binary-semaphore

Making binary semaphore shared between multiple processes(not threads , Process Only) using POSIX in C language

由 こ雲淡風輕ζ 提交于 2019-12-22 10:17:18
问题 i am making binary semaphore shared between multiple processes(not threads , Process Only) using POSIX in C language. if i create binary semaphore using mutex, typedef struct BIN_SEMA { pthread_cond_t cv; /* cond. variable - used to block threads */ pthread_mutex_t mutex; /* mutex variable - used to prevents concurrent access to the variable "flag" */ int flag; /* Semaphore state: 0 = down, 1 = up */ } bin_sema; i will be able to use it amongst the threads only , but i want to share between

I want to readers/writers problem with binary semaphore

由 梦想的初衷 提交于 2019-12-13 10:23:56
问题 I have 5 writers, 20 readers. I want to solve readers/writers problem with binary semaphore. But my code has some problem. There is segmentation fault(core dumped). I think that there is a problem when creating threads. How can I solve the problem? and Is this right code to solve r/w problem? I used my text book's pseudo code. #include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <semaphore.h> sem_t mutex, rw_mutex; int data = 0; int readcount = 0; void *reader(void* i) { int

Error while compiling the code 'double free or corruption (out)' using threads in C? [closed]

由 喜你入骨 提交于 2019-12-13 09:55:19
问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 2 years ago . I'm trying to do a ebola simulation using pthreads. Everything worked just fine up to the semaphor part. I'm getting this error while compiling code: *** Error in `./ebola_serial': double free or corruption (out): 0x00007f49700008c0 *** *** Error in `======= Backtrace: =========

How to sync processes using semaphore

由 对着背影说爱祢 提交于 2019-12-12 03:45:13
问题 let's say I have 3 processes including a parent process I have to execute I program in sequence of P3,P1,P2. Guys please help me how I can start the computation from process P3. I need the out as {0,1,2,3,4,5,.. max} For the reference my code snapshot is :- #define SEM_NAME "//test.mutex" //#define SEM_NAME2 "//test2.mutex" int main(int argc, char const *argv[]) { int max = 0, i =0; sem_t *sem; sem_t *sem2; pid_t pid, pid2; sem = sem_open(SEM_NAME, O_CREAT, O_RDWR, 1); sem_unlink(SEM_NAME);

Avoid taking a long time to finish the 'too much milk' scenario

由 三世轮回 提交于 2019-12-11 08:52:52
问题 The following is a simple solution to the 'too much milk problem' lock mutex; while (1){ lock_acquire(mutex); if (no milk) go and buy milk;//action-1 lock_release(mutex); } The problem is that, action-1 can take a lot of time to accomplish, making any of the processes waiting to acquire the mutex to wait for a long time. One way to avoid this is to have a timer so that the process buying milk will return with or without milk once the timer goes off. As you can see, there are problems with

Making binary semaphore shared between multiple processes(not threads , Process Only) using POSIX in C language

由 会有一股神秘感。 提交于 2019-12-05 20:30:58
i am making binary semaphore shared between multiple processes(not threads , Process Only) using POSIX in C language. if i create binary semaphore using mutex, typedef struct BIN_SEMA { pthread_cond_t cv; /* cond. variable - used to block threads */ pthread_mutex_t mutex; /* mutex variable - used to prevents concurrent access to the variable "flag" */ int flag; /* Semaphore state: 0 = down, 1 = up */ } bin_sema; i will be able to use it amongst the threads only , but i want to share between processes. so my question is, how to make binary semaphore using posix counting semaphores ? It's not

Difference between binary semaphore and mutex

由 对着背影说爱祢 提交于 2019-11-26 01:43:30
问题 Is there any difference between a binary semaphore and mutex or are they essentially the same? 回答1: They are NOT the same thing. They are used for different purposes! While both types of semaphores have a full/empty state and use the same API, their usage is very different. Mutual Exclusion Semaphores Mutual Exclusion semaphores are used to protect shared resources (data structure, file, etc..). A Mutex semaphore is "owned" by the task that takes it. If Task B attempts to semGive a mutex
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