groupbytraceprocessor

README

Group by Trace processor

Status
Stability	beta: traces
Distributions	contrib
Warnings	Statefulness
Issues
Code Owners	@jpkrohling

This processor collects all the spans from the same trace, waiting a pre-determined amount of time before releasing the trace to the next processor. The expectation is that, generally, traces will be complete after the given time.

This processor should be used whenever a processor requires grouped traces to make decisions, such as a tail-based sampler or a per-trace metrics processor. Note that tailsamplingprocessor also implements a similar mechanism and can be used independently.

The batch processor shouldn't be used before this processor, as this one will probably undo part (or much) of the work that the batch processor performs. It's fine to have the batch processor to run right after this one, and every entry in the batch will be a complete trace.

Please refer to config.go for the config spec.

Examples:

processors:
  groupbytrace:
  groupbytrace/2:
    wait_duration: 10s
    num_traces: 1000
    num_workers: 2

Configuration

Refer to config.yaml for detailed examples on using the processor.

The num_traces (default=1,000,000) property tells the processor what's the maximum number of traces to keep in the internal storage. A higher num_traces might incur in a higher memory usage.

The wait_duration (default=1s) property tells the processor for how long it should keep traces in the internal storage. Once a trace is kept for this duration, it's then released to the next consumer and removed from the internal storage. Spans from a trace that has been released will be kept for the entire duration again.

The num_workers (default=1) property controls how many concurrent workers the processor will use to process traces. If you are looking to optimize this value then using GOMAXPROCS could be considered as a starting point.

Metrics

The following metrics are recorded by this processor:

• otelcol_processor_groupbytrace_conf_num_traces represents the maximum number of traces that can be kept by the internal storage. This value comes from the processor's configuration and will never change over the lifecycle of the processor.
• otelcol_processor_groupbytrace_event_latency_bucket, with the following event tag values:
  • onTraceReceived represents the number of traces' parts the processor has received from the previous components
  • onTraceExpired represents the number of traces that finished waiting in memory for spans to arrive
  • onTraceReleased represents the number of traces that have been marked as released to the next component
  • onTraceRemoved represents the number of traces that have been marked for removal from the internal storage
• otelcol_processor_groupbytrace_num_events_in_queue representing the state of the internal queue. Ideally, this number would be close to zero, but might have temporary spikes if the storage is slow.
• otelcol_processor_groupbytrace_num_traces_in_memory representing the state of the internal trace storage, waiting for spans to arrive. It's common to have items in memory all the time if the processor has a continuous flow of data. The longer the wait_duration, the higher the amount of traces in memory should be, given enough traffic.
• otelcol_processor_groupbytrace_spans_released and otelcol_processor_groupbytrace_traces_released represent the number of spans and traces effectively released to the next component.
• otelcol_processor_groupbytrace_traces_evicted represents the number of traces that have been evicted from the internal storage due to capacity problems. Ideally, this should be zero, or very close to zero at all times. If you keep getting items evicted, increase the num_traces.
• otelcol_processor_groupbytrace_incomplete_releases represents the traces that have been marked as expired, but had been previously been removed. This might be the case when a span from a trace has been received in a batch while the trace existed in the in-memory storage, but has since been released/removed before the span could be added to the trace. This should always be very close to 0, and a high value might indicate a software bug.

A healthy system would have the same value for the metric otelcol_processor_groupbytrace_spans_released and for three events under otelcol_processor_groupbytrace_event_latency_bucket: onTraceExpired, onTraceRemoved and onTraceReleased.

The metric otelcol_processor_groupbytrace_event_latency_bucket is a bucket and shows how long each event took to be processed in miliseconds. In most cases, it should take less than 5ms for an event to be processed, but it might be the case where an event could take 10ms. Higher latencies are possible, but it should never really reach the last item, representing 1s. Events taking more than 1s are killed automatically, and if you have multiple items in this bucket, it might indicate a bug in the software.

Most metrics are updated when the events occur, except for the following ones, which are updated periodically:

• otelcol_processor_groupbytrace_num_events_in_queue
• otelcol_processor_groupbytrace_num_traces_in_memory

Warnings

• Statefulness: The groupbytrace processor's works best when all spans for a trace are sent to the same collector instance.

Documentation

Index

• func NewFactory() processor.Factory
• type Config

Functions

func NewFactory

func NewFactory() processor.Factory

NewFactory returns a new factory for the Filter processor.

Types

type Config

type Config struct {

	// NumTraces is the max number of traces to keep in memory waiting for the duration.
	// Default: 1_000_000.
	NumTraces int `mapstructure:"num_traces"`

	// NumWorkers is a number of workers processing event queue.
	// Default: 1.
	NumWorkers int `mapstructure:"num_workers"`

	// WaitDuration tells the processor to wait for the specified duration for the trace to be complete.
	// Default: 1s.
	WaitDuration time.Duration `mapstructure:"wait_duration"`

	// DiscardOrphans instructs the processor to discard traces without the root span.
	// This typically indicates that the trace is incomplete.
	// Default: false.
	// Not yet implemented, and an error will be returned when this option is used.
	DiscardOrphans bool `mapstructure:"discard_orphans"`

	// StoreOnDisk tells the processor to keep only the trace ID in memory, serializing the trace spans to disk.
	// Useful when the duration to wait for traces to complete is high.
	// Default: false.
	// Not yet implemented, and an error will be returned when this option is used.
	StoreOnDisk bool `mapstructure:"store_on_disk"`
}

Config is the configuration for the processor.