kiosk lock

class at the same time.6 The . Synchronized keyword cannot be inherited, that is, the method of the base class synchronized F () {} is not automatically synchronized F () {} in the inheriting class, but instead becomes F () {}. Inheriting a class requires that you explicitly specify one of its methods as the Synchronized method. 7. When a global object or class is locked, all objects of that class function.Class Lock ExampleTo

The more obvious the advantage of threads in the multi-core era over the past month, the learning of multi-threaded programming is also on the agenda. But more and more people are stuck in the thread Quagmire, and finally they are totally confused. There are more and more deadlocks and more abnormal data. In the concurrency test, let one threadProgramEmployees are overwhelmed. "I have nothing to do in my own programming environment, and there will be no errors in single-step debugging. When two

File lockThe name is advisory file lock, which is mentioned in the book. This type of lock is more common, such as MySQL, PHP-FPM Boot will have a PID file records the process ID, this file is a file lock. This lock prevents a process from running repeatedly, such as limiting the execution of a task every minute when

Tags: lock pos process Resources style-o lrzsz apt-get commandInstall the software under Ubuntu16.04, for example: sudo apt-get install Lrzsz when prompted:　　Unable to get lock/var/lib/dpkg/lock-open (11: Resource temporarily unavailable)Unable to lock the management directory (/var/lib/dpkg/), is there any other proce

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

This article mainly introduces the MySQL row-level lock, table-level lock, page-level lock detailed introduction, while enumerating some examples, the need for friends can refer to the following Page level: Engine BDB. Table level: Engine MyISAM, understood to lock the entire table, can read at the same time, wri

Label:This article mainly introduces the MySQL row-level lock, table-level lock, page-level lock detailed introduction, while enumerating some examples, the need for friends can refer to the following Page level: Engine BDB.Table level: Engine MyISAM, understood to lock the entire table, can read at the same time, wri

Tags: lock src proc nbsp BSP log own. com sqlOne, table-level lock 1. Read lock,lock table t_student Read, add read lock, so that other Sessiona and sessionb can not modify the data, just read the data. Show processlist; View process, modify the state is waiting for the tab

It is well known that synchronized can be used to modify methods and blocks of code for classes or objects.When a code block is decorated, synchronized (object) acts on the object, constraining only that object.Synchronized (class) acts on a class, constraining all objects of the class.When modifying a method, the synchronized modifies the static method for the class. Used for objects when modifying non-static methods.Note Class and object locks are two different locks, and they do not have a sy

Pessimistic lock (Pessimistic Lock), as the name implies, is very pessimistic, every time to take the data when they think others will change, so every time when the data are locked, so that other people want to take this data will block until it gets the lock. Traditional relational database in the use of a lot of this locking mechanism, such as row locks, table

The following articles detail the distribution of update locks and exclusive locks during the update operation. Http://blog.csdn.net/zjcxc/article/details/27351779 According to the tracing method described in the above article, we found that in the article lock (2) -- in the process of creating and updating tables, we use sys. the results of the dm_tran_locks dynamic view are the final locking results, but the changes in the locks are not reflected.

Tags: key data Purpose value result bidirectional collation coexistence priorityA lock is a mechanism by which a computer coordinates multiple processes or a purely thread concurrently accessing a resource. in a database, data is a resource that is shared by many users in addition to the contention of traditional computing resources (CPU, RAM, I/O). How to guarantee the consistency and validity of data concurrent access is one of the problems that the