China
Africa
Explore chapters and articles related to this topic
Parallel Programming Using OpenMP
Published in Subrata Ray, Fortran 2018 with Parallel Programming, 2019
The pair of instruction ensures that only a single thread accesses the enclosed code at any one time. While one thread is executing the code within the critical/end critical directive, if another thread reaches the critical section, it will wait until the current thread executing the critical section finishes its task. This ensures that only one thread can access the critical section at a time. program cri_1 use omp_lib implicit none integer:: sum=0,i!$omp parallel do do i=1,1000!$omp critical sum=sum+i!$omp end critical end do !$omp end parallel do print *, sum end program cri_1
Multithreading in LabVIEW
Published in Rick Bitter, Taqi Mohiuddin, Matt Nawrocki, LabVIEW™ Advanced Programming Techniques, 2017
Rick Bitter, Taqi Mohiuddin, Matt Nawrocki
When writing C/C++ code to be called by LabVIEW, you need to know if it will possibly be called by multiple threads of execution. If so, then you need to include appropriate protection for the code. It is fairly simple to provide complete coverage for small functions. The Include file that is needed in Visual C++ is process.h. This file contains the definitions for Critical Sections, Mutexes, and Semaphores. This example is fairly simple and will use Critical Sections for data protection. A Critical Section is used to prevent multiple threads from running a defined block of code. Internal data items are protected because their access is within these defined blocks of code. Critical Sections are the easiest thread protection mechanism available to the Windows programmer, and their use should be considered first.
Interprocess Communication Primitives in POSIX/Linux
Published in Ivan Cibrario Bertolotti, Gabriele Manduchi, Real-Time Embedded Systems, 2017
Ivan Cibrario Bertolotti, Gabriele Manduchi
Mutex is an abbreviation for “mutual exclusion,” and mutex variables are used for protecting shared data when multiple writes occur by letting at the most one thread at a time execute critical sections of code in which shared data structures are modified. A mutex variable acts like a “lock” protecting access to a shared data resource. Only one thread can lock (or own) a mutex variable at any given time. Thus, even if several threads try to lock a mutex concurrently, only one thread will succeed, and no other thread can own that mutex until the owning thread unlocks it. The operating system will put any thread trying to lock an already locked mutex in wait state, and such threads will be made ready as soon as the mutex is unlocked. If more than one thread is waiting for the same mutex, they will compete for it, and only one will acquire the lock this turn.
Integrated fault-tolerant control of assembly and automated guided vehicle-based transportation layers
Published in International Journal of Computer Integrated Manufacturing, 2022
Pawel Majdzik, Marcin Witczak, Bogdan Lipiec, Zbigniew Banaszak
The mutual exclusion is a property of concurrency control in which only one task, from a set of concurrent tasks, can perform its critical section. The execution of the critical section refers to an interval of time during which a task accesses a shared resource. To explain the representation of the mutual exclusion framework, let us start with the synchronization of inlet conveyor belts realized by the Epson robot (points 1a, 1b and 2 in figure 1). The operation of picking a cube up from two input conveyor belts is to be considered as a critical section. This is due to the fact that at the same time the Epson robot can only operate one of the two cubes. Additionally, as long as the picking up operation is performed, the conveyor belt is stopped. This means that the subsequent cube can be transferred iff the previous one is taken away with the Epson manipulator. Such a relation is treated as a critical operation. This lead to the transformation of conveyor belt operation portrayed in figure 4. It can be observed that the transportation operation pertaining to the first belt can be started immediately after processing operation (with the start time denoted by ) is terminated. This feature is represented by the arcs (weighted by ) among and inlets and , respectively. Consequently, this part of the system can be perceived and analysed as a closed and cyclic one.
Fusion of dedicated and shared storage to maximize the use of space of static warehouses
Published in Journal of Industrial and Production Engineering, 2019
Najlae Alfathi, Abdelouahid Lyhyaoui, Abdelfettah Sedqui
This problem exists in the distributed computing systems under the name of mutual exclusion. The role of this concept is to guarantee the access of several requesters to a common resource. It ensures that at most one requester can access to a shared resource called a critical section (security property). And, that any request for access to the critical section will be satisfied in a finite time (property of vivacity) [16]. Several algorithms have been proposed to manage the access to these critical sections. Such as the algorithm of Tréhel and Naimi [17] which reduces the number of messages to log (n) by introducing a logical tree of request and a token.