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Concurrency with Gevent

Concurrency with Gevent

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

Marconi Moreto

October 29, 2013
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  1. Concurrency with Gevent
    Marconi Moreto
    @marconimjr

    View Slide

  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

    View Slide

  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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

  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)

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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:

    View Slide

  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)

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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:

    View Slide

  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)

    View Slide

  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)

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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:

    View Slide

  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)

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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

    View Slide

  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)

    View Slide

  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:

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

  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)

    View Slide

  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:

    View Slide

  57. Worker pool (2/2)
    Queue
    Head

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

  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

    View Slide

  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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