[New-bugs-announce] [issue45241] python REPL leaks local variables when an exception is thrown

[Ian Henderson]

New submission from Ian Henderson <ian at ianhenderson.org>:

To reproduce, copy the following code:

----
import gc
gc.collect()
objs = gc.get_objects()
for obj in objs:
    try:
        if isinstance(obj, X):
            print(obj)
    except NameError:
        class X:
            pass

def f():
    x = X()
    raise Exception()

f()

----

then open a Python REPL and paste repeatedly at the prompt.  Each time the code runs, another copy of the local variable x is leaked.  This was originally discovered while using PyTorch -- tensors leaked this way tend to exhaust GPU memory pretty quickly.

Version Info:
Python 3.9.7 (default, Sep  3 2021, 04:31:11) 
[Clang 12.0.5 (clang-1205.0.22.9)] on darwin

----------
components: Interpreter Core
messages: 402144
nosy: ianh2
priority: normal
severity: normal
status: open
title: python REPL leaks local variables when an exception is thrown
type: resource usage
versions: Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue45241>
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