initial version

Author: leogregianin

README.md

@@ -1,2 +1,46 @@
 # python-concurrency
-Concurrency in Python
+Concurrency and parallelism in Python
+
+    Concurrency is about dealing with lots of things at once. Parallelism is about doing lots of things at once. 
+-- Rob Pike, co-inventor da linguagem Go - Concurrency is not Parallelism (it's better)
+
+    - Ao preparar vários pratos ao mesmo tempo o cozinheiro está trabalhando de forma concorrente, porque normalmente ele só cuida de um prato por vez, mas vários estão sendo preparados ao mesmo tempo. 
+
+    - Por outro lado, um fogão de 6 bocas permite aquecer 6 panelas em paralelo. 
+
+    - Ou seja, o cozinheiro trabalha em modo concorrente e o fogão em modo paralelo.
+-- [Garoa Hacker Clube](https://garoa.net.br/wiki/Python_Concorrente)
+
+# Install packages
+
+    * requests
+    * asyncio
+    * aiohttp
+
+
+# Benchmarks
+
+Benchmark name                       | (1)        | (2)        | (3)        | (4)
+-------------------------------------|-----------:|-----------:|-----------:|-----------:
+synchronous (sync.py)                | 17.366073  | 17.226306  | 15.457684  | 15.195825  
+thread with 5 workers (thread.py)    |  3.248359  |  2.758202  |  1.843235  |  1.813232
+thread with 50 workers (thread.py)   |  0.625699  |  0.756632  |  0.573231  |  0.587740
+parallelism (multiprocess.py)        |  3.607703  |  3.317795  |  2.845974  |  2.705426 
+asynchronous coroutines (async.py)   |  0.586605  |  0.609510  |  0.571612  |  0.579693
+
+ * Time in seconds
+ * (1) with Python 3.6.5
+ * (2) with Python 3.6.5
+ * (3) with Python 3.8.0
+ * (4) with Python 3.8.0
+
+# References
+
+ * [en] [Coroutines and Tasks - Official Python Docs](https://docs.python.org/3/library/asyncio-task.html)
+ * [en] [threading — Thread-based parallelism - Official Python Docs](https://docs.python.org/3/library/threading.html)
+ * [en] [multiprocessing — Process-based parallelism - Official Python Docs](https://docs.python.org/3/library/multiprocessing.html)
+ * [en] [Speed Up Your Python Program With Concurrency](https://realpython.com/python-concurrency)
+ * [en] [An Intro to Threading in Python](https://realpython.com/intro-to-python-threading)
+ * [en] [Async IO in Python: A Complete Walkthrough](https://realpython.com/async-io-python)
+ * [en] [AsyncIO for the Working Python Developer - Yeray Diaz](https://hackernoon.com/asyncio-for-the-working-python-developer-5c468e6e2e8e)
+ * [pt-br] [AsyncIO - O futuro do Python mudou completamente! - Bruno Rocha](http://brunorocha.org/python/asyncio-o-futuro-do-python-mudou-completamente.html)

async.py

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+import asyncio
+import json
+from time import time
+from aiohttp import ClientSession
+from config import api_key, url_base
+
+
+async def how_is_the_weather(client, city):
+    api_url = (f"{url_base}/weather?q={city}&units=metric&APPID={api_key}")
+
+    async with client.get(api_url) as r:
+        weather = await r.json()
+        return weather.get("main", {}).get("temp", "0.0")
+
+
+async def main(loop):
+    requests = []
+    cities = []
+    with open('cities.json', encoding='utf-8') as cities_json:
+        cities_load = json.load(cities_json)
+    [cities.append(c["name"]) for c in cities_load]
+
+    async with ClientSession() as session:
+        for city in cities:
+            requests.append(how_is_the_weather(session, city))
+        temps = await asyncio.gather(*requests)
+
+        for city, temp in zip(cities, temps):
+            print(f"Current weather in {city} is {temp} ºC")
+
+
+if __name__ == "__main__":
+    loop = asyncio.get_event_loop()
+    initial_time = time()
+    loop.run_until_complete(main(loop))
+    elapsed_time = time() - initial_time
+    print(f"Total Time: {elapsed_time}")

cities.json

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+[
+    {
+      "id": 1,
+      "name": "Cuiabá"
+    }, 
+	{
+      "id": 2,
+      "name": "São Paulo"
+    }, 
+	{
+      "id": 3,
+      "name": "Rio de Janeiro"
+    }, 
+	{
+      "id": 4,
+      "name": "Brasília"
+    }, 
+	{
+      "id": 5,
+      "name": "Buenos Aires"
+    }, 
+	{
+      "id": 6,
+      "name": "Santiago"
+    }, 
+	{
+      "id": 7,
+      "name": "Fairbanks"
+    }, 
+	{
+      "id": 8,
+      "name": "Lima"
+    }, 
+	{
+      "id": 9,
+      "name": "La Paz"
+    }, 
+	{
+      "id": 10,
+      "name": "Dubai"
+    }, 
+	{
+      "id": 11,
+      "name": "Quito"
+    }, 
+	{
+      "id": 12,
+      "name": "Caracas"
+    }, 
+	{
+      "id": 13,
+      "name": "Bogotá"
+    }, 
+	{
+      "id": 14,
+      "name": "Rondonópolis"
+    }, 
+	{
+      "id": 15,
+      "name": "New York"
+    }, 
+	{
+      "id": 16,
+      "name": "Miami"
+    }, 
+	{
+      "id": 17,
+      "name": "Chicago"
+    }, 
+	{
+      "id": 18,
+      "name": "Los Angeles"
+    }, 
+	{
+      "id": 19,
+      "name": "San Diego"
+    }, 
+	{
+      "id": 20,
+      "name": "Las Vegas"
+    }, 
+	{
+      "id": 21,
+      "name": "Toronto"
+    }, 
+	{
+      "id": 22,
+      "name": "Montreal"
+    }, 
+	{
+      "id": 23,
+      "name": "Vancouver"
+    }, 	
+	{
+      "id": 24,
+      "name": "Halifax"
+    }, 
+	{
+      "id": 25,
+      "name": "London"
+    }, 	
+	{
+      "id": 26,
+      "name": "Paris"
+	  },
+	{
+      "id": 27,
+      "name": "Campo Grande"
+    },
+  {
+      "id": 28,
+      "name": "Curitiba"
+    },
+  {
+      "id": 29,
+      "name": "Florianópolis"
+    },
+  {
+      "id": 30,
+      "name": "Porto Alegre"
+    }
+]

config.py

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+api_key = "c25ad98fd82f683d09832deb416a71f7"
+url_base = "http://api.openweathermap.org/data/2.5"
+thread_max_workers = 50

multiprocess.py

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+import concurrent.futures
+import requests
+import multiprocessing
+import json
+from time import time
+from config import api_key, url_base
+
+
+session = None
+
+def set_global_session():
+    global session
+    if not session:
+        session = requests.Session()
+
+
+def how_is_the_weather(city):
+    api_url = (f"{url_base}/weather?q={city}&units=metric&APPID={api_key}")
+    
+    with session.get(api_url) as response:
+        weather = response.json()
+        temp = weather.get("main", {}).get("temp", "0.0")
+        print(f"Current weather in {city} is {temp} ºC")
+
+def weather_cities(cities):
+    with multiprocessing.Pool(initializer=set_global_session) as pool:
+        pool.map(how_is_the_weather, cities)
+
+
+if __name__ == "__main__":
+
+    cities = []
+    with open('cities.json', encoding='utf-8') as cities_json:
+        cities_load = json.load(cities_json)
+    [cities.append(c["name"]) for c in cities_load]
+
+    initial_time = time()
+    weather_cities(cities)
+    elapsed_time = time() - initial_time
+    print(f"Total time: {elapsed_time}")

sync.py

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+from time import time
+import requests
+import json
+from config import api_key, url_base
+
+
+def how_is_the_weather(city):
+    api_url = (f"{url_base}/weather?q={city}&units=metric&APPID={api_key}")
+
+    response = requests.get(api_url)
+    weather = response.json()
+    return weather.get("main", {}).get("temp", "0.0")
+
+
+if __name__ == "__main__":
+    initial_time = time()
+
+    cities = []
+    with open('cities.json', encoding='utf-8') as cities_json:
+        cities_load = json.load(cities_json)
+    [cities.append(c["name"]) for c in cities_load]
+
+    for city in cities:
+        temp = how_is_the_weather(city)
+        print(f"Current weather in {city} is {temp} ºC")
+    
+    elapsed_time = time() - initial_time
+    print(f"Total time: {elapsed_time}")

thread.py

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+import concurrent.futures
+import requests
+import threading
+import json
+from time import time
+from config import api_key, url_base, thread_max_workers
+
+
+thread_local = threading.local()
+
+def get_session():
+    if not hasattr(thread_local, "session"):
+        thread_local.session = requests.Session()
+    return thread_local.session
+
+
+def how_is_the_weather(city):
+    session = get_session()
+    api_url = (f"{url_base}/weather?q={city}&units=metric&APPID={api_key}")
+    
+    with session.get(api_url) as response:
+        weather = response.json()
+        temp = weather.get("main", {}).get("temp", "0.0")
+        print(f"Current weather in {city} is {temp} ºC")
+
+
+def weather_cities(cities):
+    with concurrent.futures.ThreadPoolExecutor(max_workers=thread_max_workers) as executor:
+        executor.map(how_is_the_weather, cities)
+
+
+if __name__ == "__main__":
+    initial_time = time()
+
+    cities = []
+    with open('cities.json', encoding='utf-8') as cities_json:
+        cities_load = json.load(cities_json)
+    [cities.append(c["name"]) for c in cities_load]
+
+    weather_cities(cities)
+    elapsed_time = time() - initial_time
+    print(f"Total time: {elapsed_time}")