// Stacks are not considered part of the heap, but the runtime
	// can reuse a span of heap memory for stack memory, and
	// vice-versa.

	// StackInuse is bytes in stack spans.
	//
	// In-use stack spans have at least one stack in them. These
	// spans can only be used for other stacks of the same size.
	//
	// There is no StackIdle because unused stack spans are
	// returned to the heap (and hence counted toward HeapIdle).

)

// TestClientTracing exercises the trace generation features of Istio, based on the Envoy Trace driver for zipkin using
// client initiated tracing using envoy traceheader.
// The test verifies that all expected spans (a client span and a server span for each service call in the sample bookinfo app)
// are generated and that they are all a part of the same distributed trace with correct hierarchy and name.
func TestClientTracing(t *testing.T) {

// The heap is swept span-by-span both lazily (when a goroutine needs another span)
// and concurrently in a background goroutine (this helps programs that are not CPU bound).
// At the end of STW mark termination all spans are marked as "needs sweeping".
//
// The background sweeper goroutine simply sweeps spans one-by-one.
//
// To avoid requesting more OS memory while there are unswept spans, when a

		return false
	}
	systemstack(func() {
		gp := getg().m.curg
		for i := 0; i < batchSize && !(preemptible && gp.preempt); i++ {
			span := work.wbufSpans.free.first
			if span == nil {
				break
			}
			work.wbufSpans.free.remove(span)
			mheap_.freeManual(span, spanAllocWorkBuf)
		}
	})
	more := !work.wbufSpans.free.isEmpty()
	unlock(&work.wbufSpans.lock)
	return more

# A note on distributed tracing:
#
# Although Istio proxies are able to automatically send spans, they need some
# hints to tie together the entire trace. Applications need to propagate the
# appropriate HTTP headers so that when the proxies send span information, the
# spans can be correlated correctly into a single trace.
#
# To do this, an application needs to collect and propagate headers from the

            @Override
            public String toString() {
                return pattern.toString();
            }
        };
    }

    /**
     * Get the number of lines that the expected message spans.
     *
     * @return the number of lines in this message
     */
    public int getNumLines() {
        return numLines;
    }

    /**

		//   "The text in style, script, title, and textarea elements
		//   must not have an escaping text span start that is not
		//   followed by an escaping text span end."
		// Furthermore, spoofing an escaping text span end could lead
		// to different interpretation of a </script> sequence otherwise
		// masked by the escaping text span, and spoofing a start could

		}

		// Check if val points to a heap span.
		span := spanOfHeap(val)
		if span == nil {
			continue
		}

		// Check if val points to an allocated object.
		idx := span.objIndex(val)
		if span.isFree(idx) {
			continue
		}

		// val points to an allocated object. Mark it.
		obj := span.base() + idx*span.elemsize
		greyobject(obj, b, i, span, gcw, idx)
	}
}

			if start < 0 {
				start = end
			}
		}
	}

	// Last field might end at EOF.
	if start >= 0 {
		spans = append(spans, span{start, len(s)})
	}

	// Create strings from recorded field indices.
	a := make([]string, len(spans))
	for i, span := range spans {
		a[i] = s[span.start:span.end]
	}

	return a
}

	}

	copystack(gp, newsize)
}

// freeStackSpans frees unused stack spans at the end of GC.
func freeStackSpans() {
	// Scan stack pools for empty stack spans.
	for order := range stackpool {
		lock(&stackpool[order].item.mu)
		list := &stackpool[order].item.span
		for s := list.first; s != nil; {
			next := s.next
			if s.allocCount == 0 {
				list.remove(s)