  Performance issues in cloud systems are hard to debug. Distributed tracing is
a widely adopted approach that gives engineers visibility into cloud systems.
Existing trace analysis approaches focus on debugging single request
correctness issues but not debugging single request performance issues.
Diagnosing a performance issue in a given request requires comparing the
performance of the offending request with the aggregate performance of typical
requests. Effective and efficient debugging of such issues faces three
challenges: (i) identifying the correct aggregate data for diagnosis; (ii)
visualizing the aggregated data; and (iii) efficiently collecting, storing, and
processing trace data.
  We present TraVista, a tool designed for debugging performance issues in a
single trace that addresses these challenges. TraVista extends the popular
single trace Gantt chart visualization with three types of aggregate data -
metric, temporal, and structure data, to contextualize the performance of the
offending trace across all traces.
