Python3.10.5 Pattern Matching Excessive Memory Consumption · Issue #93671 · python/cpython (original) (raw)

Crash report

While writing some code to match a particularly complicated AST, I accidentally wrote a function whose definition causes the Python 3.10.5 interpreter to rapidly consume memory. On my system, it consumed approximately 24 GBs of memory before being killed.

The function is as follows:

def defines(self): match self.ast: case [S('CoqAst'), [[S('v'), [_, _, [S('expr'), [S('VernacDefinition'), [S('NoDischarge'), S('Definition')], [[[S('v'), [S('Name'), [S('Id'), S(name)]]], ], []], [S('DefineBody'), [], [], [, _], []]]]]], _]] | [S('CoqAst'), [[S('v'), [[S('control'), []], [S('attrs'), []], [S('expr'), [S('VernacStartTheoremProof'), S('Theorem'), [[[[[S('v'), [S('Id'), name]], _], []], _]]]]]], _]]: return name

To replicate, paste the above function into a python file and run it.

Error messages

OOM killing produced no output, save for Killed.

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