tracing
termcloudprogramming
Following one request through every service it touches, with each step recorded and linked by a shared identifier.
It exists because breaking an application into services broke the stack trace: no single machine sees the whole request any more, and the slow step could be anywhere. A trace reassembles that, which is why it is the tool that answers where the time went. The cost is instrumentation and propagation - every service must pass the identifier along, and one that does not becomes a gap where the trail stops, which is usually the oldest component and often the one being blamed.
Also known as: distributed tracing, span