lock computer

Tags: nod tom research htm attribute reference serial environment controlRefer to http://www.jb51.net/article/50047.htm "MySQL row level lock, table level lock, page level lock Details" Page level: Engine BDB.Table level: Engine MyISAM, understood to lock the entire table, can read at the same time, write NoRow level:

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

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

Synchronization control is an essential means of concurrent programs, the Synchronized keyword is a simple control method, in addition, the JDK inside and the package also provides a lock interface, the interface provides the lock () method and Unlock () Method supports explicit and explicit lock-out operations. Reentrantlock (re-entry

Lock synchronization lock -- thread synchronization, Lock synchronization -- threadLock-synchronization Lock Lock is a powerful thread synchronization mechanism provided by Java 5-achieve synchronization by displaying and defining synchronization

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

the memory barrier, read-write spin lock and sequential lock of the lock mechanism in Linux kernelIn the previous blog post, I discussed the related content of atomic manipulation and spin locks, and this post will continue the discussion of locking mechanisms, including memory barriers, read and write spin locks, and sequential

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

Another lock lock is provided after the JDK1.5. Lockimplementations provide a wider synchronized range of locking operations than can be obtained using methods and statements. This implementation allows for a more flexible structure that can have very different properties and can support multiple related Condition objects.A lock is a tool that controls the access

performance cannot linearly increase by 3 CLH because the latency of accessing far-memory far exceeds the local memory. CLH (Craig, Landin, and Hagersten locks): A spin lock that ensures no starvation, provides first-come-first-served fairness. The CLH lock is also a scalable, high-performance, fair spin lock based on the list, and the application thread spins

Hibernate lock mechanism. Let's make a summary today. Hibernate locks include pessimistic locks and optimistic locks. 1. pessimistic lock It refers to a conservative attitude towards data being modified by the outside world. Assume that another customer may be able to access the same data at any time. To maintain the consistency of data operations, the data is locked at the database level, it depends on the

Oracle lock 4: system lock, oracle lock 4 System Oracle databases use multiple system locks to protect internal databases and memory structures. These mechanisms are transparent to users.Latches) Latches are simple and low-level serialization mechanisms that coordinate multiple users to use shared data structures, objects, and files. latches protect shared memory

Oracle lock 3: DDL lock, oracle lock 3ddlWhen an ongoing DDL operation is executed or a schema object (Note) is referenced, the Data dcictionary (DDL) Lock is used to protect the definition of the schema object, only a single schema object is locked during DDL operation. The database never locks the entire data diction

There are two types of file locks: shared and exclusive, that is, read lock (LOCK_SH) and write lock (LOCK_EX) File locks are typically used in this way: $fp = fopen ("filename", "a"); Flock ($FP, lock_sh) or Die ("LOCK error") $str = Fread ($fp, 1024x768); Flock ($FP, lock_un); Fclose ($FP); Note that after fwrite, the file is updated immediately, inste