Understand and use distributed trace UI

New Relic's distributed tracing helps you monitor and analyze the behavior of your distributed system. This document contains details about the UI and how to use it.

Access to this feature requires APM Pro and enabling of distributed tracing.

Related documentation:

Get started

There are two main UI pages for distributed tracing:

To find distributed trace data:

In New Relic One

Go to one.newrelic.com > Entity explorer > (select a service) > Distributed tracing.

For tips on getting around in New Relic One, see Intro to New Relic One.

For additional distributed tracing features in New Relic One, see Additional features.

In New Relic APM

Go to rpm.newrelic.com/apm > (select an application) > Distributed tracing.

Examples of problem-solving

Here are some examples of using distributed tracing to solve problems:

Diagnosing and fixing a latency issue
  1. An engineer receives an alert notification showing that their service is experiencing frequent high latency.
  2. The engineer goes to the APM Overview page and sees a large increase in response time from dependent services.
  3. They go to the list of traces and applies a filter for duration > 2, so they can look at only the traces with spans over that duration.
  4. They select a trace with unusually long latency. On the trace details page, they see there's a call being made to a dependent service that is querying a database that is responding very slowly.
  5. They check with the owner of that service and learn that that team is currently working on scaling the database due to unexpected high throughput.
Analyzing errors in requests spanning multiple services
  1. An engineer is tasked with troubleshooting errors occuring in a complex transaction spanning many services.
  2. They go to the list of traces and filter down to that specific request.
  3. They filter down to show only traces containing errors.
  4. On the trace details page, they can see the span along the request route that originated the error.
  5. Noting the error class and message, they navigate to the service from its span in the trace and see that the error is occurring at a high rate. They ask the service owner to look into that error.

Trace list UI

New Relic distributed tracing main page with numbers
rpm.newrelic.com/apm > (select an application) > Distributed tracing: On this page, you can see all the traces available and filter down to those having specific criteria. (This screenshot shows New Relic APM, not New Relic One distributed tracing.)

Here are some features of the main Distributed tracing UI page (screenshot above):

  1. Trace scatter plot: Shows a plot of traces that lets you easily see outliers. Select a plot point to see details for that trace.
  2. Trace list: Shows a list of traces, along with information like the root span duration, the number of spans in a trace, the number of errors, and the number of services. Select a trace to see trace details.
  3. Filter: View only traces that contain spans with certain traits. For advanced options, select the filter dropdown. For details on using feature, see Filter details.
  4. Group by: Group the displayed trace scatter plot in different ways. For more on the grouping options, see Trace grouping.

Trace details UI

New Relic distributed tracing waterfall page with numbers
rpm.newrelic.com/apm > (select an application) > Distributed tracing > (select a trace) > (select a span): See the details for a trace. Examine individual spans and see notifications for spans with anomalous behavior. (This screenshot shows New Relic APM, not New Relic One distributed tracing.)

When a trace is selected, you see details for that trace (see screenshot above):

  1. Trace timeline: Gives a visual representation of the trace over time. To zoom in on a specific time range of the trace, click and drag over an area. Red spans indicate errors.
  2. Trace waterfall: Displays the spans in a trace. Red spans indicate errors. Also displays anomalous spans and time differences between client and server spans. In-process spans are initially collapsed but can be expanded.
  3. Service colors. Select the Services dropdown to see the services displayed in the trace and their colors.
  4. Anomalous spans detected: Displays a count of anomalous spans. Select the dropdown for links to those spans.
  5. Span details: Select a span to see details, such as charts, attributes, anomalous span data, and the full span name. Different span types will have different charts and details available.

For technical details about some UI components, and some commonly asked questions, see UI details.

For more on how spans are created, see Distributed tracing explained.

Span types

There are four types of spans:

Span type UI icon Description
Datastore New Relic distributed tracing datastore span icon Represents a call to a datastore service. Datastore span events have a category of datastore.
External New Relic distributed tracing external span icon Represents a call to an external service made via HTTP. External span events have a category of http.
Service New Relic distributed tracing datastore span icon Represents the entry point into a service monitored by New Relic APM.
In-process New Relic distributed tracing in-process span icon Represents a span that takes place within a process (as opposed to cross-process spans, which cross process boundaries). Examples: middleware instrumentation, user-created spans. Service span events have a category of generic.

Some spans in the UI may be marked as anomalous.

Trace grouping options

When viewing the trace scatter plot, there are several Group traces by options:

  • Errors: Group by whether traces contain errors or not.
  • Root service: Group by the name of the first service in traces. In a trace where Service A calls Service B and Service B calls Service C, the root service would be Service A.
  • Root entry span: Group by the root transaction: in other words, the root service's endpoint. In a trace where Service A calls Service B and Service B calls Service C, the root entry span is Service A's endpoint. For example: "Service A - GET /user/%".
  • Service entry span: Group by the span name of the service currently being viewed in APM. For example, for a trace where Service A calls Service B and Service B calls Service C: if you are viewing Service B in APM and select this grouping, the traces will be represented by their Service B span names. If a service has multiple spans in a trace, this grouping option will use that service's first entry point.

Query data in Insights

For how to query distributed tracing data in New Relic Insights, see Example Insights queries.

Additional UI details

Here are some additional distributed tracing rules and limits:

Anomalous spans

If a span is displayed as anomalous in the UI, it means that the following are both true:

  • The span is more than two standard deviations slower than the average of all spans with the same name from the same service over the last six hours.
  • The span's duration is more than 10% of the trace's duration.
Time differences between client and server spans

When a process calls another process, and both processes are instrumented by New Relic, the trace contains both a client-side representation of the call and a server-side representation. The client span (calling process) can have time-related differences when compared to the server span (called process). These differences could be due to:

  • Clock skew, due to system clock time differences
  • Differences in duration, due to things like network latency or DNS resolution delay

The UI shows these time-related differences by displaying an outline of the client span in the same space as the server span. This span represents the duration of the client span.

It isn't possible to determine every factor contributing to these time-related discrepancies, but here are some common span patterns and tips for understanding them:

New Relic distributed tracing client vs server time discrepancy diagram
  1. When a client span is longer than the server span, this could be due to latency in a number of areas, such as: network time, queue time, DNS resolution time, or from a load balancer that we cannot see.
  2. When a client span starts and ends before a server span begins, this could be due to clock skew, or due to the server doing asynchronous work that continues after sending the response.
  3. When a client span starts after a server span, this is most likely clock skew.
Filter details

There are differences in how trace filtering works in New Relic One and New Relic APM:

New Relic APM

Some rules governing trace filtering:

  • Filtering based on current application. The attributes available for filtering are only those available in the application you are currently viewing in New Relic. If you do not see attributes you expect to see, it's probably because they are not available for the application you are viewing. If that is the case, you will need to go to the application index and select the application where those attributes are captured.
  • Multi-attribute filter affected by first attribute selected. There are two types of event data distributed tracing reports: transaction events and span events. When you select an attribute in the filter, the event that attribute is attached to will dictate the available attributes. For example, if you filter on an attribute that is attached to a Transaction event, only Transaction event attributes will be available when you attempt to add filter on additional attribute values.
New Relic One

In New Relic One distributed tracing, you can search for attributes from across all spans in a trace.

For details, see Distributed tracing in New Relic One.

Lines between spans: dotted vs solid

In the waterfall view, lines between spans are either solid or dotted. Solid lines indicate a direct parent-child relationship; in other words, one process or function directly calling another. A dotted line indicates a non-direct relationship.

Trace details obfuscated based on account access

If you don’t have access to the New Relic accounts that monitor other services, some of the span and service details will be obfuscated in the UI. Obfuscation can include:

  • Span name concealed by asterisks
  • Service name replaced with New Relic account ID and app ID

The two main factors affecting this obfuscation:

  • Account permissions. Master/sub-account relationships will impact access. If you have access to only a sub-account, you’ll be able to see details for only that sub-account. If you have access to a master account, you’ll be able to see details for that account’s sub-accounts.
  • Authentication. You’ll be able to see span details only for New Relic accounts you can access based on your current login. This means that, for example, even the admin of a master account may not be able to see all details if the trace crosses the boundaries of different authentication mechanisms.
Span collection and display limits, and sampling details

New Relic APM agents have a limit of 1,000 on the number of spans that can be collected per agent instance. The agents use sampling to select the requests chosen for a trace. For more on sampling and agent span limits, see Sampling.

The maximum total number of spans displayed in the UI is 10,000.

Missing spans and span/service count discrepancies

A trace may sometimes have (or seem to have) missing spans or services. This can manifest as a discrepancy between the count of a trace's spans or services displayed in the trace list and the count displayed on the trace details page.

Reasons for missing spans and count discrepancies include:

  • An APM agent may have hit its 1K span collection limit.
  • A span may be initially counted but not make it into a trace display, for reasons such as network latency or a query issue.
  • If an APM-monitored application reports as multiple app names, the trace waterfall view will display a single span for that service, but will actually report multiple span events, one for each application name.
  • The UI may have hit its 10K span display limit.

All spans collected, including those not displayed, can be queried in Insights.

Incomplete span names in waterfall view

When viewing the span waterfall, span names may be displayed in an incomplete form that is more human-readable than the complete span name. To find the complete name, select that span and look for the Full span name. Knowing the complete name can be valuable for querying that data in Insights.

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