updated concurrency examples

concurrency/spinner_thread.py

@@ -0,0 +1,35 @@
+# spinner_thread.py
+# adapted from spinner_proc.py to use threads
+
+import sys
+import time
+import threading
+
+DELAY = 0.1
+DISPLAY = '|/-\\'
+
+
+def spinner_func(before='', after=''):
+    write, flush = sys.stdout.write, sys.stdout.flush
+    while True:
+        for char in DISPLAY:
+            msg = '{} {} {}'.format(before, char, after)
+            write(msg)
+            flush()
+            write('\x08' * len(msg))
+            time.sleep(DELAY)
+
+
+def long_computation():
+    # emulate a long computation
+    time.sleep(3)
+
+
+if __name__ == '__main__':
+    spinner = threading.Thread(
+        None, spinner_func, args=('Please wait...', 'thinking!'))
+    spinner.daemon = True
+    spinner.start()
+
+    long_computation()
+    print('\nComputation done')