//   can free a whole span if none of the objects are marked, but that
//   isn't its goal. This can be driven either synchronously by
//   mcentral.cacheSpan for mcentral spans, or asynchronously by
//   sweepone, which looks at all the mcentral lists.
//
// * The span reclaimer looks for spans that contain no marked objects
//   and frees whole spans. This is a separate algorithm because

	// this block. This number is used to help determine when a block
	// may be safely recycled.
	popped atomic.Uint32

	// spans is the set of spans in this block.
	spans [spanSetBlockEntries]atomicMSpanPointer
}

// push adds span s to buffer b. push is safe to call concurrently
// with other push and pop operations.
func (b *spanSet) push(s *mspan) {
	// Obtain our slot.

		c = pp.mcache
	}
	return c
}

// refill acquires a new span of span class spc for c. This span will
// have at least one free object. The current span in c must be full.
//
// Must run in a non-preemptible context since otherwise the owner of
// c could change.
func (c *mcache) refill(spc spanClass) {
	// Return the current cached span to the central lists.
	s := c.alloc[spc]

	if s.allocCount != s.nelems {

	// 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).

		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

					i = start
					continue Spans
				}
			}

			// Span is either paragraph or heading.
			if end-start == 1 && isHeading(lines[start]) {
				kind = spanHeading
			} else if end-start == 1 && isOldHeading(lines[start], lines, start) {
				kind = spanOldHeading
			} else {
				kind = spanPara
			}
		}

		spans = append(spans, span{start, end, kind})
		i = end
	}

		//   "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

			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)