The Tracing screen displays information about traces recorded during cluster operation. The recorded information can include informational messages, error messages, duration of specific operations, stack traces, etc. You can use this information to troubleshoot cluster operation or identify latency issues.
The screen displays a table containing all recorded traces, including the name of the event, its start time, duration and number of spans.
A trace is recorded information about the execution of a specific event. Each trace consists of a tree of spans. A span is an individual unit of work performed by the system in order to process the event.
A trace can include spans from multiple nodes.
To start configuring tracing, click the CONFIGURE TRACING button at the upper right corner of the page.
The Configure Tracing dialog box appears.
In the dialog box, perform the following:
Enable one or several scopes of the Configure Tracing dialog.
Choose one or several Included Scopes from the drop-down list for each scope and specify the percentage for the Sampling Rate field.
Click OK for the changes to take effect.
A span contains a set of tags and a set of logs attached to it. A tag is a key-value pair with information about the span. A log is a key-value pair with information about a specific moment or event within a span.
You can click on a trace name to view the spans included in the trace. The image below displays a trace with 3 spans.
The "discovery.custom.event" took 280 ms and consists of 2 spans.
You can also click on a span to view the tags and logs attached to the span.