APM Span

While we examine our spans, let’s look at several out-of-the-box features that you get without code modifications when using automatic discovery and configuration on top of tracing:

First, in the Waterfall Pane, make sure the customers-service:SELECT petclinic or similar span is selected as shown in the screenshot below:

DB-query DB-query

  • The basic latency information is shown as a bar for the instrumented function or call. In our example above, it took 17.8 Milliseconds.
  • Several similar Spans (1) are only visible if the span is repeated multiple times. In this case, there are 10 repeats in our example. You can show/hide them all by clicking on the 10x and all spans will show in order.
  • Inferred Services: Calls made to external systems that are not instrumented show up as a grey ‘inferred’ span. The Inferred Service or span in our example is a call to the Mysql Database mysql:petclinic SELECT petclinic (2) as shown above.
  • Span Tags: In the Tag Pane, we see standard tags produced by the automatic discovery and configuration. In this case, the span is calling a Database, so it includes the db.statement tag (3). This tag will hold the DB query statement and is used by the Database call performed during this span. This will be used by the DB-Query Performance feature. We look at DB-Query Performance in the next section.
  • Always-on Profiling: IF the system is configured to capture Profiling data during a Span life cycle. It will show the number of Call Stacks captured in the Spans timeline. In our example above, we see 18 Call Stacks for the customer-service:GET /owners Span. (4)

We will look at Profiling in the next section.