[New-bugs-announce] [issue28894] Memory leak in dict.pop()

[Marius Gedminas]

New submission from Marius Gedminas:

Run the following script with Python 3.6.0rc1:

    class O:
        pass

    o = O()
    for n in range(20):
        print(n)
        o.x = 42
        o.__dict__.pop('x', None)

You can observe the memory usage of the Python process growing exponentially.

E.g. in bash:

    ulimit -v 1000000    # don't push other processes into swap please
    python3.6 break.py
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    Traceback (most recent call last):
      File "break.py", line 7, in <module>
        o.x = 42
    MemoryError

----------
components: Interpreter Core
messages: 282623
nosy: mgedmin
priority: normal
severity: normal
status: open
title: Memory leak in dict.pop()
versions: Python 3.6, Python 3.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue28894>
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