ch21 examples

21-futures/demo_executor_map.py

@@ -0,0 +1,31 @@
+"""
+Experiment with ``ThreadPoolExecutor.map``
+"""
+# tag::EXECUTOR_MAP[]
+from time import sleep, strftime
+from concurrent import futures
+
+def display(*args):  # <1>
+    print(strftime('[%H:%M:%S]'), end=' ')
+    print(*args)
+
+def loiter(n):  # <2>
+    msg = '{}loiter({}): doing nothing for {}s...'
+    display(msg.format('\t'*n, n, n))
+    sleep(n)
+    msg = '{}loiter({}): done.'
+    display(msg.format('\t'*n, n))
+    return n * 10  # <3>
+
+def main():
+    display('Script starting.')
+    executor = futures.ThreadPoolExecutor(max_workers=3)  # <4>
+    results = executor.map(loiter, range(5))  # <5>
+    display('results:', results)  # <6>
+    display('Waiting for individual results:')
+    for i, result in enumerate(results):  # <7>
+        display('result {}: {}'.format(i, result))
+
+if __name__ == '__main__':
+    main()
+# end::EXECUTOR_MAP[]