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reference leak when a JIT trace is rewound #157875
Description
Bug report
Bug description:
import gc
import sys
import weakref
def run():
class C:
def __iter__(self):
return self
def __next__(self):
raise StopIteration
obj = C()
for _ in range(10_000):
for _ in obj:
pass
return weakref.ref(C)
ref = run()
gc.collect()
print("jit enabled:", sys._jit.is_enabled())
print("leaked:", ref() is not None)This looks to be caused by value-recording uop (in the RECORD family) taking a strong reference to an object not being decref'd when traces are rewound
{
_PyUOpInstruction *curr = uop_buffer_last(trace);
while (curr->opcode != _SET_IP && uop_buffer_length(trace) > 2) {
trace->next--;
curr = uop_buffer_last(trace);
}
if (curr->opcode == _SET_IP) {
int32_t old_target = (int32_t)uop_get_target(curr);
curr->opcode = _DEOPT;
curr->format = UOP_FORMAT_TARGET;
curr->target = old_target;
}
goto done;
}
CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Activity
pythongh-157875: Fix reference leak when a JIT trace is rewound