Concurrency with Gevent

Presented last October 2013 meetup of Pizzapy (http://pizzapy.ph/)

Transcript

1. Concurrency with Gevent
   Marconi Moreto
   @marconimjr
   

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2. Concurrency
   From Wikipedia:
   “... concurrency is a property of systems in which
   several computations are executing simultaneously,
   and potentially interacting with each other”
   Gevent
   “gevent is a coroutine-based Python networking
   library that uses greenlet to provide a high-level
   synchronous API on top of the libevent event loop”
   From http://www.gevent.org
   

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3. Concurrency is not
   Parallelism
   “Concurrency is not parallelism, although it enables
   parallelism. If you have only one processor, your
   program can still be concurrent but it cannot be
   parallel.”
   - Rob Pike
   

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4. Lets see some code
   Stand back, I know concurrency
   

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5. import time
   import random
   def worker(multiplier):
   time.sleep(random.random())
   print '*' * multiplier
   for i in range(1, 6):
   worker(i)
   Synchronous
   

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6. import time
   import random
   def worker(multiplier):
   time.sleep(random.random())
   print '*' * multiplier
   for i in range(1, 6):
   worker(i)
   Synchronous
   *
   **
   ***
   ****
   *****
   Output:
   

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7. import time
   import random
   def worker(multiplier):
   time.sleep(random.random())
   print '*' * multiplier
   for i in range(1, 6):
   worker(i)
   Synchronous
   *
   **
   ***
   ****
   *****
   Output:
   worker(1)
   worker(2)
   worker(3)
   worker(4)
   worker(5)
   

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8. import time
   import random
   def worker(multiplier):
   time.sleep(random.random())
   print '*' * multiplier
   for i in range(1, 6):
   worker(i)
   Synchronous
   *
   **
   ***
   ****
   *****
   Output:
   worker(1)
   worker(2)
   worker(3)
   worker(4)
   worker(5)
   Start
   Stop
   

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9. import time
   import random
   def worker(multiplier):
   time.sleep(random.random())
   print '*' * multiplier
   for i in range(1, 6):
   worker(i)
   Synchronous
   *
   **
   ***
   ****
   *****
   Output:
   worker(1)
   worker(2)
   worker(3)
   worker(4)
   worker(5)
   Start
   Stop
   

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10. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    

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11. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    

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12. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    

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13. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    

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14. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    2
    

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15. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    3
    1
    2
    

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16. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    3
    1
    2
    4
    

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17. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    Asynchronous printing workers
    *****
    ****
    *
    **
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    3
    1
    2
    4
    5
    

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18. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    

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19. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    ****
    *
    ***
    Output:
    

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20. import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    ****
    *
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    

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21. 1
    import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    ****
    *
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    

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22. 1
    import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    ****
    *
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    

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23. 1
    import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    ****
    *
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    3
    

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24. 1
    Timeout
    import gevent
    import random
    def worker(multiplier):
    gevent.sleep(random.random())
    print '*' * multiplier
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets, timeout=0.5)
    Workers with timeout
    ****
    *
    ***
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    3
    

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25. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    

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26. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    

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27. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    

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28. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    

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29. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    2
    

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30. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    3
    1
    2
    

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31. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    3
    1
    2
    4
    

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32. import random
    import gevent
    def worker(multiplier):
    gevent.sleep(random.random())
    return '*' * multiplier
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    return [g.value for g in greenlets]
    print '\n'.join(producers())
    Collecting workers result
    *
    **
    ***
    ****
    *****
    Output:
    worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    3
    1
    2
    4
    5
    

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33. import random
    import gevent
    from gevent.queue import Queue
    tasks = Queue()
    def worker(multiplier):
    gevent.sleep(random.random())
    tasks.put('*' * multiplier)
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    def consumer():
    while True:
    print tasks.get()
    gevent.spawn(consumer)
    producers()
    Producers and consumer (1/2)
    

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34. import random
    import gevent
    from gevent.queue import Queue
    tasks = Queue()
    def worker(multiplier):
    gevent.sleep(random.random())
    tasks.put('*' * multiplier)
    def producers():
    greenlets = [gevent.spawn(worker, i)
    for i in range(1, 6)]
    gevent.joinall(greenlets)
    def consumer():
    while True:
    print tasks.get()
    gevent.spawn(consumer)
    producers()
    Producers and consumer (1/2)
    ***
    *
    **
    ****
    *****
    Output:
    

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35. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    Producers and consumer (2/2)
    Queue
    Head
    

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36. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    Producers and consumer (2/2)
    Queue
    Head
    

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37. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    Producers and consumer (2/2)
    Queue
    Head
    

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38. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    Producers and consumer (2/2)
    Queue
    Head
    ***
    

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39. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    Producers and consumer (2/2)
    Queue
    Head
    ***
    

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40. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    

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41. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    

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42. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    

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43. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    

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44. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    

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45. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    

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46. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    

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47. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    

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48. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    

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49. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    

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50. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    ****
    

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51. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    5
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    ****
    

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52. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    5
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    ****
    

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53. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    5
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    ***
    *
    **
    ****
    *****
    

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54. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    5
    4
    3
    1
    Producers and consumer (2/2)
    Queue
    Head Consumer
    

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55. import random
    import gevent
    from gevent.queue import Queue
    from gevent.pool import Pool
    pool = Pool(2)
    tasks = Queue()
    def worker(multiplier):
    gevent.sleep(random.random())
    tasks.put('*' * multiplier)
    def producers():
    pool.map(worker, range(1, 6))
    def consumer():
    while True:
    print tasks.get()
    gevent.spawn(consumer)
    producers()
    Worker pool (1/2)
    

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56. import random
    import gevent
    from gevent.queue import Queue
    from gevent.pool import Pool
    pool = Pool(2)
    tasks = Queue()
    def worker(multiplier):
    gevent.sleep(random.random())
    tasks.put('*' * multiplier)
    def producers():
    pool.map(worker, range(1, 6))
    def consumer():
    while True:
    print tasks.get()
    gevent.spawn(consumer)
    producers()
    Worker pool (1/2)
    **
    *
    ****
    *****
    ***
    Output:
    

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57. Worker pool (2/2)
    Queue
    Head
    

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58. worker(1)
    worker(2)
    Worker pool (2/2)
    Queue
    Head
    

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59. worker(1)
    worker(2)
    1
    Worker pool (2/2)
    Queue
    Head
    

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60. worker(1)
    worker(2)
    1
    Worker pool (2/2)
    Queue
    Head
    

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61. worker(1)
    worker(2)
    1
    Worker pool (2/2)
    **
    Queue
    Head
    

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62. worker(1)
    worker(2)
    1
    Worker pool (2/2)
    **
    Queue
    Head
    

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63. worker(1)
    worker(2)
    1
    Worker pool (2/2)
    **
    Queue
    Head Consumer
    

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64. worker(1)
    worker(2)
    1
    Worker pool (2/2)
    **
    Queue
    Head Consumer
    

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65. worker(1)
    worker(2)
    2
    1
    Worker pool (2/2)
    **
    Queue
    Head Consumer
    

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66. worker(1)
    worker(2)
    2
    1
    Worker pool (2/2)
    **
    Queue
    Head Consumer
    

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67. worker(1)
    worker(2)
    2
    1
    Worker pool (2/2)
    **
    *
    Queue
    Head Consumer
    

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68. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    1
    Worker pool (2/2)
    **
    *
    Queue
    Head Consumer
    

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69. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    3
    1
    Worker pool (2/2)
    **
    *
    Queue
    Head Consumer
    

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70. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    3
    1
    Worker pool (2/2)
    **
    *
    Queue
    Head Consumer
    

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71. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    3
    1
    Worker pool (2/2)
    **
    *
    ****
    Queue
    Head Consumer
    

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72. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Worker pool (2/2)
    **
    *
    ****
    Queue
    Head Consumer
    

    View Slide

73. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Worker pool (2/2)
    **
    *
    ****
    Queue
    Head Consumer
    

    View Slide

74. worker(1)
    worker(2)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Worker pool (2/2)
    **
    *
    ****
    *****
    Queue
    Head Consumer
    

    View Slide

75. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    Worker pool (2/2)
    **
    *
    ****
    *****
    Queue
    Head Consumer
    

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76. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    5
    Worker pool (2/2)
    **
    *
    ****
    *****
    Queue
    Head Consumer
    

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77. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    5
    Worker pool (2/2)
    **
    *
    ****
    *****
    Queue
    Head Consumer
    

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78. worker(1)
    worker(2)
    worker(3)
    worker(4)
    worker(5)
    2
    4
    3
    1
    5
    Worker pool (2/2)
    **
    *
    ****
    *****
    ***
    Queue
    Head Consumer
    

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79. But, but, what about real
    examples?
    

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80. Shorty: URL shortener
    - TCP
    - Message framing
    

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81. Shorty: URL shortener
    Client
    - TCP
    - Message framing
    

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82. Shorty: URL shortener
    Client Server
    - TCP
    - Message framing
    

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83. Shorty: URL shortener
    Client Server
    Long URL:
    Length + Payload
    - TCP
    - Message framing
    

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84. Shorty: URL shortener
    Client Server
    Long URL:
    Length + Payload
    - TCP
    - Message framing
    

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85. Shorty: URL shortener
    Client Server
    Long URL:
    Length + Payload
    Shortened URL:
    Length + Payload
    - TCP
    - Message framing
    

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86. Shorty: URL shortener
    Client Server
    Long URL:
    Length + Payload
    Shortened URL:
    Length + Payload
    - TCP
    - Message framing
    

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87. Shorty: URL shortener
    Client Server
    Long URL:
    Length + Payload
    Shortened URL:
    Length + Payload
    - TCP
    - Message framing
    Print short URL
    

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88. Shorty: URL shortener
    Client Server
    Long URL:
    Length + Payload
    Shortened URL:
    Length + Payload
    Close enough :P
    - TCP
    - Message framing
    Print short URL
    

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89. ...
    server = socket(AF_INET, SOCK_STREAM)
    server.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
    server.bind(('', 9000))
    server.listen(500)
    def handle(conn, addr):
    logger.info('connected to {0}'.format(addr))
    time.sleep(1) # delay
    # read payload
    payload_len_buf = read_bytes(conn, PLEN_BUF_SIZE)
    payload_len = struct.unpack('payload_buf = read_bytes(conn, payload_len)
    # shorten url and send it back
    short_url = shorten(payload_buf)
    payload_len = struct.pack('conn.sendall(payload_len + short_url)
    conn.close()
    # accept and handle incoming client connections
    while True:
    conn, addr = server.accept()
    handle(conn, addr)
    Blocking server
    

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90. Client
    ...
    def run():
    # connect to server
    client = socket()
    client.connect(('', 9000))
    # send payload
    payload = 'http://127.0.0.1:5000/{0}'.format(uuid.uuid4())
    payload_len = struct.pack('client.sendall(payload_len + payload)
    # read payload
    payload_len_buf = read_bytes(client, PLEN_BUF_SIZE)
    payload_len = struct.unpack('payload_buf = read_bytes(client, payload_len)
    client.close()
    return payload_buf
    if __name__ == '__main__':
    print run()
    

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91. Client
    ...
    def run():
    # connect to server
    client = socket()
    client.connect(('', 9000))
    # send payload
    payload = 'http://127.0.0.1:5000/{0}'.format(uuid.uuid4())
    payload_len = struct.pack('client.sendall(payload_len + payload)
    # read payload
    payload_len_buf = read_bytes(client, PLEN_BUF_SIZE)
    payload_len = struct.unpack('payload_buf = read_bytes(client, payload_len)
    client.close()
    return payload_buf
    if __name__ == '__main__':
    print run()
    http://127.0.0.1:5000/867nv
    Output:
    

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92. So how does it perform?
    

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93. ...
    CONCURRENCY = 10
    ...
    class Agent(Thread):
    ...
    if __name__ == '__main__':
    runner = Runner()
    start = time.time()
    for _ in range(CONCURRENCY):
    agent = Agent(runner)
    agent.setDaemon(True)
    agent.start()
    print 'spawned {0} agents'.format(runner.spawned_agents)
    while runner.running_agents > 0:
    time.sleep(1)
    print 'connections/second: {0}'.format(runner.conn_per_sec)
    runner.reset_conn_per_sec()
    end = time.time()
    elapsed = end - start
    print 'took: {0}'.format(elapsed)
    Benchmark against
    blocking server
    

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94. ...
    CONCURRENCY = 10
    ...
    class Agent(Thread):
    ...
    if __name__ == '__main__':
    runner = Runner()
    start = time.time()
    for _ in range(CONCURRENCY):
    agent = Agent(runner)
    agent.setDaemon(True)
    agent.start()
    print 'spawned {0} agents'.format(runner.spawned_agents)
    while runner.running_agents > 0:
    time.sleep(1)
    print 'connections/second: {0}'.format(runner.conn_per_sec)
    runner.reset_conn_per_sec()
    end = time.time()
    elapsed = end - start
    print 'took: {0}'.format(elapsed)
    Benchmark against
    blocking server
    Output:
    ...
    took: 11.0153269768
    

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95. What did we discover?
    - Blocks on each request
    - Very slow
    - Poor performance
    - Isn’t web scale
    

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96. import gevent
    from gevent import monkey; monkey.patch_socket()
    from gevent.pool import Pool
    from gevent.socket import socket
    ...
    ...
    pool = Pool(100)
    server = socket(AF_INET, SOCK_STREAM)
    server.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
    server.bind(('', 9000))
    server.listen(50)
    def handle(conn, addr):
    logger.info('connected to {0}'.format(addr))
    gevent.sleep(1) # delay
    ...
    # accept and handle incoming client connections
    while True:
    conn, addr = server.accept()
    pool.spawn(handle, conn, addr)
    Non-blocking server
    

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97. import gevent
    from gevent import monkey; monkey.patch_socket()
    from gevent.pool import Pool
    from gevent.socket import socket
    ...
    ...
    pool = Pool(100)
    server = socket(AF_INET, SOCK_STREAM)
    server.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
    server.bind(('', 9000))
    server.listen(50)
    def handle(conn, addr):
    logger.info('connected to {0}'.format(addr))
    gevent.sleep(1) # delay
    ...
    # accept and handle incoming client connections
    while True:
    conn, addr = server.accept()
    pool.spawn(handle, conn, addr)
    Non-blocking server
    ...
    took: 2.00628781319
    Output:
    

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98. How about now?
    - Doesn’t block on each request
    - Signi!cantly faster
    - Better performance
    

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99. Links
    Gevent home page:
    http://www.gevent.org/
    Gevent for working python developer:
    http://sdiehl.github.io/gevent-tutorial/
    Multi-part !le downloader using gevent:
    https://github.com/marconi/pullite/tree/experiment
    Slides and source !les:
    https://github.com/pizzapy/oct2013-meetup
    

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100. Thank you
     Marconi Moreto
     @marconimjr
     http://marconijr.com
     https://github.com/marconi
     

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