gp.schedlink.set(newg)
	})

	// Switch to the new goroutine.
	mcall(func(gp *g) {
		// Get newg.
		newg := gp.schedlink.ptr()
		gp.schedlink = 0

		// Park the calling goroutine.
		trace := traceAcquire()
		if trace.ok() {
			// Trace the event before the transition. It may take a
			// stack trace, but we won't own the stack after the
			// transition anymore.
			trace.GoPark(traceBlockDebugCall, 1)
		}

	// Deduct credit for this span allocation and sweep if necessary.
	spanBytes := uintptr(class_to_allocnpages[c.spanclass.sizeclass()]) * _PageSize
	deductSweepCredit(spanBytes, 0)

	traceDone := false
	trace := traceAcquire()
	if trace.ok() {
		trace.GCSweepStart()
		traceRelease(trace)
	}

	// If we sweep spanBudget spans without finding any free
	// space, just allocate a fresh span. This limits the amount

			// Like the runtime/pprof package, even if that bug didn't exist
			// we would still want to do a goroutine-level sleep in between
			// reads to avoid frequent wakeups.
			trace.cpuSleep.sleep(100_000_000)

			tl := traceAcquire()
			if !tl.ok() {
				// Tracing disabled.
				break
			}
			keepGoing := traceReadCPU(tl.gen)
			traceRelease(tl)
			if !keepGoing {
				break
			}
		}
		done <- struct{}{}
	}()

	w.varint(uint64(pageSize))
	w.varint(uint64(minHeapAlign))
	w.varint(uint64(fixedStack))

	// Finish writing the batch.
	w.flush().end()

	// Start tracing.
	trace := traceAcquire()
	if !trace.ok() {
		throw("traceSnapshotMemory: tracing is not enabled")
	}

	// Write out all the heap spans and heap objects.
	for _, s := range mheap_.allspans {
		if s.state.get() == mSpanDead {

	// but we need to make sure the tracer can only observe the
	// start and end states to maintain a coherent model and avoid
	// emitting an event for every single transition.
	trace := traceAcquire()

	if locked {
		// Detach the goroutine from the thread; we'll attach to the goroutine we're
		// switching to before returning.
		gp.lockedm.set(nil)
	}

	if exit {