Write the code about Readers-Writer Problem Implementation.1、 A data set is shared among several concurrent processes: Readers – only read the data set; they do not perform any updates. Writers – can both read and write. 2、 Problem – allow multiple readers (at most 8) to read at the same time. Only one single writer can access the shared data at the same time

Here is an implementation of the Readers-Writer problem in Python, using semaphores:

import threading

class ReadersWriterLock:
    def __init__(self):
        self.lock = threading.Lock()
        self.readers_sem = threading.Semaphore(8)
        self.writers_sem = threading.Semaphore(1)
        self.read_count = 0
    
    def acquire_read(self):
        with self.lock:
            self.read_count += 1
            if self.read_count == 1:
                self.writers_sem.acquire()
        self.readers_sem.acquire()
    
    def release_read(self):
        self.readers_sem.release()
        with self.lock:
            self.read_count -= 1
            if self.read_count == 0:
                self.writers_sem.release()
    
    def acquire_write(self):
        self.writers_sem.acquire()
    
    def release_write(self):
        self.writers_sem.release()

This implementation uses two semaphores - one for readers and one for writers. The `readers_sem` semaphore has a maximum count of 8, allowing up to 8 readers to hold the semaphore at the same time. The `writers_sem` semaphore has a maximum count of 1, allowing only one writer to hold the semaphore at a time.

When a reader wants to read the shared data, it first acquires the `readers_sem` semaphore, which allows up to 8 readers to hold it concurrently. It also increments the `read_count` variable, which keeps track of how many readers are currently reading the data. If this is the first reader, the reader also acquires the `writers_sem` semaphore to prevent any writers from accessing the data while it is being read.

When a reader is done reading the data, it releases the `readers_sem` semaphore and decrements the `read_count` variable. If this was the last reader, the reader also releases the `writers_sem` semaphore to allow any waiting writers to access the data.

When a writer wants to write to the shared data, it first acquires the `writers_sem` semaphore, which allows only one writer to hold it at a time. This prevents any other readers or writers from accessing the data while it is being written to.

When the writer is done writing to the data, it releases the `writers_sem` semaphore to allow any waiting readers or writers to access the data.