add some multiprocess and race condition examples

Concurrence_examples/daemon_example.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+import time
+import sys
+import multiprocessing
+
+
+def daemon():
+    p = multiprocessing.current_process()
+
+    print('Starting: {}, {}'.format(p.name, p.pid))
+    sys.stdout.flush()
+    time.sleep(2)
+    print('Exiting : {}, {}'.format(p.name, p.pid))
+
+    sys.stdout.flush()
+
+
+def non_daemon():
+    p = multiprocessing.current_process()
+
+    print('Starting: {}, {}'.format(p.name, p.pid))
+    sys.stdout.flush()
+    print('Exiting : {}, {}'.format(p.name, p.pid))
+
+    sys.stdout.flush()
+
+
+
+if __name__ == '__main__':
+    d = multiprocessing.Process(name='daemon', target=daemon)
+    d.daemon = True
+
+    n = multiprocessing.Process(name='non-daemon', target=non_daemon)
+    n.daemon = False
+
+    d.start()
+    time.sleep(1)
+    n.start()

Concurrence_examples/logging_example.py

@@ -0,0 +1,15 @@
+#!/usr/bin/env python3
+
+import multiprocessing
+import logging
+import sys
+
+def worker():
+    print 'Doing some work'
+    sys.stdout.flush()
+
+if __name__ == '__main__':
+    multiprocessing.log_to_stderr(logging.DEBUG)
+    p = multiprocessing.Process(target=worker)
+    p.start()
+    p.join()

Concurrence_examples/race_coditions.py

@@ -3,17 +3,16 @@
 import threading
 
 x = 0     
-
 COUNT = 10000000
 
 def foo():
     global x
-    for i in xrange(COUNT):
+    for i in range(COUNT):
         x += 1
 
 def bar():
     global x
-    for i in xrange(COUNT):
+    for i in range(COUNT):
         x -= 1
 
 t1 = threading.Thread(target=foo)

Concurrence_examples/thread_example.py

@@ -8,7 +8,7 @@ import threading
 def worker(n):
     sleep = random.randrange(1, 10)
     time.sleep(sleep)
-    print("Worker {}: sleeping for {} seconds.".format(n, sleep))
+    print("Worker {} from {}: sleeping for {} seconds.".format(n, threading.get_ident(), sleep))
 
 
 for i in range(5):