Va debugger ton Python!

Cette presentation vous explique les bases de Pdb ainsi que GDB, afin de debugger plus facilement vos scripts Python.

Transcript

1. Va debugger ton
   par
   Stéphane Wirtel
   PyCon FR 2017 - Toulouse - 23/09/2017
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2. Salut, je suis Stéphane
   par ma fille
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3. Qui aime developper... ?
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4. Debugger c'est Hard!
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5. Que fait ce code ?
   # Example 1
   def main():
   for i in range(1, 4):
   i /= 4
   if i == 4:
   print('Salut PyConFR 2017')
   if __name__ == '__main__':
   main()
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6. Que fait ce code ?
   # Example 1
   def main():
   for i in range(1, 4):
   i /= 4
   if i == 4:
   print('Salut PyConFR 2017')
   if __name__ == '__main__':
   main()
   $ python example1.py
   $
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7. La sacro-sainte fonction print()
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8. La sacro-sainte fonction print()
   # Example 2
   def main():
   for i in range(1, 4):
   i /= 4
   print(i)
   if i == 4:
   print('Salut PyConFR 2017')
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9. La sacro-sainte fonction print()
   # Example 2
   def main():
   for i in range(1, 4):
   i /= 4
   print(i)
   if i == 4:
   print('Salut PyConFR 2017')
   $ python example2.py
   0
   0
   0
   $
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10. Le module logging
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11. Utilisons logging
    # Example 3
    import logging
    def main():
    logging.basicConfig(level=logging.INFO)
    logging.info('start program')
    logging.debug("before loop")
    for i in range(1, 4):
    i /= 4
    logging.debug(i)
    logging.debug("after loop")
    if i == 4:
    print("Hello PyConFR 2017")
    logging.debug("Hello PyConFR 2017")
    logging.info('end program')
    if __name__ == '__main__':
    main()
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12. Utilisons logging
    # Example 3
    import logging
    def main():
    logging.basicConfig(level=logging.INFO)
    logging.info('start program')
    logging.debug("before loop")
    for i in range(1, 4):
    i /= 4
    logging.debug(i)
    logging.debug("after loop")
    if i == 4:
    print("Hello PyConFR 2017")
    logging.debug("Hello PyConFR 2017")
    logging.info('end program')
    if __name__ == '__main__':
    main()
    INFO:root:start program
    INFO:root:end program
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13. Utilisons logging
    # Example 4
    import logging
    def main():
    logging.basicConfig(level=logging.DEBUG)
    logging.info('start program')
    logging.debug("before loop")
    for i in range(1, 4):
    i /= 4
    logging.debug(i)
    logging.debug("after loop")
    if i == 4:
    print("Hello PyConFR 2017")
    logging.debug("Hello PyConFR 2017")
    logging.info('end program')
    if __name__ == '__main__':
    main()
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14. Utilisons logging
    INFO:root:start program
    DEBUG:root:before loop
    DEBUG:root:0
    DEBUG:root:0
    DEBUG:root:0
    DEBUG:root:after loop
    INFO:root:end program
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15. Utilisons logging
    INFO:root:start program
    DEBUG:root:before loop
    DEBUG:root:0
    DEBUG:root:0
    DEBUG:root:0
    DEBUG:root:after loop
    INFO:root:end program
    Obligé de modifier le niveau de log pour voir ce qu'il se passe.
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16. Cool
    mais
    Modification du code
    Execution
    Oubli de supprimer le print en production...
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17. que faire, quoi utiliser...
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18. Un debugger!
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19. PDB
    Python Debugger est l'outil natif pour aider les développeurs à trouver et
    corriger les bugs de leur logiciel fétiche (ou celui que l'on récupère d'un ancien
    collègue ou prestataire...)
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20. Eh oui, Python vient avec un debugger!
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21. Comment faire
    import pdb; pdb.set_trace()
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22. Comment faire
    import pdb; pdb.set_trace()
    # Example 5
    import pdb
    def main():
    for i in range(1, 4):
    i /= 4
    if i == 4:
    print("Hello PyConFR 2017")
    if __name__ == '__main__':
    pdb.set_trace()
    main()
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23. Comment faire
    import pdb; pdb.set_trace()
    # Example 5
    import pdb
    def main():
    for i in range(1, 4):
    i /= 4
    if i == 4:
    print("Hello PyConFR 2017")
    if __name__ == '__main__':
    pdb.set_trace()
    main()
    $ python example5.py
    > example5.py(7)main()
    -> for i in range(1, 4):
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24. Comment faire
    Example 6
    import pdb
    def do_something():
    raise Exception("bug")
    def main():
    try:
    do_something()
    except Exception:
    pdb.post_mortem()
    if __name__ == '__main__':
    main()
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25. Comment faire
    Example 6
    import pdb
    def do_something():
    raise Exception("bug")
    def main():
    try:
    do_something()
    except Exception:
    pdb.post_mortem()
    if __name__ == '__main__':
    main()
    > example6.py(4)do_something()
    -> raise Exception("bug")
    (Pdb) bt
    example6.py(8)main()
    -> do_something()
    > example6.py(4)do_something()
    -> raise Exception("bug")
    (Pdb) ll
    3 def do_something():
    4 -> raise Exception("bug")
    (Pdb)
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26. Comment faire
    On peut aussi charger pdb comme un module à la ligne de commande.
    $ python -m pdb
    $ python -m pdb -c "command"
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27. Prenons un exemple lisant un .csv
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28. Prenons un exemple lisant un .csv
    import pendulum
    import csv
    class Event:
    def __init__(self, name, date):
    self.name = name
    self.date = pendulum.parse(date)
    def get_events(stream):
    for row in csv.reader(stream):
    yield Event(*row)
    def main():
    with open('events.csv') as stream:
    for event in get_events(stream):
    print(event.name, event.date)
    if __name__ == '__main__':
    main()
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29. Prenons un exemple lisant un .csv
    import pendulum
    import csv
    class Event:
    def __init__(self, name, date):
    self.name = name
    self.date = pendulum.parse(date)
    def get_events(stream):
    for row in csv.reader(stream):
    yield Event(*row)
    def main():
    with open('events.csv') as stream:
    for event in get_events(stream):
    print(event.name, event.date)
    if __name__ == '__main__':
    main()
    PyCon France,2017-09-21
    PyCon Canada,2017-11-18
    PyCon US,2017-05-17
    Python FOSDEM,2018-02-03
    Python TOTO,x
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30. Prenons un exemple lisant un .csv
    $ python events.py
    Non d'un petit Python, CRASH avec deux exceptions :/
    PyCon France 2017-09-21T00:00:00+00:00
    PyCon Canada 2017-11-18T00:00:00+00:00
    PyCon US 2017-05-17T00:00:00+00:00
    Python FOSDEM 2018-02-03T00:00:00+00:00
    File "/home/stephane/.virtualenvs/flask/lib/python3.6/site-packages/dateutil/par
    raise ValueError("Unknown string format")
    ValueError: Unknown string format
    During handling of the above exception, another exception occurred:
    File "/home/stephane/.virtualenvs/flask/lib/python3.6/site-packages/pendulum/par
    raise ParserError('Invalid date string: {}'.format(text))
    pendulum.parsing.exceptions.ParserError: Invalid date string: x
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31. Je débugge
    $ python -m pdb events.py
    > events.py(1)()
    -> import pendulum
    (Pdb)
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32. Je liste mon code avec l ou ll
    (Pdb) ll
    1 -> import pendulum
    2 import csv
    3
    4 class Event:
    5 def __init__(self, name, date):
    6 self.name = name
    7 self.date = pendulum.parse(date)
    8
    9 def get_events(stream):
    10 for row in csv.reader(stream):
    11 yield Event(*row)
    12
    13 def main():
    14 with open('events.csv') as stream:
    15 for event in get_events(stream):
    16 print(event.name, event.date)
    17
    18 if __name__ == '__main__':
    19 main()
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33. J'avance d'une ligne
    (Pdb) next
    > events.py(2)()
    -> import csv
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34. J'avance d'une ligne
    (Pdb) next
    > events.py(2)()
    -> import csv
    (Pdb) ll
    1 import pendulum
    2 -> import csv
    3
    4 class Event:
    5 def __init__(self, name, date):
    6 self.name = name
    7 self.date = pendulum.parse(date)
    8
    9 def get_events(stream):
    10 for row in csv.reader(stream):
    11 yield Event(*row)
    12
    13 def main():
    14 with open('events.csv') as stream:
    15 for event in get_events(stream):
    16 print(event.name, event.date)
    17
    18 if __name__ == '__main__':
    19 main()
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35. On saute dans le code
    -> def main():
    (Pdb) ll
    15 -> def main():
    16 with open('events.csv') as stream:
    17 for event in get_events(stream):
    18 print(event.name, event.date)
    19 print(Event.id)
    (Pdb) step
    > events.py(16)main()
    -> with open('events.csv') as stream:
    (Pdb) ll
    15 def main():
    16 -> with open('events.csv') as stream:
    17 for event in get_events(stream):
    18 print(event.name, event.date)
    19 print(Event.id)
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36. On saute dans le code
    (Pdb) next
    > events.py(17)main()
    -> for event in get_events(stream):
    (Pdb) ll
    15 def main():
    16 with open('events.csv') as stream:
    17 -> for event in get_events(stream):
    18 print(event.name, event.date)
    19 print(Event.id)
    (Pdb) step
    --Call--
    > events.py(11)get_events()
    -> def get_events(stream):
    (Pdb) ll
    11 -> def get_events(stream):
    12 for row in csv.reader(stream):
    13 yield Event(*row)
    (Pdb) next
    > events.py(12)get_events()
    -> for row in csv.reader(stream):
    (Pdb) ll
    11 def get_events(stream):
    12 -> for row in csv.reader(stream):
    13 yield Event(*row)
    (Pdb)
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37. Breakpoints
    Je reprends le code de base
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38. Breakpoints
    (Pdb) ll
    1 import pendulum
    2 import csv
    3
    4 class Event:
    5 def __init__(self, name, date):
    6 self.name = name
    7 self.date = pendulum.parse(date)
    8
    9 def get_events(stream):
    10 for row in csv.reader(stream):
    11 yield Event(*row)
    12
    13 def main():
    14 with open('events.csv') as stream:
    15 for event in get_events(stream):
    16 print(event.name, event.date)
    17
    18 if __name__ == '__main__':
    19 main()
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39. Breakpoints
    Lister
    > events.py(1)()
    -> import pendulum
    (Pdb) break
    (Pdb)
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40. Breakpoints
    Ajouter
    > events.py(1)()
    -> import pendulum
    (Pdb) break 9
    Breakpoint 1 at events.py:9
    (Pdb) l
    4 class Event:
    5 id = 0
    6 def __init__(self, name, date):
    7 self.id += 1
    8 self.name = name
    9 B-> self.date = pendulum.parse(date)
    10
    11 def get_events(stream):
    12 for row in csv.reader(stream):
    13 yield Event(*row)
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41. Breakpoints
    Ajouter
    > events.py(1)()
    -> import pendulum
    (Pdb) break 9
    Breakpoint 1 at events.py:9
    (Pdb) l
    4 class Event:
    5 id = 0
    6 def __init__(self, name, date):
    7 self.id += 1
    8 self.name = name
    9 B-> self.date = pendulum.parse(date)
    10
    11 def get_events(stream):
    12 for row in csv.reader(stream):
    13 yield Event(*row)
    (Pdb) break
    Num Type Disp Enb Where
    1 breakpoint keep yes at events.py:9
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42. Breakpoints
    Désactiver un breakpoint
    (Pdb) disable 1
    Disabled breakpoint 1 at events.py:9
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43. Breakpoints
    Désactiver un breakpoint
    (Pdb) disable 1
    Disabled breakpoint 1 at events.py:9
    (Pdb) break
    Num Type Disp Enb Where
    1 breakpoint keep no at events.py:9
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44. Breakpoints
    Activer un breakpoint
    (Pdb) enable 1
    Enabled breakpoint 1 at events.py:9
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45. Breakpoints
    Activer un breakpoint
    (Pdb) enable 1
    Enabled breakpoint 1 at events.py:9
    (Pdb) break
    Num Type Disp Enb Where
    1 breakpoint keep yes at events.py:9
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46. Je continue
    (Pdb) continue
    > events.py(9)__init__()
    -> self.date = pendulum.parse(date)
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47. J'examine
    (Pdb) args
    self = <__main__.Event object at 0x7f23cf8cc908>
    name = 'PyCon France'
    date = '2017-09-21'
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48. J'examine
    (Pdb) args
    self = <__main__.Event object at 0x7f23cf8cc908>
    name = 'PyCon France'
    date = '2017-09-21'
    (Pdb) whatis name
    
    (Pdb) whatis self
    
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49. Nouvelles commandes avec alias
    alias d pp dir(%1)
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50. Nouvelles commandes avec alias
    alias d pp dir(%1)
    (Pdb) b 9
    Breakpoint 1 at events.py:9
    (Pdb) c
    > events.py(9)__init__()
    -> self.date = pendulum.parse(date)
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51. Nouvelles commandes avec alias
    alias d pp dir(%1)
    (Pdb) b 9
    Breakpoint 1 at events.py:9
    (Pdb) c
    > events.py(9)__init__()
    -> self.date = pendulum.parse(date)
    (Pdb) d self.__dict__
    ['__class__',
    '__contains__',
    '__delattr__',
    ...
    ]
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52. Nouvelles commandes avec alias
    alias loc !list(locals().keys())
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53. Nouvelles commandes avec alias
    alias loc !list(locals().keys())
    (Pdb) loc
    dict_keys(['date', 'name', 'self'])
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54. Nouvelles commandes avec alias
    alias printdict for key, value in %1.items(): print(f"{key}:{value}")
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55. Nouvelles commandes avec alias
    alias printdict for key, value in %1.items(): print(f"{key}:{value}")
    (Pdb) printdict self.__dict__
    id:1
    name:PyCon France
    date:2017-09-21T00:00:00+00:00
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56. Réutilisation d'alias
    alias pd printdict %1
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57. Réutilisation d'alias
    alias pd printdict %1
    (Pdb) pd self.__dict__
    id:1
    name:PyCon France
    date:2017-09-21T00:00:00+00:00
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58. Breakpoint et une action
    Possibilité de définir une action lors d'un breakpoint
    commands [bpnumber]
    p self.__dict__
    printdict self.__dict__
    end
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59. Démonstration
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60. PDB
    Récapitulatif des commandes
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61. Les importantes
    Commande Description
    h(elp) Affiche l'aide
    h(elp) command Affiche l'aide d'une commande
    q(uit) Quitte le debuggeur
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62. Examiner
    Commande Description
    p(rint) expr Affiche la valeur de l'expression
    pp expr Pretty-print de la valeur de l'expression
    l(ist) Affiche une partie du code
    ll Affiche toute le code de la fonction
    a(rgs) Affiche la liste des arguments de la fonction
    whatis arg Affiche le type de l'argument
    where Mais ou se trouve l'exception
    source Affiche la source d'une fonction
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63. Naviguer
    Commande Description
    n(ext) Exécute l'instruction
    s(tep) Exécute et rentre dans la fonction/méthode
    r(eturn) Continue l'exécution jusqu'au return
    c(ontinue) Continue l'exécution jusqu'à un breakpoint
    u(p) Remonte d'un niveau dans la stack trace
    d(own) Descend d'un niveau dans la stack trace
    j(ump) lineno Saute a la ligne
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64. Breakpoints
    Commande Description
    b(reak) Montre tous les breakpoints
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65. Breakpoints
    Commande Description
    b(reak) lineno Place un breakpoint à lineno
    b(reak) lineno,
    cond
    Place un breakpoint à lineo si cond est True
    b(reak)
    file:lineno
    Place un breakpoint dans le fichier file à la ligne
    lineno
    b(reak) func
    Place un breakpoint à la première ligne de la
    fonction func
    tbreak lineno Place un breakpoint et l'enleve dès que l'on y est
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66. Breakpoints
    Commande Description
    clear bpnumber Supprime un breakpoint
    disable bpnumber Désactive un breakpoint
    enable bpnumber Active un breakpoint
    ignore bpnumber count Ignore le breakpoint X fois
    condition bpnumber condition Permet de modifer le breakpoint
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67. Celles que vous ne connaissez pas ;-)
    Commande Description
    !expr
    Execute une expression dans l'interpreteur
    Python
    alias Créer une nouvelle commande PDB
    unalias Supprime un alias
    commands
    [bpnumber]
    Assigne des commandes à un breakpoint
    restart or run Redémarre le script
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68. Fichier de con guration
    alias d pp dir(%1)
    alias ps d self.__dict__
    alias loc !list(locals().keys())
    alias printdict for key, value in %1.items(): print(f"{key}:{value}")
    Voir $HOME/.pdbrc ou ./.pdbrc
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69. Il y a un truc amusant
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70. Ça fonctionne avec ipdb
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71. Les alternatives - ipdb
    Auto-completion
    Coloration syntaxique
    Meilleurs tracebacks
    Meilleur introspection
    Commandes supplémentaires
    https://github.com/gotcha/ipdb
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72. Les alternatives - pudb
    https://github.com/inducer/pudb
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73. Les alternatives - rdb
    import pdb, socket, sys # noqa --> Pas PEP8
    class Rdb(pdb.Pdb):
    def __init__(self, port=4444):
    self.old_stdout = sys.stdout
    self.old_stdin = sys.stdin
    self.skt = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    self.skt.bind(('localhost', port))
    self.skt.listen(1)
    (clientsocket, address) = self.skt.accept()
    handle = clientsocket.makefile('rw')
    pdb.Pdb.__init__(self, completekey='tab', stdin=handle, stdout=handle)
    sys.stdout = sys.stdin = handle
    def do_continue(self, arg):
    sys.stdout = self.old_stdout
    sys.stdin = self.old_stdin
    self.skt.close()
    self.set_continue()
    return 1
    do_c = do_cont = do_continue
    https://dzone.com/articles/remote-debugging-python-using
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74. Les alternatives - rdb (2)
    # Example usage - connect with 'telnet 4444'
    if __name__=='__main__':
    def buggy_method():
    x = 3
    remote_debug = Rdb()
    remote_debug.set_trace()
    print(x)
    buggy_method()
    https://dzone.com/articles/remote-debugging-python-using
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75. Les alternatives - rdb (3)
    telnet localhost 4444
    Trying 127.0.0.1...
    Connected to localhost.
    Escape character is '^]'.
    > rdb.py(32)buggy_method()
    -> print(x)
    (Pdb) ll
    28 def buggy_method():
    29 x = 3
    30 remote_debug = Rdb()
    31 remote_debug.set_trace()
    32 -> print(x)
    (Pdb) p x
    3
    (Pdb) quit
    Connection closed by foreign host.
    Meilleure implémentation dans
    https://github.com/celery/celery/blob/master/celery/contrib/rdb.py
    https://dzone.com/articles/remote-debugging-python-using
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76. Les alternatives - wdb
    https://github.com/Kozea/wdb
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77. Les alternatives - pdbpp
    https://github.com/antocuni/pdb
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78. pdb ou ipdb avec du dev Web
    Par exemple, Django
    django-pdb avec --ipdb ou --pdb
    ou simplement
    python -m pdb ./manage.py test
    python -m ipdb ./manage.py test
    python -m pudb ./manage.py test
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79. GNU Debugger
    Également nommé gdb, GNU Debugger, est le débuggeur standard du projet
    GNU, portable et fonctionne pour plusieurs langages, comme le C, le C++ et aussi
    le Python ;-)
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80. GNU Debugger
    gdb >= 7 , support natif de Python
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81. GNU Debugger
    Avoir les symboles de debug de Python
    $ dnf install python3-debug
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82. GNU Debugger
    Avoir les symboles de debug de Python
    $ dnf install python3-debug
    ou
    $ ./configure --prefix=$PWD-build --with-pydebug
    $ make
    $ make install
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83. GNU Debugger
    Python + gdb = ?
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84. GNU Debugger
    Python + gdb = ?
    1. il y a une librairie pour debugger votre script Python depuis gdb
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85. GNU Debugger
    Python + gdb = ?
    1. il y a une librairie pour debugger votre script Python depuis gdb
    2. gdb est extensible via Python
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86. Que faire avec gdb ?
    Commande Description
    py-bt Montre la stack trace Python
    py-bt-full py-bt mais en plus verbeux
    py-list Liste le code Python
    py-print Affiche le contenu d'une variable Python
    py-locals Affiche les locals
    py-up Remonte d'une frame
    py-down Descend d'une frame
    85 / 107
    

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87. Le code
    import time
    import os
    def next(i):
    print(f"{os.getpid()} {time.strftime('%H:%M:%S')}")
    time.sleep(10)
    i = 1 - i
    i = 1
    while True:
    next(i)
    86 / 107
    

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88. Le code
    import time
    import os
    def next(i):
    print(f"{os.getpid()} {time.strftime('%H:%M:%S')}")
    time.sleep(10)
    i = 1 - i
    i = 1
    while True:
    next(i)
    $ python ex_loop1.py
    10619 06:14:24
    10619 06:14:34
    10619 06:14:44
    10619 06:14:54
    10619 06:15:04
    10619 06:15:14
    PID 10619
    87 / 107
    

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89. Comment faire ?
    $ gdb -p 10619
    GNU gdb (GDB) Fedora 8.0.1-26.fc26
    ...
    For help, type "help".
    Type "apropos word" to search for commands related to "word".
    Attaching to process 10619
    Reading symbols from /usr/bin/python3.6dm...Reading symbols from /usr/lib/debug/us
    Reading symbols from /lib64/libpython3.6dm.so.1.0...Reading symbols from /usr/lib/d
    Reading symbols from /lib64/libpthread.so.0...Reading symbols from /usr/lib/debug/
    [Thread debugging using libthread_db enabled]
    Using host libthread_db library "/lib64/libthread_db.so.1".
    Reading symbols from /lib64/libdl.so.2...Reading symbols from /usr/lib/debug/usr/li
    Reading symbols from /lib64/libutil.so.1...Reading symbols from /usr/lib/debug/usr
    Reading symbols from /lib64/libm.so.6...Reading symbols from /usr/lib/debug/usr/li
    Reading symbols from /lib64/libc.so.6...Reading symbols from /usr/lib/debug/usr/li
    Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/de
    0x00007f40dc696ce3 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:84
    84 T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
    (gdb)
    88 / 107
    

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90. A cher le code
    (gdb) py-list
    1 import time
    2 import os
    3
    4 def next(i):
    5 print(f"{os.getpid()} {time.strftime('%H:%M:%S')}")
    >6 time.sleep(10)
    7 i = 1 - i
    8
    9 i = 1
    10 while True:
    11 next(i)
    (gdb)
    89 / 107
    

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91. A cher la traceback
    (gdb) py-bt
    Traceback (most recent call first):
    
    File "ex_loop1.py", line 6, in next
    time.sleep(10)
    File "ex_loop1.py", line 11, in
    next(i)
    90 / 107
    

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92. A cher la traceback avec plus d'infos
    (gdb) py-bt-full
    #3
    #7 Frame 0x55c890804748, for file ex_loop1.py, line 6, in next (i=1)
    time.sleep(10)
    #12 Frame 0x55c890804458, for file ex_loop1.py, line 11, in ()
    next(i)
    91 / 107
    

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93. A cher la traceback avec plus d'infos
    (gdb) py-bt-full
    #3
    #7 Frame 0x55c890804748, for file ex_loop1.py, line 6, in next (i=1)
    time.sleep(10)
    #12 Frame 0x55c890804458, for file ex_loop1.py, line 11, in ()
    next(i)
    (gdb) select-frame 7
    (gdb) info locals
    tstate = 0x55c8907a3cf0
    (gdb) select-frame 3
    (gdb) info locals
    func = 0x7f40d5974418
    meth = 0x7f40dd57c6c6
    self =
    result = 'sleep'
    flags = 8
    __PRETTY_FUNCTION__ = "_PyCFunction_FastCallDict"
    92 / 107
    

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94. Examiner une frame
    (gdb) py-bt-full
    #3
    #7 Frame 0x55706036f748, for file ex_loop1.py, line 6, in next (i=1)
    time.sleep(10)
    #12 Frame 0x55706036f458, for file ex_loop1.py, line 11, in ()
    next(i)
    (gdb) select-frame 7
    (gdb) py-list
    1 import time
    2 import os
    3
    4 def next(i):
    5 print(f"{os.getpid()} {time.strftime('%H:%M:%S')}")
    >6 time.sleep(10)
    7 i = 1 - i
    8
    9 i = 1
    10 while True:
    11 next(i)
    (gdb) py-print i
    local 'i' = 1
    (gdb) py-locals
    i = 1
    93 / 107
    

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95. Navigation
    (gdb) py-down
    Unable to find a newer python frame
    (gdb) py-up
    #7 Frame 0x55c890804748, for file ex_loop1.py, line 6, in next (i=1)
    time.sleep(10)
    (gdb) py-down
    #3
    94 / 107
    

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96. Backtrace de CPython
    (gdb) bt
    #0 0x00007f40dc696ce3 in __select_nocancel () at ../sysdeps/unix/syscall-template
    #1 0x00007f40dd57e7f8 in pysleep (secs=10000000000)
    at /usr/src/debug/Python-3.6.2/Modules/timemodule.c:1438
    #2 0x00007f40dd57c73d in time_sleep (self=, obj=
    at /usr/src/debug/Python-3.6.2/Modules/timemodule.c:235
    #3 0x00007f40dd39a9af in _PyCFunction_FastCallDict (
    func_obj=,
    args=0x55c8908048e0, nargs=1, kwargs=0x0)
    at /usr/src/debug/Python-3.6.2/Objects/methodobject.c:209
    #4 0x00007f40dd39ada6 in _PyCFunction_FastCallKeywords (
    func=,
    stack=0x55c8908048e0, nargs=1, kwnames=0x0)
    at /usr/src/debug/Python-3.6.2/Objects/methodobject.c:294
    #5 0x00007f40dd4b046e in call_function (pp_stack=0x7ffd7bcab7b8, oparg=1, kwnames=
    at /usr/src/debug/Python-3.6.2/Python/ceval.c:4809
    #6 0x00007f40dd4a8046 in _PyEval_EvalFrameDefault (
    f=Frame 0x55c890804748, for file ex_loop1.py, line 6, in next (i=1), throwflag=
    at /usr/src/debug/Python-3.6.2/Python/ceval.c:3295
    #7 0x00007f40dd494118 in PyEval_EvalFrameEx (
    f=Frame 0x55c890804748, for file ex_loop1.py, line 6, in next (i=1), throwflag=
    at /usr/src/debug/Python-3.6.2/Python/ceval.c:718
    95 / 107
    

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97. Threads
    (gdb) info threads
    Id Target Id Frame
    1 Thread 0x7f40ddaef700 (LWP 10619) "python3-debug" 0x00007f40dd39a9af in _PyC
    args=0x55c8908048e0, nargs=1, kwargs=0x0)
    at /usr/src/debug/Python-3.6.2/Objects/methodobject.c:209
    96 / 107
    

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98. Dumper les stack traces des threads
    (gdb) thread apply all py-bt
    Thread 1 (Thread 0x7f40ddaef700 (LWP 10619)):
    Traceback (most recent call first):
    
    File "ex_loop1.py", line 6, in next
    time.sleep(10)
    File "ex_loop1.py", line 11, in
    next(i)
    (gdb)
    97 / 107
    

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99. Débugger à distance
    98 / 107
    

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100. Mode Remote - gdbserver
     $ gdbserver --multi host:2345
     #
     # ou ces modes-ci
     #
     $ gdbserver host:2345 process_name
     $ gdbserver host:2345 --attach PID
     99 / 107
     

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101. Mode Remote - gdbserver
     $ gdbserver --multi host:2345
     #
     # ou ces modes-ci
     #
     $ gdbserver host:2345 process_name
     $ gdbserver host:2345 --attach PID
     $ gdb
     (gdb) target extended-remote host:2345
     (gdb) attach PID
     100 / 107
     

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102. Mode Remote - gdbserver
     $ gdbserver --multi host:2345
     #
     # ou ces modes-ci
     #
     $ gdbserver host:2345 process_name
     $ gdbserver host:2345 --attach PID
     $ gdb
     (gdb) target extended-remote host:2345
     (gdb) attach PID
     (gdb) py-list
     1 import time
     2 import os
     3
     4 def next(i):
     5 print(f"{os.getpid()} {time.strftime('%H:%M:%S')}")
     >6 time.sleep(10)
     7 i = 1 - i
     8
     9 i = 1
     10 while True:
     11 next(i)
     (gdb)
     101 / 107
     

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103. Extensible ?
     102 / 107
     

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104. Extensible ? - Oui
     https://github.com/cyrus-and/gdb-dashboardOui
     103 / 107
     

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105. Alternatives
     104 / 107
     

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106. gdbgui
     pip install gdbgui
     105 / 107
     

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107. Prochaines talks pour 2018
     SystemTap et DTrace pour mon Python
     Que fait mon débuggeur Python?
     GDB en profondeur
     106 / 107
     

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108. Questions ?
     stephane@mgx.io
     107 / 107
     

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