42 lines
1.9 KiB
Markdown
42 lines
1.9 KiB
Markdown
# TraceConfig
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Global configuration of the trace service. This allows users to change configs for the default
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sampler, maximum events to be kept, etc.
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## TraceParams
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Represents the set of parameters that users can control
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* Default `Sampler` - used when creating a Span if no specific sampler is given. The default sampler
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is a [Probability](Sampling.md) sampler with the probability set to `1/10000`.
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### Limits
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We define limits on the number of attributes, annotations, message events and links on each span
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in order to prevent unbounded memory increase for long-running spans.
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When limits are exceeded, implementations should by default preserve the most recently added values
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and drop the oldest values. Implementations may make this policy configurable.
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Implementations should track the number of dropped items per span. Some backends provide dedicated
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support for tracking these counts. Others do not, but exporters may choose to represent these in
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exported spans in some way (for example, as a tag).
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Implementations may support tracking the total number of dropped items in stats as outlined.
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| Item | Default Limit | Measure for dropped items |
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| --- | --- | --- |
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| Attributes | 32 | opencensus.io/trace/dropped_attributes |
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| Annotations | 32 | opencensus.io/trace/dropped_annotations |
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| Message Events | 128 | opencensus.io/trace/dropped_message_events |
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| Links | 32 | opencensus.io/trace/dropped_links |
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No views should be registered by default on these measures. Users may register views if they
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are interested in recording these measures.
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Implementations should provide a way to override the globals per-span.
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## API Summary
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* Permanently update the active TraceParams.
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* Temporary update the active TraceParams. This API allows changing of the active params for a
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certain period of time. No more than one active temporary update can exist at any moment.
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* Get current active TraceParams.
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