  Background. Coping with the rapid growing complexity in contemporary software
architecture, tracing has become an increasingly critical practice and been
adopted widely by software engineers. By adopting tracing tools, practitioners
are able to monitor, debug, and optimize distributed software architectures
easily. However, with excessive number of valid candidates, researchers and
practitioners have a hard time finding and selecting the suitable tracing tools
by systematically considering their features and advantages.Objective. To such
a purpose, this paper aims to provide an overview of popular Open tracing tools
via comparison. Method. Herein, we first identified \ra{30} tools in an
objective, systematic, and reproducible manner adopting the Systematic
Multivocal Literature Review protocol. Then, we characterized each tool looking
at the 1) measured features, 2) popularity both in peer-reviewed literature and
online media, and 3) benefits and issues. We used topic modeling and sentiment
analysis to extract and summarize the benefits and issues. Specially, we
adopted ChatGPT to support the topic interpretation. Results. As a result, this
paper presents a systematic comparison amongst the selected tracing tools in
terms of their features, popularity, benefits and issues. Conclusion. The
result mainly shows that each tracing tool provides a unique combination of
features with also different pros and cons. The contribution of this paper is
to provide the practitioners better understanding of the tracing tools
facilitating their adoption.
