'x-datadog-parent-id',
        'x-datadog-sampling-priority',

        # W3C Trace Context. Compatible with OpenCensusAgent and Stackdriver Istio
        # configurations.
        'traceparent',
        'tracestate',

        # Cloud trace context. Compatible with OpenCensusAgent and Stackdriver Istio
        # configurations.
        'x-cloud-trace-context',

	// pcBuf[1:] after inline expansion.
	logicalStackSentinel = ^uintptr(0)
)

// traceStack captures a stack trace from a goroutine and registers it in the trace
// stack table. It then returns its unique ID. If gp == nil, then traceStack will
// attempt to use the current execution context.
//
// skip controls the number of leaf frames to omit in order to hide tracer internals

	_ "unsafe" // for go:linkname
)

// gTraceState is per-G state for the tracer.
type gTraceState struct {
	traceSchedResourceState
}

// reset resets the gTraceState for a new goroutine.
func (s *gTraceState) reset() {
	s.seq = [2]uint64{}
	// N.B. s.statusTraced is managed and cleared separately.
}

// mTraceState is per-M state for the tracer.
type mTraceState struct {

	// current in-progress goroutine profile
	goroutineProfiled goroutineProfileStateHolder

	coroarg *coro // argument during coroutine transfers

	// Per-G tracer state.
	trace gTraceState

	// Per-G GC state

	// gcAssistBytes is this G's GC assist credit in terms of
	// bytes allocated. If this is positive, then the G has credit
	// to allocate gcAssistBytes bytes without assisting. If this

				if s.g.m != nil {
					ug.mid = int64(s.g.m.procid)
				}
				ug.status = readgstatus(s.g) &^ _Gscan
				ug.waitreason = s.g.waitreason
				ug.inMarkAssist = s.g.inMarkAssist
				ug.stackID = traceStack(0, gp, gen)
			}
			resumeG(s)
			casgstatus(me, _Gwaiting, _Grunning)
		})
		if ug.goid != 0 {
			untracedGs = append(untracedGs, ug)
		}
	})

	if !stopTrace {