M1. Многопоточное программирование

using System;
using System.Threading;

namespace ParallelWork;

class Program
{
    static readonly object locker = new();
    static int sharedData;
    static int readerCount;
    static bool writerActive;

    static void Main()
    {
        for (var i = 0; i < 3; i++)
        {
            var readerThread = new Thread(Reader);
            readerThread.Start();
        }

        for (var i = 0; i < 2; i++)
        {
            var writerThread = new Thread(Writer);
            writerThread.Start();
        }
    }

    private static void Reader()
    {
        while (true)
        {
            lock (locker)
            {
                if (writerActive) Monitor.Wait(locker);

                readerCount++;
                Thread.Sleep(2000);
                Console.WriteLine("ReaderThread {0} считал данные: {1}", Thread.CurrentThread.ManagedThreadId, sharedData);
                readerCount--;

                Monitor.PulseAll(locker);
            }
        }
    }

    private static void Writer()
    {
        while (true)
        {
            lock (locker)
            {
                if (writerActive || readerCount > 0)
                    Monitor.Wait(locker);

                writerActive = true;
                sharedData++;
                Thread.Sleep(1000);
                Console.WriteLine("WriterThread {0} записал данные: {1}", Thread.CurrentThread.ManagedThreadId, sharedData);
                writerActive = false;

                Monitor.PulseAll(locker);
            }
        }
    }
}