  In model serving, having one fixed model during the entire often life-long
inference process is usually detrimental to model performance, as data
distribution evolves over time, resulting in lack of reliability of the model
trained on historical data. It is important to detect changes and retrain the
model in time. The existing methods generally have three weaknesses: 1) using
only classification error rate as signal, 2) assuming ground truth labels are
immediately available after features from samples are received and 3) unable to
decide what data to use to retrain the model when change occurs. We address the
first problem by utilizing six different signals to capture a wide range of
characteristics of data, and we address the second problem by allowing lag of
labels, where labels of corresponding features are received after a lag in
time. For the third problem, our proposed method automatically decides what
data to use to retrain based on the signals. Extensive experiments on
structured and unstructured data for different type of data changes establish
that our method consistently outperforms the state-of-the-art methods by a
large margin.
