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Investigate a trace

This guide shows how to investigate a single trace from the grid down to its root cause in the Diagnostics cube.

Find a trace worth examining

  1. Press M for the Traces & Logs Camera View. This is a top-down view looking down on the field of trace blocks.
  2. Click a trace cube to port down onto the grid at that cube's location. You land on the grid, standing on the skyline right next to the cube you picked.
  3. Read the skyline around you. Read height and color together:
    • A tall Trace Aggregate Block is a slow trace (height grows with the combined span duration).
    • A red block is a failed trace (an error span or error log).
    • An orange Log Aggregate Block has a warning log but no error.
    • A black Trace Aggregate Block is a trace missing a span.
  4. Hover a block for its tooltip to read the error text and trace details, then press F6 to copy. The details are in the tooltip, not printed on the block face.

Send the trace to Diagnostics

  1. Click the rhombus next to the Trace Aggregate Block you want to examine.
  2. You zoom deeper into that trace and arrive inside the Diagnostics cube, where Tessa's context is focused on it.

Read the two walls

Inside Diagnostics, the trace un-flattens into two walls.

  1. Read the span waterfall (north). Spans render as 3D bars stepping down and to the right. Bar length is span duration. Red spans are errored. For a large waterfall, jump to start swimming and move up and around the bars to read it from any angle.
  2. Read the logs wall (west). Logs stack as horizontal bars, color-coded by level. The actual log text is readable on each bar.
  3. Trace the root cause: follow the waterfall to the point it turns red, then read the logs at that same point for the reason.

Verification: you are now standing inside the trace, with the logs wall and the span waterfall both visible around you.

Alternative: ask Tessa which trace to look at

  1. From a service platform, press F12 to open the Tessa console.
  2. Ask Tessa which trace is slow or failing, and let her point you to it.
  3. Go to that trace on the grid and enter it through its Trace Aggregate Block's rhombus, as above. Entering the Diagnostics cube is always done from the grid block, not from the console.