on master (commit 9ac3cb1) https://github.com/dpkp/kafka-python/blob/master/kafka/consumer/group.py ,
method def poll(self, timeout_ms=0, max_records=None) uses time.time() to calculate elapsed time.
time.time() does not return a monotonic clock , and therefore the elapsed time calculation could yield unexpected results.

>>> time.get_clock_info('time')
namespace(adjustable=True, implementation='clock_gettime(CLOCK_REALTIME)', monotonic=False, resolution=1.0000000000000002e-06)

the time module has several monotonic times available, but I don't believe they're available for python 2, which this library supports