Adds code for threads.

os/code/os/src/main/java/com/scaler/App.java

@@ -4,10 +4,20 @@ package com.scaler;
  * Hello world!
  *
  */
-public class App 
-{
-    public static void main( String[] args )
-    {
-        System.out.println( "Hello World!" );
+public class App {
+
+    public static void print() {
+        System.out.println("Hello World! printed by: " + Thread.currentThread().getName());
+    }
+
+    public static void main(String[] args) {
+
+        print();
+
+        for (int i = 0; i < 10; i++) {
+            TextPrinter textPrinter = new TextPrinter(String.valueOf(i));
+            Thread thread = new Thread(textPrinter);
+            thread.start();
+        }
     }
 }

os/code/os/src/main/java/com/scaler/TextPrinter.java

@@ -0,0 +1,14 @@
+package com.scaler;
+
+import lombok.AllArgsConstructor;
+
+@AllArgsConstructor
+public class TextPrinter implements Runnable {
+
+    private String text;
+
+    @Override
+    public void run() {
+        System.out.println(text + " printed by: " + Thread.currentThread().getName());
+    }
+}

os/code/os/src/main/java/com/scaler/scheduling/FirstComeFirstServe.java

@@ -10,27 +10,39 @@ import com.scaler.scheduling.models.ScheduledProcess;
 public class FirstComeFirstServe {
 
     public List<ScheduledProcess> schedule(List<IncomingProcess> processes) {
+
+        // Get a sorted list of processes
         Queue<IncomingProcess> queue = prepareQueue(processes);
         List<ScheduledProcess> scheduledProcesses = new LinkedList<>();
 
         int time = 0;
         int index = 0;
+
+        // Check if there are any processes in the queue
         while (!queue.isEmpty()) {
             IncomingProcess process = queue.poll();
+
+            // Increment elapsed time by the burst time of the process
             time += process.getBurstTime();
             index += 1;
 
             process.setCompletedAt(time);
+
+            // Add the process to the list of scheduled processes
             scheduledProcesses.add(new ScheduledProcess(index, process));
         }
 
         return scheduledProcesses;
     }
 
+    // When ever we get a new process, we add it to the queue
     private Queue<IncomingProcess> prepareQueue(List<IncomingProcess> processes) {
+        // Simulate a queue using a linked list
         Queue<IncomingProcess> queue = new LinkedList<>();
 
         List<IncomingProcess> sortedProcesses = new LinkedList<>(processes);
+
+        // Sort the processes by arrival time to simulate FCFS
         sortedProcesses.sort((p1, p2) -> p1.getArrivalTime() - p2.getArrivalTime());
 
         for (IncomingProcess process : sortedProcesses) {

os/code/os/src/main/java/com/scaler/scheduling/models/IncomingProcess.java

@@ -1,8 +1,6 @@
 package com.scaler.scheduling.models;
 
-import lombok.AllArgsConstructor;
 import lombok.Getter;
-import lombok.RequiredArgsConstructor;
 import lombok.Setter;
 
 @Getter