The HTrace incubator project has voted to retire itself and won't be making further releases. The Hadoop project currently has various hooks with HTrace. It seems in some cases (eg
HDFS-13702) these hooks have had measurable performance overhead. Given these two factors, I think we should consider removing the HTrace integration. If there is someone willing to do the work, replacing it with OpenTracing might be a better choice since there is an active community.