Working on 14.2.4 Local vs Shared State

chap14.md

@@ -154,6 +154,47 @@ Pro & Con of Blocking and Spinning:
 
 ### 14.2.4 Local vs Shared State
 
+#### Local State
+
+CLR assign each threas its own memory stack so local variables are kept separate
+
+```csharp
+void Go()
+{
+    // Declare and use a local variable 'cycles'
+    for (int cycles = 0; cycles < 5; cycles++ )
+    {
+        Console.Write('?');
+    }
+}
+
+// Create a new thread and call Go() on it
+new Thread(Go).Start();
+
+// Call Go() on main thread
+Go();
+
+```
+
+#### Shared State
+
+Mutliple threads share data if all threads have a common reference to the same object or variable:
+
+e.g. Both threads share a boolean and that boolean is changed.
+```csharp
+bool _done = false;
+
+new Thread(Go).Start();
+Go();
+
+void Go()
+{
+    if (!_done) { _done = true; Console.WriteLine("Done"); } // Executed only once, as it's _done is changed during one of threads' execution
+}
+```
+
+
+
 ### 14.2.5 Locking and Thread Safety
 
 ### 14.2.6 Passing Data to a Thread