gsa locks

Spin locks and mutually exclusive locks are two important concepts in multi-thread programming. They can all be used to lock some shared resources to prevent concurrent questions that affect data consistency. But there are indeed differences between them. What are these differences?1 Theory Theoretically, when a thread tries to obtain a locked mutually exclusive lock, the operation fails and the thread goes

FCNTL has a powerful capability to copy an existing descriptor, get/Set file descriptor tags, get/Set file status tags, get/Set asynchronous I/O ownership, get/set record locks. When multiple users work together to manipulate a file, Linux usually uses the method of locking the file to avoid competing status with shared resources. There are two types of fcntl file locks: Recommended

The locking mechanism used by the MyISAM storage engine is fully implemented by the table-level locking mechanism provided by MySQL. MySQL has two types of table-level locks: Write locks and read locks. For write locks, MySQL uses the following table locking method:* If there is no lock in the table, put a write lock o

Types and Research of Oracle Database locks, oracle Database locks A database is a shared resource used by multiple users. When multiple users access data concurrently, multiple transactions can access the same data simultaneously in the database. If concurrent operations are not controlled, incorrect data may be read and stored, compromising Database Consistency. There are two basic lock types in the data

The pessimistic lock, as its name implies, is very pessimistic. Every time you get the data, you think someone else will modify it. So every time you get the data, you will lock it, in this way, others will block the data until it gets the lock. In traditional relational databases, many of these locks are used, such as row locks, table locks, read

Two File locks in Linux and two file locks in Linux A file lock is a file read/write mechanism that allows only one process to access one file at any specific time. Using this mechanism can make the process of reading and writing a single file more secure. In this article, we will explore different types of File locks in Linux and use the example program to under

Describe the principles and three implementation methods of distributed locks in detail, and describe the principles of locks. Currently, almost all large websites and applications are deployed in a distributed manner. Data Consistency in Distributed scenarios has always been an important topic. The distributed CAP theory tells us that "No distributed system can meet both Consistency, Availability, and Part

Implement distributed locks Based on Redis and distributed locks Based on Redis BackgroundIn many Internet product applications, some scenarios require locking, such as seckilling, global incremental ID, and floor generation. Most solutions are implemented based on databases. Redis adopts the single-process and single-thread mode and uses the queue mode to convert concurrent access to serial access. In addi

Lightweight locks The JDK1.6 appeared. It is not a substitute for a heavyweight lock, which is meant to reduce the performance consumption of traditional heavyweight locks using operating system mutexes without multiple threading competition. Hotspot the Run-time data of the virtual machine Object Header object itself such as: hash (hashcode), GC generational age (generational GC), this part of the data in

lock is used. Multiple locks can be directly processed in parallel based on different imported keys, similar to the row-level locks of Innodb. Use: $ Lock = new CacheLock ('key _ name '); $ Lock-> lock (); // Logic here $ Lock-> unlock (); // Note that the write permission is required for the path of the file lock. The specific classes are as follows: The code is as follows: /** * CacheLock process loc

Oracle row-level locks and table-level locks. If the row record has been locked, wait for 5 seconds for updates. If the row record is unlocked within these 5 seconds, the query result is returned, if 5 seconds Oracle row-level locks and table-level locks. If the row record has been locked, wait for 5 seconds for update

There is a lock mechanism in Mysql. It is generally used in multi-user concurrent operations. pessimistic locks can prevent the loss of updates and non-repeated read concurrency problems, but they will affect the concurrency performance. So I 'd like to know if Mysql's pessimistic lock will be used in the project program. Thank you for your reference... There is a lock mechanism in Mysql. It is generally used in multi-user concurrent operations. p

Java. util. concurrent. locks. ReentrantLock class usage, concurrent. locksThe lock class is implemented as follows: Explanation of the ReentrantLock interface method: The lock () method is used to obtain the lock object. If the lock is not obtained, the lock is always obtained. Trylock (): A boolean value. It indicates whether the lock is obtained. If the lock is not obtained, false is returned. If the lock is obtained, true is returned. TryLock (lon

Shared lock (s lock ): If transaction t adds a shared lock to data a, other transactions can only add a shared lock to data a and cannot apply exclusive locks. Transactions authorized to share locks can only read data and cannot modify data. Exclusive lock (x lock ): If transaction t adds an exclusive lock to data a, other transactions cannot block aplus any type. Transactions authorized to exclusive

times within a transaction. When this transaction is not finished, another transaction accesses the same data and commits it. Then, between the two read data in the first transaction, the data that the first transaction two reads may be different because of the modification of the second transaction. This occurs when the data that is read two times within a transaction is not the same and is therefore called non-repeatable read. (Workaround: Add a row of lo