semaphore communication

First, the conceptIn simple terms, the semaphore is a counter that describes the number of resources for a critical resource.The essence of Semaphore is a data operation lock, which does not have the function of data exchange, but realizes interprocess communication by controlling other communication resources (file, e

Use_posix_sem Sem_close (Semid); Sem_unlink (Mysem); #endif return 0; } Copy CodeOperation Result:$./a.outSem_val init=0Sem_val after Post=1Parent running!Parent running!Parent running!Parent running!Parent running!Parent EndChild running!Child running!Child running!Child running!Child running!Child EndProgam finishedAs you can see, the parent process executes before the child process executes 5 times after the post semaphore has been p

Linux Process Communication-semaphore usage-Linux general technology-Linux programming and kernel information. The following is a detailed description. I. Related Knowledge Semaphores: an integer; The number of resource entities that tables can be used by concurrent processes when the value is greater than or equal to 0; Number of processes waiting for using the critical section in the age of less than 0; T

Linux inter-process communication (System V) --- semaphoreSemaphore IPC Principle Semaphore communication mechanism is mainly used to synchronize processes to avoid concurrent access to shared resources. Semaphores can identify the number of available system resources. The simplest semaphores are binary semaphores. This is a conceptual diagram of the Linux

; For GetAll and SetAll command struct seminfo *__buf; for Ipc_info commands};The return value of Sem_ctl success is determined by the command parameter, which returns 1 on failure and sets the errnoSpecial Key Values ipc_private ( key parameter of the Semget function )Semget callers can give them Key parameter to pass a special key value ipc_pricate ( Its value is 0) , so whether or not the semaphore already exists, Semget wi

Ucos Real-time operating system of inter-mission communication there are many kinds, I mainly study the SEM, mutex, queue, messagebox these four kinds. System kernel code, these kinds of tasks between the implementation mechanism of the communication mechanism is similar, next record my knowledge of the core code, for later back to see, but it is regrettable that did not carefully learn the extension code o

SetAll command struct seminfo *__buf; for Ipc_info commands};The return value of Sem_ctl success depends on the command parameter, which returns 1 on failure and sets the errnoSpecial Key Values ipc_private ( key parameter of the Semget function )Semget callers can give them Key the parameters pass a special key value ipc_pricate ( Its value is 0) . This allowsthesemget to create a new semaphore regardless of whether the

Title: Linux Process Communication-use semaphores I. Related KnowledgeSemaphores: an integer;The number of resource entities that tables can be used by concurrent processes when the value is greater than or equal to 0;Number of processes waiting for using the critical section in the age of less than 0;The initial semaphore value used for mutex must be greater than 0;It can only be changed through P and V pr

1. Related ConceptsSemaphore: The essence is a kind of data operation Lock, it does not have the function of data exchanging, but realizes inter-process communication through other communication resources (file, external device), which is an external resource identifier itself. Equivalent to a counter, record the number of resources available within the critical resource, and ensure that resources are avail

Well-known semaphore SemphoreIf the signal is a mechanism for the association of external events and processes, then semaphores are the mechanism of communication between processes and threads. Depending on whether the communication between different processes is supported or a different thread within the same process, the se