semaphore communication

Python lock, semaphore, event for thread synchronization, pythonsemaphore The lock mechanism is a common thread synchronization mechanism for java, C #, and python. Compared with the lock mechanism for C #, python locks are relatively simple, you can directly call the lock of the threading standard library. the lock class of python has two functions: the acquire function and the release function. The former serves as the lock function and sets the sta

Mutex is a key. When a person takes the key, they can enter a room. When they come out, the key is handed over to the first in the queue. Generally, this method is used to serialize the access to the critical section code to ensure that the Code is not run in parallel. Semaphore is a room that can accommodate n people. If not, you can enter the room. If the person is full, you have to wait for someone to come out. For n = 1, it is called binary

between processes is small, for example, by exchanging only one state information, but in many cases there is a need to exchange large amounts of data between processes, for example, to send a batch of messages or an entire file, which can be accomplished through a new communication mechanism, The work of exchanging information between processes is called process communication IPC (interprocess

space.void *shmat (int shmid, void *addr, int flag);Shmid the shared storage identifier returned for the Shmget function, the addr and flag parameters determine how the address of the connection is determined, the return value of the function is the actual address to which the process data segment is connected, and the process can read and write to the process.The point of note for interprocess communication using shared storage is to synchronize dat

() Results: 3) Event The event contains a flag bit that is false at the initial time.You can use Set () to set it to true;or use Clear () to reset it to false;You can use Is_set () to check the status of the flag bit;Another most important function is wait (timeout=none), which blocks the current thread until the internal flag bit of the event is set to TRUE or the timeout timeout. If the internal flag bit is true, the wait () function understands the return. Instance: (

Transferred from: http://blog.csdn.net/goodluckwhh/article/details/9006065Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.Directory (?) [-] A signal volume The concept of signal volume Semaphore data structures and related APIs Data Initialization Acquiring and releasing semaphores The concept of Read and write semaphores Data str

A mutex is a key that a person takes to enter a room and gives the key to the first one in the queue when it comes out. The general usage is to serialize access to the critical section code to ensure that the code is not run in parallel.Semaphore is a room that can accommodate n people, if people are dissatisfied can go in, if people full, it is necessary to wait for someone to come out. In the case of N=1, it is called binary semaphore. The general u

operation is a low-level communication of processes.The data structure of semaphore is a value and a pointer. The Pointer Points to the next process waiting for the semaphore. The semaphore value is related to the usage of the corresponding resource. When its value is greater than 0, it indicates the number of current

ObjectiveIn a multithreaded environment, the JDK provides developers with a number of components for user use (mainly under java.util.concurrent), so that users do not need to be concerned about how to write code that takes into account both thread safety and efficiency in a specific scenario. Before the thread pool, Blockingqueue are under the Java.util.concurrent component, although the timer is not under the java.util.concurrent, but it is also considered. The latter two articles will briefly

This article mainly introduces Python multi-process synchronization Lock, Semaphore, and Event instances. Lock is used to avoid access conflicts, Semaphore is used to control the number of accesses to shared resources, and Event is used to implement synchronous communication between processes, for more information, see the synchronization method. 1) Lock When mu

Ucos events are divided into clocks, semaphores, mutex semaphores, message queues, and message mailboxesFirst, the signal volume.The type of semaphore in Ucos is defined as Os_event_type_sem, in the task control block ECB, the semaphore counter oseventcnt is used mainly, when there is a task request semaphore, if the semaphor