add python threading examples and intros for lec 18 spoc discuss

related_info/lab7/semaphore_condition/thr-ex1.py

@@ -0,0 +1,43 @@
+#!/bin/env python
+ # -*- coding: utf-8 -*-
+ #filename: peartest.py
+
+import threading, signal
+
+is_exit = False
+
+def doStress(i, cc):
+    global is_exit
+    idx = i
+    while not is_exit:
+        if (idx < 10000000):
+            print "thread[%d]: idx=%d"%(i, idx)
+            idx = idx + cc
+        else:
+            break
+    if is_exit:
+        print "receive a signal to exit, thread[%d] stop."%i
+    else:
+        print "thread[%d] complete."%i
+
+def handler(signum, frame):
+    global is_exit
+    is_exit = True
+    print "receive a signal %d, is_exit = %d"%(signum, is_exit)
+
+if __name__ == "__main__":
+    signal.signal(signal.SIGINT, handler)
+    signal.signal(signal.SIGTERM, handler)
+    cc = 5
+    threads = []
+    for i in range(cc):
+        t = threading.Thread(target=doStress, args=(i,cc))
+        t.setDaemon(True)
+        threads.append(t)
+        t.start()
+    while 1:
+        alive = False
+        for i in range(cc):
+            alive = alive or threads[i].isAlive()
+        if not alive:
+            break