Flamegraph
A stacked visualisation that shows where time is spent across a call tree in a trace or profile.
Definition
A flamegraph is a visualisation technique that represents a call stack as a series of horizontally stacked bars. Each bar represents a function or span, its width shows the relative time spent in that call, and the vertical stacking shows the call hierarchy. Flamegraphs make it easy to spot the widest bars — the calls consuming the most time.
In depth
Originally developed for CPU profiling by Brendan Gregg, flamegraphs have been widely adopted for distributed trace visualisation. In the tracing context, each span becomes a bar whose width is proportional to its duration, and child spans are nested beneath their parent. Unlike traditional waterfall views, flamegraphs make it immediately obvious where latency is concentrated even in deeply nested call trees with hundreds of spans. obseria.io renders flamegraphs for every trace with P50/P95/P99 latency overlays, making it easy to distinguish outliers from the typical call path.
Related terms
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