Understand and use the distributed tracing UI

Distributed tracing helps you monitor and analyze the behavior of your distributed system. After you enable distributed tracing, you can use our UI tools to search for traces and analyze them.

For example, let's say you are an engineer troubleshooting errors in a complex transaction spanning many services. Here's what you can do in our UI:

1. Open the distributed tracing UI page.
2. Sort through your traces using a filter to find that specific request and show only traces containing errors.
3. On the trace details page, you review the span along the request route that originated the error.
4. Noting the error class and message, navigate to the service from its span in the trace so you can see that the error is occurring at a high rate.

Read on to explore the options in the distributed tracing UI.

Open the distributed tracing UI

Here's how you can access the distributed tracing UI, depending on the type of search you want to do:

Find traces that are useful

We have a variety of tools to help you find traces and spans so you can resolve issues. The opening distributed tracing page is populated with a default list of traces, and you can quickly refine this list using these tools:

• Query bar filters
• Left-pane filters
• Trace groups
• Scatter plot chart
• Interactive charts

Filter using the query bar

The Find traces query bar is a quick way to narrow your search for traces. You can either start typing in the query bar or use the dropdown to create a compound query.

Query returns are based on span attributes, not on trace attributes. You define spans that have certain criteria, and the search displays traces that contain those spans.

If you use a multi-attribute filter, it is affected by first attribute selected. Distributed tracing reports on two types of data: transaction events and spans. When you select an attribute in the filter, the data type that attribute is attached to dictates the available attributes. For example, if you filter on an attribute that is attached to a transaction event, only transaction event attributes are available when you attempt to add filter on additional attribute values.

Queries for traces are similar to NRQL (our query language). Here are the main exceptions:

• String values don't require quote marks (for example, you can use either appName = MyApp or appName = 'MyApp')
• The like operator doesn’t require % (for example, you can use either appName like product or appName like %product%).

Here are two query bar examples:

Left-pane filters

Besides the query bar at the top of the page, you can use a variety of filters in the left pane to find traces you're interested in.

• Infinite tracing data: Select this only to show traces related to the Infinite Tracing feature.

• Multi span traces only: Use this to hide single-span traces.

• Error filters: Under Errors select the errors to filter by.

• Histogram filters: Below Errors at the bottom of the left pane, you can click More filters to show histogram filters. Drag the sliders to change the values, such as Trace duration:

  • Drag the left end of the slider for greater-than comparisons.
  • Drag the right end of the slider for less-than comparisons.
  • Drag each end of the slider toward the center to filter by a range.
  

Trace groups

The default view of distributed tracing shows traces grouped by the same root entry span. In other words, traces are grouped by the span where New Relic began recording the request. You can slide the toggle Group similar traces to turn this on and off.

With trace groups you get a high-level view of traces so you can understand request behavior for groups of similar traces. This helps you understand dips or spikes in trace count, duration, and errors. When you click on one of the trace groups, you get all the standard details in context of the specific trace group you selected.

You can control what you see in the trace groups list by using left-pane filters.

Filter using the scatter plot

The trace scatter plot is a quick way to search for outlying traces. This is available on the opening page of distributed tracing if you turn off the Group similar traces toggle at the top of the page.

In the scatter plot, you can move the cursor across the chart to view trace details and you can click individual points to get details:

Here's how you can control what's displayed in the scatter plot:

1. In the View by dropdown, select the duration type:
   • Backend duration
   • Root span duration
   • Trace duration
2. In Facet traces by, select one of these options:
   • Root entry span: Group by the root transaction, which is 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/%".
   • Root entity: Group by the name of the first entity in traces. In a trace where Service A calls Service B and Service B calls Service C, the root entity would be Service A.
   • Errors: Group by whether or not traces contain errors.
3. For tips about how to change the filters on the scatter plot, see Left-pane filters.

Trace charts

When you open distributed tracing, you'll see three charts at the top (if Group similar traces is turned on). These charts show you the trace-count, 95th percentile duration, and error-count for each of the trace groups listed in the table below the charts.

To change the filters on these charts, see Left-pane filters.

Trace details UI page

When you select a trace from the trace list, you see an entity map at the top followed by a waterfall view displaying that trace's spans.

Entity map

If a trace involves more than one entity, and we have information about those entities, the trace page includes a map.

Waterfall view

The waterfall view in the bottom section of the page displays a detailed flow of all the operations that make up the distributed trace. This allows you to see the exact context from which latency and errors arise.

Waterfall controls

The waterfall view has a number of controls to make it easier to find spans that you care about:

• Expand all/Collapse all: Use this option to toggle between showing every span (including in-process spans) and showing collapsed spans.
• Standard/Manual: In standard mode, you get a semi-expanded view that includes the first span in each process. In manual mode, you only see what you expand.
  • Both Standard and Manual are overridden by Expand all, which displays all spans.
  • If you're in standard or manual mode, and you click Collapse all, the waterfall is reset to the default for the mode you're using.
• Focus on: If your span has errors or anomalies, you'll see checkboxes for each of these types. If you check these boxes, your waterfall view will collapse all other types of spans and only show color-coded error or anomalous spans. This is a quick way to find problematic spans.
• Maximize: This allows you to see more spans on the screen by expanding the waterfall and hiding the entity map.

Waterfall span properties

The UI indicates span properties with these icons:

Span property	Indicator	Description
Service		This icon represents a span that's a service's entry point.
In-process		This icon represents an in-process span, which is a span that takes place within a process (as opposed to a cross-process span). Examples: middleware instrumentation, user-created spans.
Datastore		This icon represents a span call to a datastore.
External		This icon represents category representing a call to an external service made via HTTP.
Browser app		This icon represents a browser application span.
Lambda		This icon represents a span from a Lambda function.

Some spans will have additional indicators:

Span property	Indicator	Description
Type of connection		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. For more on relationships between spans, see Trace structure.
Errors		A span with an error. See How to understand span errors.
Anomalous		This icon represents the detection of an anomalous span.
Orphaned spans		Some spans may be "orphaned," or separated, from the trace. These spans will appear at the bottom of the trace. For more details, see Fragmented traces.
Multiple app names		When beside a span name, this represents an entity that has had multiple app names set. Select this to see all app names it reports to. To search trace data by alternate app names, use the appName attribute.
Client/server time difference		If a span's duration indicator is not completely colored in (like in this example), it means that there is a time discrepancy between the server-side duration and the client-side duration for that activity. For details on this, see Client/server time difference.

For more on the trace structure and how span properties are determined, see Trace structure.

Span details pane

When you select a span, a pane opens up with span details. These details can be helpful for troubleshooting performance issues. This page has three tabs:

• Performance: You’ll see charts showing the average duration and throughput for that span operation, as well as how the performance of this specific span compares to the average.
• Attributes: You can learn more about attributes from our data dictionary.
• Details: You can view details, such as the span's full name and data source.

What a span displays is based on its span type. For example, the datastore span's details will include the database query.

View related logs

If you are using our logs in context feature, you can see any logs that are linked to your traces:

1. Go to the trace details page by clicking on a trace.
2. In the upper-left corner of the span details page, click the Logs tab.
3. For details related to an individual log message, click directly on the message.

Additional UI details

Here are some additional distributed tracing UI details, rules, and limits:

How to understand span errors

Span-level errors show you where errors originated in a process, how they bubbled up, and where they were handled. Every span that ends with an error is shown with an error in the UI and contributes to the total error count for that trace.

Here are some general tips about understanding span errors:

• Spans with errors are highlighted red in the distributed tracing UI. You can see more information on the Error Details pane for each span.

• All spans that exit with errors are counted in the span error count.

• When multiple errors occur on the same span, only one is written to the span in this order of precedence:

  • A noticeError
  • The most recent span error within the scope of that span

  This table describes how different span errors are handled:

  Error type	Description
  Spans ending in errors	An error that leaves the boundary of a span results in an error on that span and on any ancestor spans that also exit with an error, until the error is caught or exits the transaction. You can see if an error is caught in an ancestor span.
  Notice errors	Errors noticed by calls to the agent noticeError API or by the automatic agent instrumentation are attached to the currently executing span.
  Response code errors	Response code errors are attached to the associated span, such as: Client span: External transactions prefixed with http or db. Entry span: In the case of a transaction ending in a response code error. The response code for these spans is captured as an attribute http.statusCode and attached to that span.
  OpenTelemetry Errors	The Error Details box of the right pane is populated by spans containing otel.status_code = ERROR and displays the content of otel.status_description. Tip OpenTelemetry span events handled by the app/service are displayed independently of span error status and are not necessarily associated with a span error status. You can view span event exceptions and non-exceptions by clicking View span events in the right pane.

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.

Client span 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:

  

  A. 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. B. 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. C. When a client span starts after a server span, this is most likely clock skew.

Fragmented traces

Fragmented traces are traces with missing spans. When a span is missing or has invalid parent span IDs, its children spans become separated from the rest of the trace, which we refer to as "orphaned." Orphaned spans appear at the bottom of the trace, and they will lack connecting lines to the rest of the trace. If you have fragmented spans, you'll see the word Fragmented at the top of the details page:

Types of orphaned span properties indicated in the UI:

• No root span. Missing the root span, which is the first operation in the request. When this happens, the span with the earliest timestamp is displayed as the root.

• Orphaned span. A single span with a missing parent span. This could be due to the parent span having an ID that doesn't match its child span.

• Orphaned trace fragment. A group of connected spans where the first span in the group is an orphan span.

This can happen for a number of reasons, including:

• Collection limits. Some high-throughput applications may exceed collection limits (for example, APM agent collection limits, or API limits). When this happens, it may result in traces having missing spans. One way to remedy this is to turn off some reporting, so that the limit is not reached.

• Incorrect instrumentation. If an application is instrumented incorrectly, it won't pass trace context correctly and this will result in fragmented traces. To remedy this, examine the data source that is generating orphan spans to ensure instrumentation is done correctly. To discover a span's data source, select it and examine its span details.

• Spans still arriving. If some parent spans haven't been collected yet, this can result in temporary gaps until the entire trace has reported.

• UI display limits. Orphaned spans may result if a trace exceeds the 10K span display limit.

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

  For more information on the factors affecting your access to accounts, see Account access.

Span limits and sampling

See Language agents: adaptive sampling.

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 with NRQL.

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 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.

• The UI may have hit its 10K span display limit.

  All spans collected, including those not displayed, can be queried with NRQL.