lasso lock

Optimistic lockAlways think that there is no concurrency problem, every time you go to fetch data, always think that there will be no other threads to modify the data, so it will not be locked, but in the update will be judged that other threads before the data is modified, generally using the version number mechanism or CAS operation implementation.For example:There is a table like this:Update each time the condition is appended with a time condition:Update user_info set password= ' Somelog ' w

We used the Synchronized keyword in front of the thread synchronization problem, and today we look at the thread lock lock provided after Java 5.0.The implementation class of the lock interface provides a more flexible and extensive locking object operation than using the Synchronized keyword, and it is an object-oriented way to

I. Use mutex lock 1. initialize mutex Pthread_mutex_t mutex = pthread_mutex_initializer; // static initialization mutex Int pthread_mutex_init (pthread_mutex_t * mutex, pthread_mutexattr_t * ATTR); // dynamically initialize mutex Int pthread_mutex_destory (pthread_mutex_t * mutex); // cancel a mutex. You cannot copy a mutex variable, but you can copy a pointer to the mutex, in this way, multiple functions or threads can share the mutex for synchroniza

Previous Article: Java thread (6) Lock is the interface under the java. util. Concurrent. Locks package,LockThe implementation providesSynchronizedMore extensive lock operations can be obtained by methods and statements. It can handle thread synchronization problems in a more elegant way. We use Java threads (2) the sample code is as follows: Public class locktest {public static void main (string [] ARGs)

Lock Convoy (lock Guard)[1]lock Convoy is a performance degradation problem caused by the use of locks in a multithreaded concurrency environment. Lock convoy problems can arise when multiple threads of the same priority frequently scramble for the same lock, and in general,

the same time to get I and the self-add operation, and finally print output, so I showed the value of 3, followed by three threads are successively get I and make changes, so the output is 4,5,6. If you want to access the shared resource variable I in a sequential manner, you need to add a lock, then the first thought is to use synchronized to control the lock. Public synchronized void Run () { try{

Performance Comparison In JDK1.5, synchronized is inefficient. Because this is a heavyweight operation, its greatest performance impact is the implementation, suspend the thread and recover the thread of the operation need to go into the kernel state of completion, these operations to the system's concurrency has brought great pressure. By contrast, using the lock object provided by Java, the performance is higher. In the multi-threaded environment,

Lock (Locking)In the process of implementing business logic, it is often necessary to guarantee the exclusivity of data access. such as in the final settlement of the financial systemProcessing, we want to process the data for a cut-off point in time, and we don't want to be in the process of closing(may be a few seconds, or maybe a few hours), and the data will change again. At this point, we need to pass some machineSystem to ensure that this data i

I. Introduction to OPTIMISTIC lockingOptimistic lock is a relative pessimistic lock, but also to avoid the database phantom reading, business processing time too long and other reasons cause data processing error of a mechanism, but optimistic lock will not deliberately use the database itself lock mechanism, but accor

This article mainly introduces TM lock in Oracle, understand that when we access the same table object in the database through SQL statements, if more than one user operates on the same table object, it may result in inconsistent data and data inconsistency, please refer to the consistency and atomicity of database transactions. Oracle solves the problem of data inconsistency in multi-threaded situations, mainly through two kinds of locks, one is pess

Recently, Xiaojing gave skynet a pr. We have discussed this for a long time. It is said that it was because the message dispatching Department of skynet was rewritten to solve another problem, which can improve the CPU usage in some cases. Previously, skynet used the cas-based lock-free structure for message scheduling. However, in essence, the data structure of concurrent queues, whether it is Recently, Xiaojing gave skynet a pr. We have discussed th

Sync lock/Recursive lock/co-1 Sync lockLocks are often used to synchronize access to shared resources, create a lock object for each shared resource, call the Acquire () method to get the lock object when you need to access the resource (if another thread has already acquired the l