The code below is an example on multi-threading that the prof presented in class. I am new to coding (first course). I have read on multi-threading and using locks. Reading the theory is fun. var fun = Theory.Read(multi-threading); Actually coding threads and locks seems to baffle me.
Trying to understand how the two threads in the code below will behave. From testing the code it looks like lock1 will not release and message2 is not enqueue-ed, but I might be wrong. Looks like there is a synchronization issue. Is this an example of a deadlock?
I am also wondering why locks and threads are required if two different queues are used. I am not seeing a shared resource.
Is there a way to fix this code to prevent the synchronization issue?
private static object Lock1 = new object(); // Protect MessageQueueOne
private static object Lock2 = new object(); // Protect MessageQueueTwo
private static Queue<string> MessageQueueOne = new Queue<string>();
private static Queue<string> MessageQueueTwo = new Queue<string>();
private static void AddMessages(string message1, string message2)
{
lock (Lock1)
{
// (1) Thread 1 is here...
MessageQueueOne.Enqueue(message1);
lock (Lock2)
{
MessageQueueTwo.Enqueue(message2);
}
}
}
private static void RemoveMessages()
{
lock (Lock2)
{
if (MessageQueueTwo.Count > 0)
{
// (2) Thread 2 is here...
Console.WriteLine(MessageQueueTwo.Dequeue());
}
lock (Lock1)
{
if (MessageQueueOne.Count > 0)
{
Console.WriteLine(MessageQueueOne.Dequeue());
}
}
}
}
private static void Main()
{
Task taskOne = Task.Run(() =>
{
for (int i = 0; i < 100; ++i)
{
AddMessages($"Message One: {DateTime.Now}", $"Message Two: {DateTime.UtcNow}");
Thread.Sleep(25);
}
});
Task taskTwo = Task.Run(() =>
{
for (int i = 0; i < 100; ++i)
{
RemoveMessages();
Thread.Sleep(25);
}
});
taskOne.Wait();
taskTwo.Wait();
Console.Write("Tasks are finished");
Console.ReadKey();
}
