update from Atlas

futures/countries/flags_threadpool.py

@@ -0,0 +1,42 @@
+"""Download flags of top 20 countries by population
+
+ThreadPool version
+
+Sample run::
+
+    $ python3 flags_threadpool.py
+    BD retrieved.
+    EG retrieved.
+    CN retrieved.
+    ...
+    PH retrieved.
+    US retrieved.
+    IR retrieved.
+    20 flags downloaded in 0.93s
+
+"""
+
+from concurrent import futures
+
+from flags import save_flag, get_flag, main
+
+MAX_WORKERS = 100
+
+
+def download_one(cc):
+    image = get_flag(cc)
+    print('{} retrieved.'.format(cc.upper()))
+    save_flag(image, cc.lower() + '.gif')
+    return cc
+
+
+def download_many(cc_list):
+    workers = min(len(cc_list), MAX_WORKERS)
+    with futures.ThreadPoolExecutor(workers) as executor:
+        res = executor.map(download_one, sorted(cc_list))
+
+    return len(list(res))
+
+
+if __name__ == '__main__':
+    main(download_many)