![]() T6 = threading.Thread(target = self. Readers are allowed to access the resource simultaneously, while writers must have exclusive access to the resource to avoid data inconsistency. T4 = threading.Thread(target = self.reader) In the reader-writer problem, reader processes only need to read from the shared resource, while writer processes need to write to it. T3 = threading.Thread(target = self.reader) T2 = threading.Thread(target = self.writer) T1 = threading.Thread(target = self.reader) () # Since the write operation is performed, the writer thread is exiting the critical section, hence, we signal wrt making it available for some other writer to enter. Hence, we wait on wrt, blocking other writers from entering. () # At a given point of time there must be only one writer in the critical section. If self.r_c = 0: # If the reader exiting is the last remaining reader, we signal wrt thus allowing writer threads to enter. Self.r_c-=1 # A reader is leaving the critical section hence, decrementing the r_c by 1. If r_c is not equal to 1, it means that the reader thread which arrived earlier did the job of blocking writers from the critical section. If self.r_c = 1: # If the current reader is the first one, we wait on wrt. Self.r_c+=1 # A new reader has entered, hence r_c is incremented by 1. () # Beginning of security region.(Security region needed so that multiple processes are not allowed to update r_c at the same time). # Reader-Writer Problem: import threading Print('Consumer consumes ',em_list)īuf_size=int(input('Enter the buffer size : '))Ĭhoice=int(input('\n1. # Producer Consumer Problem: class ProducerConsumer: ![]() This is python code for 'Producer-consumer/Reader-writer using Semaphore' assignment of This can be implemented using semaphores. However, multiple readers can access the object at the same time. When a writer is accessing the object, no reader or writer may access it. To solve this situation, a writer should get exclusive access to an object. However, if two writers or a reader and writer access the object at the same time, there may be problems. For example, if two readers access the object at the same time there is no problem. ![]() The readers-writers problem is used to manage synchronization so that there are no problems with the object data. they only want to read the data from the object and some of the processes are writers i.e. ![]() The readers-writers problem relates to an object such as a file that is shared between multiple processes. Thus, full slots are 0Įmpty = n // All slots are empty initially “Full” keeps track of the number of items in the buffer at any given time and “Empty” keeps track of the number of unoccupied slots.įull = 0 // Initially, all slots are empty. To solve this problem, we need two counting semaphores – Full and Empty. The critical section cannot be executed by more than one process at the same time.) (Critical Section is the part of a program which tries to access shared resources. In this problem, the buffer is the critical section. We need to ensure that when a producer is placing an item in the buffer, then at the same time consumer should not consume any item. A consumer can pick items and can consume them. A producer can produce an item and can place in the buffer. Operating System and System Software - Computer Engineering of 4.This is 'Producer-consumer/Reader-writer using Semaphore' assignment of Striking the right balance between concurrency and fairness ensures efficient utilization of resources while maintaining equitable access for all threads, promoting a stable and responsive system. While maximizing concurrency is desirable to improve system throughput, it should not come at the expense of fairness, as it may lead to unfair starvation or delay of certain threads. Fairness prevents starvation and ensures that threads are not unfairly delayed or blocked indefinitely. By enabling concurrent access, solutions can handle a higher volume of readers and reduce potential bottlenecks.įairness, on the other hand, ensures that both readers and writers have fair opportunities to access the shared resource. Concurrency ensures that multiple threads can access the shared resource simultaneously, maximizing system throughput and responsiveness. Readers, only read the shared value, no updates. Each reader must access a shared counter value 2000000 times in the critical section. The maximum number of readers allowed is 12 readers. You will accept the number of readers from the command line. Concurrency and fairness are crucial aspects when considering solutions to the readers-writers problem. In C please Implement a solution via semaphores and threads to the n reader 1 writer problem.
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