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)
}

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

	}
	// 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))

	}
	// 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))

		err = mg.bucketLoader(GlobalContext, metricValues, mg.cache, mg.buckets)
	} else {
		err = mg.loader(GlobalContext, metricValues, mg.cache)
	}

	// There is no way to handle errors here, so we panic the current goroutine
	// and the Metrics API handler returns a 500 HTTP status code. This should
	// normally not happen, and usually indicates a bug.
	logger.CriticalIf(GlobalContext, errors.Wrap(err, "failed to get metrics"))

		}
	}()
	C.callPanic()
}

// Test that C code can return a value if it calls a Go function that
// causes a stack copy.
func testReturnAfterGrow(t *testing.T) {
	// Use a new goroutine so that we get a small stack.
	c := make(chan int)
	go func() {
		c <- int(C.returnAfterGrow())
	}()
	if got, want := <-c, 123456; got != want {
		t.Errorf("got %d want %d", got, want)
	}
}