Propagating Pyroscope labels to async worker threads in Java

[mouhamadalmounayar]

Hello,
I'm using the Pyroscope Java profiling agent to profile a Java application which does a lot of async tasks. I have a method like this:

public CompletableFuture<?> method() {
    return Pyroscope.LabelsWrapper.run(new LabelsSet(key, value), () -> doStuff());
}

The issue is that doStuff() triggers async operations executed on different worker threads. The labels set via LabelsWrapper.run() don't propagate to these worker threads, so the async work isn't profiled with the correct labels.
Is there a recommended way to handle this without adding significant verbosity to the existing code? I'm hoping to avoid manually wrapping every async call.

[korniltsev-grafanista]

No, there is no good way to handle this at the moment.

[mouhamadalmounayar]

No, there is no good way to handle this at the moment.

In that case is it maybe possible to have a method which allows a worker thread to retrieve the captured labels of its parent thread, this would allow explicit label propagation across async boundaries.

Something like:

public static LabelSet getCurrentLabels(); 

This would allow me to do something like this:

LabelSet capturedLabels = Pyroscope.LabelsWrapper.getCurrentLabels();
thread_executor.execute(() -> {
    try (ScopedContext ctx = new ScopedContext(capturedLabels)) {
        // execute async task
    }
})

Eventually, users could override the execute method in a custom executor for example, so the logic does not have to be repeated for each async call. I think it would be practical, would be happy to open a pr.