'Commit offsets to kafka asynchronously, optionally firing callback.
This commits offsets only to Kafka. The offsets committed using this API
will be used on the first fetch after every rebalance and also on
startup. As such, if you need to store offsets in anything other than
Kafka, this API should not be used. To avoid re-processing the last
message read if a consumer is restarted, the committed offset should be
the next message your application should consume, i.e.: last_offset + 1.
This is an asynchronous call and will not block. Any errors encountered
are either passed to the callback (if provided) or discarded.
Arguments:
offsets (dict, optional): {TopicPartition: OffsetAndMetadata} dict
to commit with the configured group_id. Defaults to currently
consumed offsets for all subscribed partitions.
callback (callable, optional): Called as callback(offsets, response)
with response as either an Exception or an OffsetCommitResponse
struct. This callback can be used to trigger custom actions when
a commit request completes.
Returns:
kafka.future.Future'

def commit_async(self, offsets=None, callback=None):

    assert (self.config['api_version'] >= (0, 8, 1)), 'Requires    >=    Kafka    0.8.1'
    assert (self.config['group_id'] is not None), 'Requires    group_id'
    if (offsets is None):
        offsets = self._subscription.all_consumed_offsets()
    log.debug('Committing    offsets:    %s', offsets)
    future = self._coordinator.commit_offsets_async(offsets, callback=callback)
    return future
