[bg451]

Seeing that people have already mentioned Dapper, I'd add that there are already a few open source implementations of Dapper available. Appdash[1] is a very lightweight tracer that isn't too fancy, but gets the job done. There's also the much bigger, more popular tracer Zipkin[2], which was built by Twitter.

[1] https://github.com/sourcegraph/appdash

[2] https://github.com/openzipkin/zipkin

[Mister_Snuggles]

It looks like both of these require changes to the application. Dapper appears to have the same issue.

My use case is for understanding a closed source application which has a number of separate pieces. Since I don't have the source code, these don't look like viable options.