DiningPhilosopher exercise is modified

ConcurrentCSharp/Asynchronous/Program.cs

@@ -54,7 +54,7 @@ static void ExampleTasks()
         }
         static void Main(string[] args)
         {
-            //Program.ExampleTasks();
+            Program.ExampleTasks();
         }
     }
 }

ConcurrentCSharp/Asynchronous/TaskExamples.cs

@@ -97,11 +97,15 @@ class ConcurrentTasks
         public async Task<int> InvokeAnInefficientAsyncTask()
         {
             int c = 0;
-            Task printTask = new Task(() => Operations.PrintConsole(iterations, wait_time));
+
+            Task printTask = new Task(() => Operations.PrintConsole(iterations, wait_time)); // io bound 
             Console.WriteLine(" Now an Async task is going to be called ...");
             printTask.Start();
+
             await printTask;
-            c = Operations.FindPrimes(min_prime, max_parime);
+
+            c = Operations.FindPrimes(min_prime, max_parime);  // mostly CPU bound task 
+
             Console.WriteLine(" All the tasks are ready here ...");
             return c;
         }
@@ -112,8 +116,11 @@ public async Task<int> InvokeAnEfficientAsyncTask()
             Task printTask = new Task(()=>Operations.PrintConsole(iterations,wait_time));
             Console.WriteLine(" Now an Async task is going to be called ...");
             printTask.Start();
+
             c = Operations.FindPrimes(min_prime, max_parime);
+
             // check: what will be the result if we do not await for printTask? Comment this line and check the output.
+
             await printTask;
             Console.WriteLine(" All the tasks are ready here ...");
             return c;

ConcurrentCSharp/DiningPhilosophers/Program.cs

@@ -11,12 +11,14 @@ static void Main(string[] args)
             int numPhilosphers = 5 , iteration = 300;
             Table table = new Table(numPhilosphers);
 
-            //Console.WriteLine("[Dinining Philospher] Dining with one fork is going to start ...");
+            Console.WriteLine("[Dinining Philospher] Dining with one fork is going to start ...");
             table.startOneForkDining(iteration);
 
             //Console.WriteLine("[Dinining Philospher] Dining with two forks is going to start (press enter)...");
             //Console.ReadLine();
-            //table.startTwoForksDining(iteration);
+            //table.startTwoForksDining(iteration);
+            //table.startTwoForksDiningSafe(iteration);
+
         }
     }
 }

ConcurrentCSharp/DiningPhilosophers/Solution.cs

@@ -86,10 +86,10 @@ public virtual void eatWithTwoForks()
         // solution: no deadlock here, implemented using mutex with timeout
         public void eatWithTwoForksSafe()
         {
-            Int32 timeout = 10;
+            Int32 timeout = 10; // todo: pass timeout as a parameter to the mutexes and check if deadlock happens
             Console.WriteLine("[{0} waiting for right fork ...]", number);
 
-            if (rightFork.forkMutex.WaitOne())
+            if (rightFork.forkMutex.WaitOne())  
             {
                 rightFork.pick();
 
@@ -107,7 +107,7 @@ public void eatWithTwoForksSafe()
             }
         }
 
-        public void startEatingWithOneFork(Object it)
+        public void startEatingWithOneFork(Object it) // why the parameter has the type Object?
         {
             int iterations = (int)it;
             for (int i = 0; i < iterations; i++)
@@ -169,7 +169,9 @@ public void startTwoForksDining(int it)
                 threads[i] = new Thread(philosophers[i].startEatingWithTwoForks);
 
             for (int i = 0; i < threads.Length; i++)
+            {
                 threads[i].Start(it);
+            }
 
             for (int i = 0; i < threads.Length; i++)
                 threads[i].Join();

ConcurrentCSharp/Exercises.md

@@ -294,6 +294,7 @@ Make your solutions ready.
 ## Exercises:
 
 1. [~ 20 min] **DiningPhilosophers**: Check the provided solution.
+   1. In the solution a method (named *startEatingWithTwoForksSafe*) is added to prevent a deadlock. In this method, shared resources are protected using class *Mutex*. Check how instances of this class is used. First, try the code without timeout. You should see the deadlock. Then, pass timeout as a parameter to the methods *WaitOne*. Do you expect a deadlock? Justify your answer.
 2. [~ 30 min] **Semaphores**: We have learned how producers consumers can be synchronized with semaphores. 
    1. Check the provided solution.
    2. Wtach this video to see how semaphores can be initialized to exploit full capacity of a shared buffer.

ConcurrentCSharp/MergeSort/Program.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Threading;
 using Exercise;
-//using Solution;
+using Solution;
 
 namespace Program
 {
@@ -15,14 +15,14 @@ static void Main(string[] args)
 
             SequentialMergeSort mergeSort = new SequentialMergeSort(arr);
 
-            mergeSort.printContent("\n Before the sequential merge-sort ");
+            mergeSort.printContent("\n Before the sequential merge-sort \n");
             mergeSort.sortSeq(0, arr.Length - 1);
-            mergeSort.printContent("\n After the sequential merge-sort ");
+            mergeSort.printContent("\n After the sequential merge-sort \n");
 
             // uncomment this only if the solution is available
-            //Console.WriteLine("\n Now concurrent sort will be running ...");
-            //SolutionConcurrentMergeSort concMergeSort = new SolutionConcurrentMergeSort();
-            //concMergeSort.sortCon(arr);
+            Console.WriteLine("\n Now concurrent sort will be running ...\n");
+            SolutionConcurrentMergeSort concMergeSort = new SolutionConcurrentMergeSort();
+            concMergeSort.sortCon(arr);
 
         }
     }

ConcurrentCSharp/PrimeNumbers/Exercise.cs

@@ -41,6 +41,7 @@ public void runSequential(int m, int M)
             sw.Start();
             PrimeNumbers.printPrimes(m, M);
             sw.Stop();
+
             Console.WriteLine("Time for sequential version is {0} msec,", sw.ElapsedMilliseconds);
         }
     }

ConcurrentCSharp/PrimeNumbers/Program.cs

@@ -2,8 +2,8 @@
 using System.Diagnostics;
 using System.Threading;
 using Exercise;
-using Concurrent;
-//using Solution;
+//using Concurrent;
+using Solution;
 
 /// <summary>
 /// This example implements a concurrent version of finding and printing prime-numbers between two given numbers.
@@ -20,7 +20,9 @@ static void Main(string[] args)
             ConPrimeNumbers pn = new ConPrimeNumbers();
 
             pn.runSequential(min, max);
-            Thread.Sleep(2000);
+
+            Thread.Sleep(5000);
+
             pn.runConcurrent(min, max);
 
 

ConcurrentCSharp/PrimeNumbers/Solution.cs

@@ -19,9 +19,9 @@ public class ConPrimeNumbers: PrimeNumbers
         /// <param name="nt"> is the number of threads. For simplicity assume two.</param>
         public void runConcurrent(int m, int M)
         {
-            int nt = 2;
+            int nt = 2; // number of devisions
 
-            // Todo 1: Create nt number of threads, define their segments and start them. Join them all to have all the work done.
+            // Create nt number of threads, define their segments and start them. Join them all to have all the work done.
             Stopwatch sw = new Stopwatch();
 
             int numTs = nt;
@@ -44,7 +44,9 @@ public void runConcurrent(int m, int M)
             sw.Start();
             for (int i = 0; i < numTs; i++)
                 ts[i].Start();
+
             // Here, the main thread can be busy with something else
+
             for (int i = 0; i < numTs; i++)
                 ts[i].Join();
 

ConcurrentCSharp/ProcessCreation/Program.cs

@@ -1,5 +1,5 @@
 using Exercise;
-//using Solution;
+using Solution;
 
 namespace Program
 {
@@ -9,7 +9,7 @@ static void Main(string[] args)
         {
             new ProcessCreation().createProcess();
             //uncomment this only when Solution is available
-            //new SolutionProcessCreation().createProcess();
+            new SolutionProcessCreation().createProcess();
         }
     }
 }

ConcurrentCSharp/ProcessCreation/Solution.cs

@@ -11,8 +11,8 @@ public override void createProcess()
         {
             // First define your process
             ProcessStartInfo prInfo = new ProcessStartInfo();
-            prInfo.FileName = "dotnet"; // This is an executable program.
-            prInfo.Arguments = "../../../../Processes/bin/Debug/netcoreapp3.1/Processes.dll";
+            prInfo.FileName = "ls"; // This is an executable program.
+            prInfo.Arguments = "-all";
             prInfo.CreateNoWindow = false; // This means start the process in a new window
             prInfo.UseShellExecute = false;