not only manages locks, You also manage compatibility or escalation locking between lockdown modes and resolve deadlock issues. With SQL Server's powerful, granular locking mechanism, concurrency performance is maximized, but using as few system resources as possible is what we want most. There are two kinds of locking system: One is locking the shared data, which is

Differences between semaphores and spin locks The spin lock does not cause the caller to sleep.If the spin lock has been maintained by another execution unit, the caller will keep repeating to check whether the lock holder has released the lock. "Spin" means "in situ ".The semaphore causes the caller to sleep.It will drag the process out of the running queue unless the lock is obtained. ------------------------------------------------------Although th

In the actual production environment, if the concurrency is not large, you can use the pessimistic locking method. This method is very convenient and simple to use. However, if the system concurrency is very large, pessimistic locking will bring about a very large performance problem, so we need to choose an Optimistic Locking method. Pessimistic locks assume that other users attempt to access or change the objects you are accessing and changing have

protected dataOther users can still access the service normally, such as deleting and updating the service. Therefore, although the above two methods can ultimately achieve this requirement, it will greatly affect otherThe user's normal use. Therefore, these two methods are not recommended by the author. I recommend that you use row-level locks. Next I will elaborate on this method in detail, with special emphasis onMeaning. For example, there are tw

How to Use locks intelligentlyTips for using locks efficiently in Java Document options Valign = "TOP"> Width = "122">

Read/write locks in Java concurrent packages and their Implementation Analysis 1. Preface Usually used locks such as ReentrantLock in Java concurrent packages are usually exclusive locks. These locks can be accessed by only one thread at a time, the read and write locks can

Every time you talk about locks and blocks in SQL Server (Locking Blocking): Why do we need to update locks in SQL Server? Before we explain the reasons for specific needs, first I want to introduce you to the next time when the update lock (lock) is obtained, according to its compatibility lock itself is how to deal with. In general, when an UPDATE statement is executed, SQL Server uses an update lock. I

Serialization (Serializable): lowest performance, range lock causes concurrency degradation Snapshot (snopshot): This is done by creating an additional copy in tempdb to avoid dirty reads, non-repeatable reads, which can impose additional burdens on tempdb Mode of Lock shared lock (S lock): used to read the lock added by the resource. A resource that has a shared lock cannot be modified. Shared locks are read by de

1ObjectiveThe database large concurrency operation takes into account the deadlock and lock performance issues. See online most vague (especially update lock), so here is a concise explanation, for the following description of the convenient, here with T1 for a database execution request, T2 represents another request, can also be understood as T1 a thread, T2 for another thread. T3,t4 and so on. The following is an example of SQL Server (2005).2Types of Loc