}
	// Wait for all parallel RLock()s to succeed.
	for i := 0; i < numReaders; i++ {
		<-clocked
	}
	for i := 0; i < numReaders; i++ {
		cunlock <- true
	}
	// Wait for the goroutines to finish.
	for i := 0; i < numReaders; i++ {
		<-cdone
	}
}

// Borrowed from rwmutex_test.go
func TestParallelReaders(t *testing.T) {
	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1))

// panicking goroutine. Executing a call to recover inside a deferred
// function (but not any function called by it) stops the panicking sequence
// by restoring normal execution and retrieves the error value passed to the
// call of panic. If recover is called outside the deferred function it will
// not stop a panicking sequence. In this case, or when the goroutine is not
// panicking, recover returns nil.
//

	ctx, cancel := context.WithCancel(context.Background())
	go func() {
		select {
		case <-ctx1.Done():
		case <-ctx2.Done():
		// The lock acquirer decides to cancel, exit this goroutine
		case <-ctx.Done():
		}

		cancel()
	}()
	return ctx, cancel
}

func (ld sharedLock) GetLock(ctx context.Context) (context.Context, context.CancelFunc) {
	l := <-ld.lockContext

// TestPreparedStmtConcurrentClose test calling close and executing SQL concurrently
// for example: one goroutine found error and just close the database, and others are executing SQL
// this test making sure that the gorm would not get a Segmentation Fault,
// and the only error cause by this is using a closed Stmt or gorm.ErrInvalidDB
// and all of the goroutine must got gorm.ErrInvalidDB after database close
func TestPreparedStmtConcurrentClose(t *testing.T) {

// it is no longer referenced, so it must be kept alive (see runtime.KeepAlive)
// until any memory allocated from it is no longer needed.
//
// An Arena must never be used concurrently by multiple goroutines.
type Arena struct {
	a unsafe.Pointer
}

// NewArena allocates a new arena.
func NewArena() *Arena {
	return &Arena{a: runtime_arena_newArena()}
}

const jsonSplitSize = 128 << 10

// startReaders will read the header if needed and spin up a parser
// and a number of workers based on GOMAXPROCS.
// If an error is returned no goroutines have been started and r.err will have been set.
func (r *PReader) startReaders() {
	r.bufferPool.New = func() interface{} {
		return make([]byte, jsonSplitSize+1024)
	}

	// Create queue

type NotificationPeerErr struct {
	Host xnet.Host // Remote host on which the rpc call was initiated
	Err  error     // Error returned by the remote peer for an rpc call
}

// A NotificationGroup is a collection of goroutines working on subtasks that are part of
// the same overall task.
//
// A zero NotificationGroup is valid and does not cancel on error.
type NotificationGroup struct {
	workers    *workers.Workers

	closedMu sync.Mutex
	closer   io.ReadCloser
	closed   bool
}

func (pr *progressReader) Read(p []byte) (n int, err error) {
	// This ensures that Close will block until Read has completed.
	// This allows another goroutine to close the reader.
	pr.closedMu.Lock()
	defer pr.closedMu.Unlock()
	if pr.closed {
		return 0, errors.New("progressReader: read after Close")
	}
	return pr.processedReader.Read(p)
}

	neededFrags = make(map[urlFrag][]string) // URL#frag -> who needs it
)

var aRx = regexp.MustCompile(`<a href=['"]?(/[^\s'">]+)`)

// Owned by crawlLoop goroutine:
var (
	linkSources = make(map[string][]string) // url no fragment -> sources
	fragExists  = make(map[urlFrag]bool)
	problems    []string
)

func localLinks(body string) (links []string) {

		// lk2
		lk2ch := make(chan struct{})
		go func() {
			defer close(lk2ch)
			nsLk.lock(ctx, "volume", "path", "source", "opsID", false, 1*time.Millisecond)
		}()
		time.Sleep(1 * time.Millisecond) // wait for goroutine to advance; ref=2

		// Unlock the 1st lock; ref=1 after this line
		nsLk.unlock("volume", "path", false)

		// Taking another lockMapMutex here allows queuing up additional lockers. This should