您可能要开始一个新的跨度并提供该跨度的显式父项。假定范围的父级在一个线程中，而您想在另一个线程中开始一个新的范围。在Brave中，每当您调用nextSpan()时，它都会参照当前范围的跨度创建一个跨度。您可以将范围放入范围中，然后调用nextSpan()，如以下示例所示：

// let's assume that we're in a thread Y and we've received
// the `initialSpan` from thread X. `initialSpan` will be the parent
// of the `newSpan`
Span newSpan = null;
try (Tracer.SpanInScope ws = this.tracer.withSpanInScope(initialSpan)) {
	newSpan = this.tracer.nextSpan().name("calculateCommission");
	// ...
	// You can tag a span
	newSpan.tag("commissionValue", commissionValue);
	// ...
	// You can log an event on a span
	newSpan.annotate("commissionCalculated");
}
finally {
	// Once done remember to finish the span. This will allow collecting
	// the span to send it to Zipkin. The tags and events set on the
	// newSpan will not be present on the parent
	if (newSpan != null) {
		newSpan.finish();
	}
}

创建这样的跨度后，必须完成它。否则，不会报告该错误（例如，报告到Zipkin）。