t.Error(fn, err)
			continue
		}
		defer sf.Close()
		sb := bufio.NewScanner(sf)

		// Compare the two, in SNG format, line by line.
		for {
			pdone := !pb.Scan()
			sdone := !sb.Scan()
			if pdone && sdone {
				break
			}
			if pdone || sdone {
				t.Errorf("%s: Different sizes", fn)
				break
			}
			ps := pb.Text()
			ss := sb.Text()

	// The close of the Done channel may happen asynchronously,
	// after the cancel function returns.
	//
	// WithCancel arranges for Done to be closed when cancel is called;
	// WithDeadline arranges for Done to be closed when the deadline
	// expires; WithTimeout arranges for Done to be closed when the timeout
	// elapses.
	//
	// Done is provided for use in select statements:
	//

            assert result.groupedOutput.task(':2:log').output == "Error from 2\nOutput from 2\nDone with 2\nDone with 2"
            assert result.groupedOutput.task(':3:log').output == "Error from 3\nOutput from 3\nDone with 3\nDone with 3"
        } else {
            assert result.groupedOutput.task(':1:log').output == "Output from 1\nDone with 1"

	probablyStillBlocked = 10 * time.Second
)

func mustBlock(t *testing.T, desc string, f func()) (wait func(*testing.T)) {
	t.Helper()

	done := make(chan struct{})
	go func() {
		f()
		close(done)
	}()

	timer := time.NewTimer(quiescent)
	defer timer.Stop()
	select {
	case <-done:
		t.Fatalf("%s unexpectedly did not block", desc)
	case <-timer.C:
	}

	return func(t *testing.T) {

	}
	go writer(&rwm, num_iterations, &activity, cdone)
	for ; i < numReaders; i++ {
		go reader(&rwm, num_iterations, &activity, cdone)
	}
	// Wait for the 2 writers and all readers to finish.
	for i := 0; i < 2+numReaders; i++ {
		<-cdone
	}
}

func TestRWMutex(t *testing.T) {
	defer GOMAXPROCS(GOMAXPROCS(-1))
	n := 1000
	if testing.Short() {
		n = 5
	}
	HammerRWMutex(1, 1, n)

			mu.Unlock()
			select {
			case <-stop:
				return
			default:
			}
		}
	}()
	done := make(chan bool, 1)
	go func() {
		for i := 0; i < 10; i++ {
			time.Sleep(100 * time.Microsecond)
			mu.Lock()
			mu.Unlock()
		}
		done <- true
	}()
	select {
	case <-done:
	case <-time.After(10 * time.Second):
		t.Fatalf("can't acquire Mutex in 10 seconds")
	}
}

Deleting the cache when it is no longer needed can be done.  However this may delete the purpose of the cache
which is designed to persist between app restarts.

```kotlin
cache.delete()
```
 
## Pruning the Cache

Pruning the entire Cache to clear space temporarily can be done using evictAll.

```kotlin
cache.evictAll()
```

Removing individual items can be done using the urls iterator.

func LoadUint32(addr *uint32) (val uint32)

// LoadUint64 atomically loads *addr.
// Consider using the more ergonomic and less error-prone [Uint64.Load] instead
// (particularly if you target 32-bit platforms; see the bugs section).
func LoadUint64(addr *uint64) (val uint64)

// LoadUintptr atomically loads *addr.
// Consider using the more ergonomic and less error-prone [Uintptr.Load] instead.

		t.Fatal("Unlock timed out, which should not happen")
	case <-timer.C:
	}
}

// Borrowed from mutex_test.go
func HammerMutex(m *DRWMutex, loops int, cdone chan bool) {
	for i := 0; i < loops; i++ {
		m.Lock(id, source)
		m.Unlock(context.Background())
	}
	cdone <- true
}

// Borrowed from mutex_test.go
func TestMutex(t *testing.T) {
	loops := 200
	if testing.Short() {
		loops = 5
	}

	// STW.
	traceEvSTWBegin // STW start [timestamp, kind]
	traceEvSTWEnd   // STW done [timestamp]

	// GC events.
	traceEvGCActive           // GC active [timestamp, seq]
	traceEvGCBegin            // GC start [timestamp, seq, stack ID]
	traceEvGCEnd              // GC done [timestamp, seq]
	traceEvGCSweepActive      // GC sweep active [timestamp, P ID]