OpenTelemetry integration

[jack-pappas]

@omarabid mentioned in #1077 a new implementation of tagging that'll work across multiple threads. Has there been any consideration towards having that work with OpenTelemetry-instrumented code? A good number of libraries are now instrumented with OpenTelemetry, and it'd be useful to be able to cross-reference collected OpenTelemetry data against Pyroscope; I think that would achieve the same goal as the new cross-thread tagging support.

If Pyroscope doesn't have a way to reference the OpenTelemetry data directly (e.g. by having the UI reach out to fetch tracing span data and/or metrics from some storage backend), it should still be possible to make this work by implementing an OpenTelemetry sink which writes the span data to Pyroscope. That'd let users of OpenTelemetry-instrumented libraries just configure their app to use the Pyroscope sink, without needing to add any separate Pyroscope-specific instrumentation.

[Rperry2174]

Great point @jack-pappas ! We actually have an integration like this for Go already with our otelpyroscope package! I think that it will be slightly more complicated to add this for Java, but definitely within reason...

We also have a proof-of-concept in our examples folder of linking Pyroscope to Jaeger (with a custom Jaeger UI).

Im curious, what tracing tool are you using that you'd like to link with profiles?