adding chapter 7 source code

Chapter7/multiprocessing/process4.py

@@ -0,0 +1,29 @@
+# process4.py to use shared memory using the server process
+
+import multiprocessing
+from multiprocessing import Process
+
+def insert_data (dict1, code, subject):
+    dict1[code] =  subject
+
+def output(dict1):
+    print("Dictionary data: ", dict1)
+
+with multiprocessing.Manager() as mgr:
+    # create a dictionary in the server process
+    mydict = mgr.dict({100: "Maths", 200: "Science"})
+
+    p1 = Process(target=insert_data, args=(mydict, 300, "English"))
+    p2 = Process(target=insert_data, args=(mydict, 400, "French"))
+    p3 = Process(target=output, args=(mydict,))
+
+    p1.start()
+    p2.start()
+
+    p1.join()
+    p2.join()
+
+    p3.start()
+    p3.join()
+
+print("Exiting the main process")