renumbering chapters >= 19

20-futures/getflags/flags_threadpool_futures.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+
+"""Download flags of top 20 countries by population
+
+ThreadPoolExecutor example with ``as_completed``.
+"""
+from concurrent import futures
+
+from flags import main
+from flags_threadpool import download_one
+
+
+# tag::FLAGS_THREADPOOL_AS_COMPLETED[]
+def download_many(cc_list: list[str]) -> int:
+    cc_list = cc_list[:5]  # <1>
+    with futures.ThreadPoolExecutor(max_workers=3) as executor:  # <2>
+        to_do: list[futures.Future] = []
+        for cc in sorted(cc_list):  # <3>
+            future = executor.submit(download_one, cc)  # <4>
+            to_do.append(future)  # <5>
+            print(f'Scheduled for {cc}: {future}')  # <6>
+
+        for count, future in enumerate(futures.as_completed(to_do), 1):  # <7>
+            res: str = future.result()  # <8>
+            print(f'{future} result: {res!r}')  # <9>
+
+    return count
+# end::FLAGS_THREADPOOL_AS_COMPLETED[]
+
+if __name__ == '__main__':
+    main(download_many)