In confluent_kafka.h this function has the following definition: #define cfl_PyUnistr_AsUTF8(X) PyBytes_AsString(PyUnicode_AsUTF8String(X))

The problems is that PyUnicode_AsUTF8String returns a new reference which is never released via Py_DECREF later on. Which means the return value of PyUnicode_AsUTF8String leaks memory.

I know a proper fix is hard, because the Py_DECREF must be deferred to the point where the result of PyUnicode_AsUTF8String is not used any more (considering also error cases ..).

I did not have problems with this leak yet, because the places where it happens are not triggered often in my code. However as soon as this is called frequently, for example TopicPartition_str0 with an errstr set, it will have an impact.