add python threading examples and intros for lec 18 spoc discuss

related_info/lab7/semaphore_condition/thr-ex5.py

@@ -0,0 +1,53 @@
+#coding=utf-8
+#!/usr/bin/env python
+  
+import threading  
+import time  
+   
+condition = threading.Condition()  
+products = 0  
+   
+class Producer(threading.Thread):  
+    def __init__(self):  
+        threading.Thread.__init__(self)  
+          
+    def run(self):  
+        global condition, products  
+        while True:  
+            if condition.acquire():  
+                if products < 10:  
+                    products += 1;  
+                    print "Producer(%s):deliver one, now products:%s" %(self.name, products)  
+                    condition.notify()  
+                else:  
+                    print "Producer(%s):already 10, stop deliver, now products:%s" %(self.name, products)  
+                    condition.wait();  
+                condition.release()  
+                time.sleep(2)  
+          
+class Consumer(threading.Thread):  
+    def __init__(self):  
+        threading.Thread.__init__(self)  
+          
+    def run(self):  
+        global condition, products  
+        while True:  
+            if condition.acquire():  
+                if products > 1:  
+                    products -= 1  
+                    print "Consumer(%s):consume one, now products:%s" %(self.name, products)  
+                    condition.notify()  
+                else:  
+                    print "Consumer(%s):only 1, stop consume, products:%s" %(self.name, products)  
+                    condition.wait();  
+                condition.release()  
+                time.sleep(2)  
+                  
+if __name__ == "__main__":  
+    for p in range(0, 2):  
+        p = Producer()  
+        p.start()  
+          
+    for c in range(0, 10):  
+        c = Consumer()  
+        c.start()